Garry Gold

All Publications

• Automated Classification of Radiographic Knee Osteoarthritis Severity Using Deep Neural Networks. Radiology. Artificial intelligence Thomas, K. A., Kidzinski, L., Halilaj, E., Fleming, S. L., Venkataraman, G. R., Oei, E. H., Gold, G. E., Delp, S. L. 2020; 2 (2): e190065

  Abstract

  Purpose: To develop an automated model for staging knee osteoarthritis severity from radiographs and to compare its performance to that of musculoskeletal radiologists.Materials and Methods: Radiographs from the Osteoarthritis Initiative staged by a radiologist committee using the Kellgren-Lawrence (KL) system were used. Before using the images as input to a convolutional neural network model, they were standardized and augmented automatically. The model was trained with 32116 images, tuned with 4074 images, evaluated with a 4090-image test set, and compared to two individual radiologists using a 50-image test subset. Saliency maps were generated to reveal features used by the model to determine KL grades.Results: With committee scores used as ground truth, the model had an average F1 score of 0.70 and an accuracy of 0.71 for the full test set. For the 50-image subset, the best individual radiologist had an average F1 score of 0.60 and an accuracy of 0.60; the model had an average F1 score of 0.64 and an accuracy of 0.66. Cohen weighted kappa between the committee and model was 0.86, comparable to intraexpert repeatability. Saliency maps identified sites of osteophyte formation as influential to predictions.Conclusion: An end-to-end interpretable model that takes full radiographs as input and predicts KL scores with state-of-the-art accuracy, performs as well as musculoskeletal radiologists, and does not require manual image preprocessing was developed. Saliency maps suggest the model's predictions were based on clinically relevant information. Supplemental material is available for this article. © RSNA, 2020.

  View details for DOI 10.1148/ryai.2020190065

  View details for PubMedID 32280948

• pyKNEEr: An image analysis workflow for open and reproducible research on femoral knee cartilage. PloS one Bonaretti, S., Gold, G. E., Beaupre, G. S. 2020; 15 (1): e0226501

  Abstract

  Transparent research in musculoskeletal imaging is fundamental to reliably investigate diseases such as knee osteoarthritis (OA), a chronic disease impairing femoral knee cartilage. To study cartilage degeneration, researchers have developed algorithms to segment femoral knee cartilage from magnetic resonance (MR) images and to measure cartilage morphology and relaxometry. The majority of these algorithms are not publicly available or require advanced programming skills to be compiled and run. However, to accelerate discoveries and findings, it is crucial to have open and reproducible workflows. We present pyKNEEr, a framework for open and reproducible research on femoral knee cartilage from MR images. pyKNEEr is written in python, uses Jupyter notebook as a user interface, and is available on GitHub with a GNU GPLv3 license. It is composed of three modules: 1) image preprocessing to standardize spatial and intensity characteristics; 2) femoral knee cartilage segmentation for intersubject, multimodal, and longitudinal acquisitions; and 3) analysis of cartilage morphology and relaxometry. Each module contains one or more Jupyter notebooks with narrative, code, visualizations, and dependencies to reproduce computational environments. pyKNEEr facilitates transparent image-based research of femoral knee cartilage because of its ease of installation and use, and its versatility for publication and sharing among researchers. Finally, due to its modular structure, pyKNEEr favors code extension and algorithm comparison. We tested our reproducible workflows with experiments that also constitute an example of transparent research with pyKNEEr, and we compared pyKNEEr performances to existing algorithms in literature review visualizations. We provide links to executed notebooks and executable environments for immediate reproducibility of our findings.

  View details for DOI 10.1371/journal.pone.0226501

  View details for PubMedID 31978052

• Non-ionic CT Contrast Solutions Rapidly Alter Bovine Cartilage and Meniscus Mechanics. Osteoarthritis and cartilage Baylon, E. G., Crowder, H. A., Gold, G. E., Levenston, M. E. 2020

  Abstract

  To evaluate effects of a common CT contrast agent (iohexol) on the mechanical behaviors of cartilage and meniscus.Indentation responses of juvenile bovine cartilage and meniscus were monitored following exposure to undiluted contrast agent (100% CA), 50% CA/water, 50% CA/Phosphate Buffered Saline (PBS) or PBS alone, and during re-equilibration in PBS. The normalized peak force (Fpk¯), effective osmotic strain (εosm), and normalized effective contact modulus (Ec¯) were calculated for every cycle, with time constants determined for both exposure and recovery via mono- or biexponential fits to Fpk¯.All cartilage CA groups exhibited long-term increases in Fpk¯ following exposure, although the hyperosmolal 100% CA and 50% CA/PBS groups showed an initial transient decrease. Meniscus presented opposing trends, with decreasing Fpk¯ for all CA groups. Re-equilibration in PBS for 1hr after exposure to 100% CA produced recovery to baseline Fpk¯ in cartilage but not in meniscus, and extended tests indicated that meniscus required ∼2.5 hours to recover halfway. Ec¯ increased with CA exposure time for cartilage but decreased for meniscus, suggesting an increased effective stiffness for cartilage and decreased stiffness for meniscus. Long-term changes to εosm in both tissues were consistent with changes in Ec¯.Exposure to iohexol solutions affected joint tissues differentially, with increased cartilage stiffness, likely relating to competing hyperosmotic and hypotonic interactions with tissue fixed charges, and decreased meniscus stiffness, likely dominated by hyperosmolarity. These altered tissue mechanics could allow non-physiological deformation during ambulatory weight-bearing, resulting in an increased risk of tissue or cell damage.

  View details for DOI 10.1016/j.joca.2020.05.013

  View details for PubMedID 32535082

• Rapid volumetric gagCEST imaging of knee articular cartilage at 3 T: evaluation of improved dynamic range and an osteoarthritic population. NMR in biomedicine Watkins, L. E., Rubin, E. B., Mazzoli, V., Uhlrich, S. D., Desai, A. D., Black, M., Ho, G. K., Delp, S. L., Levenston, M. E., Beaupré, G. S., Gold, G. E., Kogan, F. 2020: e4310

  Abstract

  Chemical exchange saturation transfer of glycosaminoglycans, gagCEST, is a quantitative MR technique that has potential for assessing cartilage proteoglycan content at field strengths of 7 T and higher. However, its utility at 3 T remains unclear. The objective of this work was to implement a rapid volumetric gagCEST sequence with higher gagCEST asymmetry at 3 T to evaluate its sensitivity to osteoarthritic changes in knee articular cartilage and in comparison with T2 and T1ρ measures. We hypothesize that gagCEST asymmetry at 3 T decreases with increasing severity of osteoarthritis (OA). Forty-two human volunteers, including 10 healthy subjects and 32 subjects with medial OA, were included in the study. Knee Injury and Osteoarthritis Outcome Scores (KOOS) were assessed for all subjects, and Kellgren-Lawrence grading was performed for OA volunteers. Healthy subjects were scanned consecutively at 3 T to assess the repeatability of the volumetric gagCEST sequence at 3 T. For healthy and OA subjects, gagCEST asymmetry and T2 and T1ρ relaxation times were calculated for the femoral articular cartilage to assess sensitivity to OA severity. Volumetric gagCEST imaging had higher gagCEST asymmetry than single-slice acquisitions (p = 0.015). The average scan-rescan coefficient of variation was 6.8%. There were no significant differences in average gagCEST asymmetry between younger and older healthy controls (p = 0.655) or between healthy controls and OA subjects (p = 0.310). T2 and T1ρ relaxation times were elevated in OA subjects (p < 0.001 for both) compared with healthy controls and both were moderately correlated with total KOOS scores (rho = -0.181 and rho = -0.332 respectively). The gagCEST technique developed here, with volumetric scan times under 10 min and high gagCEST asymmetry at 3 T, did not vary significantly between healthy subjects and those with mild-moderate OA. This further supports a limited utility for gagCEST imaging at 3 T for assessment of early changes in cartilage composition in OA.

  View details for DOI 10.1002/nbm.4310

  View details for PubMedID 32445515

• Diagnostic Accuracy of Quantitative Multi-Contrast 5-Minute Knee MRI Using Prospective Artificial Intelligence Image Quality Enhancement. AJR. American journal of roentgenology Chaudhari, A. S., Grissom, M. J., Fang, Z., Sveinsson, B., Lee, J. H., Gold, G. E., Hargreaves, B. A., Stevens, K. J. 2020

  Abstract

  Potential approaches for abbreviated knee MRI, including prospective acceleration with deep learning, have achieved limited clinical implementation to date.The objective of this study was to evaluate the inter-reader agreement of conventional knee MRI and a 5-minute 3D quantitative double-echo steady-state (qDESS) sequence with automatic T2 mapping and deep-learning super-resolution (DLSR) augmentation, as well as to compare the diagnostic performance of the two methods with respect to findings from arthroscopic surgery.A total of 51 patients with knee pain underwent knee MRI that included an additional 3D qDESS sequence with automatic T2 mapping. Fourier interpolation was followed by prospective DLSR to enhance qDESS slice-resolution twofold. A musculoskeletal radiologist and a radiology resident performed retrospective independent evaluations of the articular cartilage, menisci, ligaments, bones, extensor mechanism, and synovium using conventional MRI. Following a two-month washout period, the readers reviewed qDESS images alone, followed by qDESS with the automatic T2 maps. Inter-reader agreement between conventional MRI and qDESS was computed using percent agreement and Cohen's Kappa. The sensitivity and specificity of conventional MRI, qDESS alone, and qDESS+T2 were compared with arthroscopic findings using exact McNemar's tests.Conventional MRI and qDESS demonstrated 92% agreement in evaluation of articular cartilage, menisci, ligaments, bones, extensor mechanism, and synovium combined. Kappa was 0.79 (0.76-0.81) across all imaging findings. In the 43/51 patients who underwent arthroscopy, sensitivity and specificity were not significantly different (p=0.23-1.00) between conventional MRI (sensitivity: 58%-93%; specificity: 27%-87%) and qDESS alone (sensitivity: 54%-90%; specificity: 23%-91%) for cartilage, menisci, ligaments, and synovium. Sensitivity and specificity for grade 1 cartilage lesions were 33%/56% for conventional MRI, 23%/53% for qDESS (p=0.81), and 46%/39% for qDESS+T2 (p=0.80); for grade 2A lesions, 27%/53% for conventional MRI, 26%/52% for qDESS (p=0.02), and 58%/40% for qDESS+T2 (p<0.001).qDESS prospectively enhanced with deep learning had strong inter-reader agreement with conventional knee MRI and near-equivalent diagnostic performance with respect to arthroscopy. The ability of qDESS to automatically generate T2 maps increases sensitivity for cartilage abnormalities. Clinical Impact: qDESS using prospective artificial intelligence image quality enhancement may facilitate an abbreviated knee MRI protocol while generating quantitative T2 maps.

  View details for DOI 10.2214/AJR.20.24172

  View details for PubMedID 32755384

• Multiparametric MRI Characterization of Knee Articular Cartilage and Subchondral Bone Shape in Collegiate Basketball Players. Journal of orthopaedic research : official publication of the Orthopaedic Research Society Gao, K. T., Pedoia, V., Young, K. A., Kogan, F., Koff, M. F., Gold, G. E., Potter, H. G., Majumdar, S. 2020

  Abstract

  Magnetic resonance imaging (MRI) is commonly used to evaluate the morphology of the knee in athletes with high knee impact; however, complex repeated loading of the joint can lead to biochemical and structural degeneration that occur prior to visible morphological changes. In this study, we utilized multiparametric quantitative MRI to compare morphology and composition of articular cartilage and subchondral bone shape between young athletes with high knee impact (basketball players; n = 40) and non-knee impact (swimmers; n = 25). We implemented voxel-based relaxometry to register all cases to a single reference space and performed localized compositional analysis of T1ρ - and T2 -relaxation times on a voxel-by-voxel basis. Additionally, statistical shape modeling was employed to extract differences in subchondral bone shape between the two groups. Evaluation of cartilage composition demonstrated significant prolongation of relaxation times in the medial femoral and tibial compartments and in the posterolateral femur of basketball players in comparison to relaxation times in the same cartilage compartments of swimmers. Compositional analysis also showed depth-dependent differences with prolongation of the superficial layer in basketball players. For subchondral bone shape, 3 total modes were found to be significantly different between groups and related to the relative sizes of the tibial plateaus, intercondylar eminences, and the curvature and concavity of the patellar lateral facet. In summary, this study identified several characteristics associated with high knee impact which may expand our understanding of local degenerative patterns in this population. This article is protected by copyright. All rights reserved.

  View details for DOI 10.1002/jor.24851

  View details for PubMedID 32910520

• Prospective Deployment of Deep Learning in MRI: A Framework for Important Considerations, Challenges, and Recommendations for Best Practices. Journal of magnetic resonance imaging : JMRI Chaudhari, A. S., Sandino, C. M., Cole, E. K., Larson, D. B., Gold, G. E., Vasanawala, S. S., Lungren, M. P., Hargreaves, B. A., Langlotz, C. P. 2020

  Abstract

  Artificial intelligence algorithms based on principles of deep learning (DL) have made a large impact on the acquisition, reconstruction, and interpretation of MRI data. Despite the large number of retrospective studies using DL, there are fewer applications of DL in the clinic on a routine basis. To address this large translational gap, we review the recent publications to determine three major use cases that DL can have in MRI, namely, that of model-free image synthesis, model-based image reconstruction, and image or pixel-level classification. For each of these three areas, we provide a framework for important considerations that consist of appropriate model training paradigms, evaluation of model robustness, downstream clinical utility, opportunities for future advances, as well recommendations for best current practices. We draw inspiration for this framework from advances in computer vision in natural imaging as well as additional healthcare fields. We further emphasize the need for reproducibility of research studies through the sharing of datasets and software. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY STAGE: 2.

  View details for DOI 10.1002/jmri.27331

  View details for PubMedID 32830874

• Time-saving opportunities in knee osteoarthritis: T2 mapping and structural imaging of the knee using a single 5-min MRI scan. European radiology Eijgenraam, S. M., Chaudhari, A. S., Reijman, M., Bierma-Zeinstra, S. M., Hargreaves, B. A., Runhaar, J., Heijboer, F. W., Gold, G. E., Oei, E. H. 2019

  Abstract

  OBJECTIVES: To assess the discriminative power of a 5-min quantitative double-echo steady-state (qDESS) sequence for simultaneous T2 measurements of cartilage and meniscus, and structural knee osteoarthritis (OA) assessment, in a clinical OA population, using radiographic knee OA as reference standard.METHODS: Fifty-three subjects were included and divided over three groups based on radiographic and clinical knee OA: 20 subjects with no OA (Kellgren-Lawrence grade (KLG) 0), 18 with mild OA (KLG2), and 15 with moderate OA (KLG3). All patients underwent a 5-min qDESS scan. We measured T2 relaxation times in four cartilage and four meniscus regions of interest (ROIs) and performed structural OA evaluation with the MRI Osteoarthritis Knee Score (MOAKS) using qDESS with multiplanar reformatting. Between-group differences in T2 values and MOAKS were calculated using ANOVA. Correlations of the reference standard (i.e., radiographic knee OA) with T2 and MOAKS were assessed with correlation analyses for ordinal variables.RESULTS: In cartilage, mean T2 values were 36.1±SD 4.3, 40.6±5.9, and 47.1±4.3ms for no, mild, and moderate OA, respectively (p<0.001). In menisci, mean T2 values were 15±3.6, 17.5±3.8, and 20.6±4.7ms for no, mild, and moderate OA, respectively (p<0.001). Statistically significant correlations were found between radiographic OA and T2 and between radiographic OA and MOAKS in all ROIs (p<0.05).CONCLUSION: Quantitative T2 and structural assessment of cartilage and meniscus, using a single 5-min qDESS scan, can distinguish between different grades of radiographic OA, demonstrating the potential of qDESS as an efficient tool for OA imaging.KEY POINTS: Quantitative T 2values of cartilage and meniscus as well as structural assessment of the knee with a single 5-min quantitative double-echo steady-state (qDESS) scan can distinguish between different grades of knee osteoarthritis (OA). Quantitative and structural qDESS-based measurements correlate significantly with the reference standard, radiographic degree of OA, for all cartilage and meniscus regions. By providing quantitative measurements and diagnostic image quality in one rapid MRI scan, qDESS has great potential for application in large-scale clinical trials in knee OA.

  View details for DOI 10.1007/s00330-019-06542-9

  View details for PubMedID 31844957

• Rapid Knee MRI Acquisition and Analysis Techniques for Imaging Osteoarthritis. Journal of magnetic resonance imaging : JMRI Chaudhari, A. S., Kogan, F., Pedoia, V., Majumdar, S., Gold, G. E., Hargreaves, B. A. 2019

  Abstract

  Osteoarthritis (OA) of the knee is a major source of disability that has no known treatment or cure. Morphological and compositional MRI is commonly used for assessing the bone and soft tissues in the knee to enhance the understanding of OA pathophysiology. However, it is challenging to extend these imaging methods and their subsequent analysis techniques to study large population cohorts due to slow and inefficient imaging acquisition and postprocessing tools. This can create a bottleneck in assessing early OA changes and evaluating the responses of novel therapeutics. The purpose of this review article is to highlight recent developments in tools for enhancing the efficiency of knee MRI methods useful to study OA. Advances in efficient MRI data acquisition and reconstruction tools for morphological and compositional imaging, efficient automated image analysis tools, and hardware improvements to further drive efficient imaging are discussed in this review. For each topic, we discuss the current challenges as well as potential future opportunities to alleviate these challenges. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY STAGE: 3.

  View details for DOI 10.1002/jmri.26991

  View details for PubMedID 31755191

• Does Injection of Hyaluronic Acid Protect Against Early Cartilage Injury Seen After Marathon Running? A Randomized Controlled Trial Utilizing High-Field Magnetic Resonance Imaging. The American journal of sports medicine Nathani, A., Gold, G. E., Monu, U., Hargreaves, B., Finlay, A. K., Rubin, E. B., Safran, M. R. 2019: 363546519879138

  Abstract

  BACKGROUND: Previous studies have shown that runners demonstrate elevated T2 and T1rho values on magnetic resonance imaging (MRI) after running a marathon, with the greatest changes in the patellofemoral and medial compartment, which can persist after 3 months of reduced activity. Additionally, marathon running has been shown to increase serum inflammatory markers. Hyaluronic acid (HA) purportedly improves viscoelasticity of synovial fluid, serving as a lubricant while also having chondroprotective and anti-inflammatory effects.PURPOSE/HYPOTHESIS: The purpose was to investigate whether intra-articular HA injection can protect articular cartilage from injury attributed to marathon running. The hypothesis was that the addition of intra-articular HA 1 week before running a marathon would reduce the magnitude of early cartilage breakdown measured by MRI.STUDY DESIGN: Randomized controlled trial; Level of evidence, 2.METHODS: After institutional review board approval, 20 runners were randomized into receiving an intra-articular injection of HA or normal saline (NS) 1 week before running a marathon. Exclusionary criteria included any prior knee injury or surgery and having run >3 prior marathons. Baseline 3-T knee MRI was obtained within 48 hours before the marathon (approximately 5 days after injection). Follow-up 3-T MRI scans of the same knee were obtained 48 to 72 hours and 3 months after the marathon. The T2 and T1rho relaxation times of articular cartilage were measured in 8 locations-the medial and lateral compartments (including 2 areas of each femoral condyle) and the patellofemoral joint. The statistical analysis compared changes in T2 and T1rho relaxation times (ms) from baseline to immediate and 3-month postmarathon scans between the HA and NS groups with repeated measures analysis of variance.RESULTS: Fifteen runners completed the study: 6 women and 2 men in the HA group (mean age, 31 years; range, 23-50 years) and 6 women and 1 man in the NS group (mean age, 27 years; range, 20-49 years). There were no gross morphologic MRI changes after running the marathon. Postmarathon studies revealed no statistically significant changes between the HA and NS groups in all articular cartilage areas of the knee on both T2 and T1rho relaxation times.CONCLUSION: Increased T2 and T1rho relaxation times have been observed in marathon runners, suggesting early cartilage injury. The addition of intra-articular HA did not significantly affect relaxation times in all areas of the knee when compared with an NS control.

  View details for DOI 10.1177/0363546519879138

  View details for PubMedID 31634003

• Assessment of acute bone loading in humans using [18F]NaF PET/MRI. European journal of nuclear medicine and molecular imaging Haddock, B., Fan, A. P., Uhlrich, S. D., Jorgensen, N. R., Suetta, C., Gold, G. E., Kogan, F. 2019

  Abstract

  PURPOSE: The acute effect of loading on bone tissue and physiology can offer important information with regard to joint function in diseases such as osteoarthritis. Imaging studies using [18F]-sodium fluoride ([18F]NaF) have found changes in tracer kinetics in animals after subjecting bones to strain, indicating an acute physiological response. The aim of this study is to measure acute changes in NaF uptake in human bone due to exercise-induced loading.METHODS: Twelve healthy subjects underwent two consecutive 50-min [18F]NaF PET/MRI examinations of the knees, one baseline followed by one post-exercise scan. Quantification of tracer kinetics was performed using an image-derived input function from the popliteal artery. For both scans, kinetic parameters of KiNLR, K1, k2, k3, and blood volume were mapped parametrically using nonlinear regression with the Hawkins model. The kinetic parameters along with mean SUV and SUVmax were compared between the pre- and post-exercise examinations. Differences in response to exercise were analysed between bone tissue types (subchondral, cortical, and trabecular bone) and between regional subsections of knee subchondral bone.RESULTS: Exercise induced a significant (p<<0.001) increase in [18F]NaF uptake in all bone tissues in both knees, with mean SUV increases ranging from 47% in trabecular bone tissue to 131% in subchondral bone tissue. Kinetic parameters involving vascularization (K1 and blood volume) increased, whereas the NaF extraction fraction [k3/(k2+k3)] was reduced.CONCLUSIONS: Bone loading induces an acute response in bone physiology as quantified by [18F]NaF PET kinetics. Dynamic imaging after bone loading using [18F]NaF PET is a promising diagnostic tool in bone physiology and imaging of biomechanics.

  View details for DOI 10.1007/s00259-019-04424-2

  View details for PubMedID 31385012

• Utility of deep learning super-resolution in the context of osteoarthritis MRI biomarkers. Journal of magnetic resonance imaging : JMRI Chaudhari, A. S., Stevens, K. J., Wood, J. P., Chakraborty, A. K., Gibbons, E. K., Fang, Z., Desai, A. D., Lee, J. H., Gold, G. E., Hargreaves, B. A. 2019

  Abstract

  BACKGROUND: Super-resolution is an emerging method for enhancing MRI resolution; however, its impact on image quality is still unknown.PURPOSE: To evaluate MRI super-resolution using quantitative and qualitative metrics of cartilage morphometry, osteophyte detection, and global image blurring.STUDY TYPE: Retrospective.POPULATION: In all, 176 MRI studies of subjects at varying stages of osteoarthritis.FIELD STRENGTH/SEQUENCE: Original-resolution 3D double-echo steady-state (DESS) and DESS with 3* thicker slices retrospectively enhanced using super-resolution and tricubic interpolation (TCI) at 3T.ASSESSMENT: A quantitative comparison of femoral cartilage morphometry was performed for the original-resolution DESS, the super-resolution, and the TCI scans in 17 subjects. A reader study by three musculoskeletal radiologists assessed cartilage image quality, overall image sharpness, and osteophytes incidence in all three sets of scans. A referenceless blurring metric evaluated blurring in all three image dimensions for the three sets of scans.STATISTICAL TESTS: Mann-Whitney U-tests compared Dice coefficients (DC) of segmentation accuracy for the DESS, super-resolution, and TCI images, along with the image quality readings and blurring metrics. Sensitivity, specificity, and diagnostic odds ratio (DOR) with 95% confidence intervals compared osteophyte detection for the super-resolution and TCI images, with the original-resolution as a reference.RESULTS: DC for the original-resolution (90.2±1.7%) and super-resolution (89.6±2.0%) were significantly higher (P<0.001) than TCI (86.3±5.6%). Segmentation overlap of super-resolution with the original-resolution (DC = 97.6±0.7%) was significantly higher (P<0.0001) than TCI overlap (DC = 95.0±1.1%). Cartilage image quality for sharpness and contrast levels, and the through-plane quantitative blur factor for super-resolution images, was significantly (P<0.001) better than TCI. Super-resolution osteophyte detection sensitivity of 80% (76-82%), specificity of 93% (92-94%), and DOR of 32 (22-46) was significantly higher (P<0.001) than TCI sensitivity of 73% (69-76%), specificity of 90% (89-91%), and DOR of 17 (13-22).DATA CONCLUSION: Super-resolution appears to consistently outperform naive interpolation and may improve image quality without biasing quantitative biomarkers.LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019.

  View details for DOI 10.1002/jmri.26872

  View details for PubMedID 31313397

• Combined 5-minute double-echo in steady-state with separated echoes and 2-minute proton-density-weighted 2D FSE sequence for comprehensive whole-joint knee MRI assessment JOURNAL OF MAGNETIC RESONANCE IMAGING Chaudhari, A. S., Stevens, K. J., Sveinsson, B., Wood, J. P., Beaulieu, C. F., Oei, E. G., Rosenberg, J. K., Kogan, F., Alley, M. T., Gold, G. E., Hargreaves, B. A. 2019; 49 (7): E183–E194

  View details for DOI 10.1002/jmri.26582

  View details for Web of Science ID 000474612300018

• Kinetic [F-18]-Fluoride of the Knee in Normal Volunteers CLINICAL NUCLEAR MEDICINE Haddock, B., Fan, A. P., Jorgensen, N. R., Suetta, C., Gold, G., Kogan, F. 2019; 44 (5): 377–85

  View details for DOI 10.1097/RLU.0000000000002533

  View details for Web of Science ID 000465173700022

• Kinetic [18F]-Fluoride of the Knee in Normal Volunteers. Clinical nuclear medicine Haddock, B., Fan, A. P., Jorgensen, N. R., Suetta, C., Gold, G. E., Kogan, F. 2019

  Abstract

  PURPOSE: [F]-sodium fluoride ([F]NaF) is a well-established bone-seeking agent that has shown promise to assess bone turnover in a variety of disorders, but its distribution in healthy knee joints has not been explored. This study aimed to investigate parametric values for [F]NaF uptake in various bone tissues types of the knee and their spatial distributions.METHODS: Twelve healthy subjects were hand-injected with 92.5 MBq of [F]NaF and scanned on a 3-T PET/MRI system. Listmode PET data for both knees were acquired for 50 minutes from injection simultaneously with MRI Dixon and angiography data. The image-derived input function was determined from the popliteal artery. Using the Hawkins model, Patlak analysis was performed to obtain Ki (Ki) values and nonlinear regression analysis to obtain Ki, K1, k3/(k2 + k3), and blood volume. Comparisons for the measured kinetic parameters, SUV, and SUVmax were made between tissue types (subchondral, cortical, and trabecular bone) and between regional subsections of subchondral bone.RESULTS: Cortical bone had the highest [F]NaF uptake differing significantly in all measured parameters when compared with trabecular bone and significantly higher SUVmax and K1 than subchondral bone. Subchondral bone also had significantly higher SUV, SUVmax, and Ki than trabecular bone tissue. Regional differences were observed in K1 and k3/(k2 + k3) values.CONCLUSIONS: Quantitative [F]NaF PET is sensitive to variations in bone vascularization and metabolism in the knee joint.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial License 4.0 (CCBY-NC), where it is permissible to download, share, remix, transform, and buildup the work provided it is properly cited. The work cannot be used commerciallywithout permission from the journal.

  View details for PubMedID 30888996

• Imaging Features of Avascular Necrosis of the Foot and Ankle. Foot and ankle clinics Couturier, S., Gold, G. 2019; 24 (1): 17–33

  Abstract

  Avascular necrosis of the foot and ankle is a rare but important cause of pain and functional abnormality. This process may occur in any bone in the foot and ankle; however, it presents most often in characteristic locations. Understanding of key radiographic findings is important in management of these lesions. MRI is the most sensitive and specific method for detection and characterization of this abnormality.

  View details for PubMedID 30685010

• Patellofemoral cartilage stresses are most sensitive to variations in vastus medialis muscle forces COMPUTER METHODS IN BIOMECHANICS AND BIOMEDICAL ENGINEERING Pal, S., Besier, T. F., Gold, G. E., Fredericson, M., Delp, S. L., Beaupre, G. S. 2019; 22 (2): 206–16

  View details for DOI 10.1080/10255842.2018.1544629

  View details for Web of Science ID 000465032000008

• Applications of PET-Computed Tomography-Magnetic Resonance in the Management of Benign Musculoskeletal Disorders. PET clinics Yoder, J. S., Kogan, F., Gold, G. E. 2019; 14 (1): 1–15

  Abstract

  Although computed tomography (CT) and MR imaging alone have been used extensively to evaluate various musculoskeletal disorders, hybrid imaging modalities of PET-CT and PET-MR imaging were recently developed, combining the advantages of each method: molecular information from PET and anatomical information from CT or MR imaging. Furthermore, different radiotracers can be used in PET to uncover different disease mechanisms. In this article, potential applications of PET-CT and PET-MR imaging for benign musculoskeletal disorders are organized by benign cell proliferation/dysplasia, diabetic foot complications, joint prostheses, degeneration, inflammation, and trauma, metabolic bone disorders, and pain (acute and chronic) and peripheral nerve imaging.

  View details for PubMedID 30420212

• Patellofemoral cartilage stresses are most sensitive to variations in vastus medialis muscle forces. Computer methods in biomechanics and biomedical engineering Pal, S., Besier, T. F., Gold, G. E., Fredericson, M., Delp, S. L., Beaupre, G. S. 2018: 1–11

  Abstract

  The purpose of this study was to evaluate the effects of variations in quadriceps muscle forces on patellofemoral stress. We created subject-specific finite element models for 21 individuals with chronic patellofemoral pain and 16 pain-free control subjects. We extracted three-dimensional geometries from high resolution magnetic resonance images and registered the geometries to magnetic resonance images from an upright weight bearing squat with the knees flexed at 60°. We estimated quadriceps muscle forces corresponding to 60° knee flexion during a stair climb task from motion analysis and electromyography-driven musculoskeletal modelling. We applied the quadriceps muscle forces to our finite element models and evaluated patellofemoral cartilage stress. We quantified cartilage stress using an energy-based effective stress, a scalar quantity representing the local stress intensity in the tissue. We used probabilistic methods to evaluate the effects of variations in quadriceps muscle forces from five trials of the stair climb task for each subject. Patellofemoral effective stress was most sensitive to variations in forces in the two branches of the vastus medialis muscle. Femur cartilage effective stress was most sensitive to variations in vastus medialis forces in 29/37 (78%) subjects, and patella cartilage effective stress was most sensitive to variations in vastus medialis forces in 21/37 (57%) subjects. Femur cartilage effective stress was more sensitive to variations in vastus medialis longus forces in subjects classified as maltrackers compared to normal tracking subjects (p=0.006). This study provides new evidence of the importance of the vastus medialis muscle in the treatment of patellofemoral pain.

  View details for PubMedID 30596523

• Combined 5-minute double-echo in steady-state with separated echoes and 2-minute proton-density-weighted 2D FSE sequence for comprehensive whole-joint knee MRI assessment. Journal of magnetic resonance imaging : JMRI Chaudhari, A. S., Stevens, K. J., Sveinsson, B., Wood, J. P., Beaulieu, C. F., Oei, E. H., Rosenberg, J. K., Kogan, F., Alley, M. T., Gold, G. E., Hargreaves, B. A. 2018

  Abstract

  BACKGROUND: Clinical knee MRI protocols require upwards of 15 minutes of scan time.PURPOSE/HYPOTHESIS: To compare the imaging appearance of knee abnormalities depicted with a 5-minute 3D double-echo in steady-state (DESS) sequence with separate echo images, with that of a routine clinical knee MRI protocol. A secondary goal was to compare the imaging appearance of knee abnormalities depicted with 5-minute DESS paired with a 2-minute coronal proton-density fat-saturated (PDFS) sequence.STUDY TYPE: Prospective.SUBJECTS: Thirty-six consecutive patients (19 male) referred for a routine knee MRI.FIELD STRENGTH/SEQUENCES: DESS and PDFS at 3T.ASSESSMENT: Five musculoskeletal radiologists evaluated all images for the presence of internal knee derangement using DESS, DESS+PDFS, and the conventional imaging protocol, and their associated diagnostic confidence of the reading.STATISTICAL TESTS: Differences in positive and negative percent agreement (PPA and NPA, respectively) and 95% confidence intervals (CIs) for DESS and DESS+PDFS compared with the conventional protocol were calculated and tested using exact McNemar tests. The percentage of observations where DESS or DESS+PDFS had equivalent confidence ratings to DESS+Conv were tested with exact symmetry tests. Interreader agreement was calculated using Krippendorff's alpha.RESULTS: DESS had a PPA of 90% (88-92% CI) and NPA of 99% (99-99% CI). DESS+PDFS had increased PPA of 99% (95-99% CI) and NPA of 100% (99-100% CI) compared with DESS (both P < 0.001). DESS had equivalent diagnostic confidence to DESS+Conv in 94% of findings, whereas DESS+PDFS had equivalent diagnostic confidence in 99% of findings (both P < 0.001). All readers had moderate concordance for all three protocols (Krippendorff's alpha 47-48%).DATA CONCLUSION: Both 1) 5-minute 3D-DESS with separated echoes and 2) 5-minute 3D-DESS paired with a 2-minute coronal PDFS sequence depicted knee abnormalities similarly to a routine clinical knee MRI protocol, which may be a promising technique for abbreviated knee MRI.LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018.

  View details for PubMedID 30582251

• PET-MRI for the Study of Metabolic Bone Disease. Current osteoporosis reports Yoder, J. S., Kogan, F., Gold, G. E. 2018

  Abstract

  PURPOSE OF REVIEW: This review article attempts to summarize the current state and applications of the hybrid imaging modality of PET-MRI to metabolic bone diseases. The advances of PET and MRI are also discussed for metabolic bone diseases as potentially applied via PET-MRI.RECENT FINDINGS: Etiologies and mechanisms of metabolic bone disease can be complex where molecular changes precede structural changes. Although PET-MRI has yet to be applied directly to metabolic bone disease, possible applications exist since PET, specifically 18F-NaF PET, can quantitatively track changes in bone metabolism and is useful for assessing treatment, while MRI can give detailed information on bone water concentration, porosity, and architecture through novel techniques such as UTE and ZTE MRI. Earlier detection and further understanding of metabolic bone disease via PET and MRI could lead to better treatment and prevention. More research using this modality is needed to further understand how it can be implemented in this realm.

  View details for PubMedID 30284705

• Applications of PET-MRI in musculoskeletal disease. Journal of magnetic resonance imaging : JMRI Kogan, F., Broski, S. M., Yoon, D., Gold, G. E. 2018; 48 (1): 27–47

  Abstract

  New integrated PET-MRI systems potentially provide a complete imaging modality for diagnosis and evaluation of musculoskeletal disease. MRI is able to provide excellent high-resolution morphologic information with multiple contrast mechanisms that has made it the imaging modality of choice in evaluation of many musculoskeletal disorders. PET offers incomparable abilities to provide quantitative information about molecular and physiologic changes that often precede structural and biochemical changes. In combination, hybrid PET-MRI can enhance imaging of musculoskeletal disorders through early detection of disease as well as improved diagnostic sensitivity and specificity. The purpose of this article is to review emerging applications of PET-MRI in musculoskeletal disease. Both clinical applications of malignant musculoskeletal disease as well as new opportunities to incorporate the molecular capabilities of nuclear imaging into studies of nononcologic musculoskeletal disease are discussed. Lastly, we discuss some of the technical considerations and challenges of PET-MRI as they specifically relate to musculoskeletal disease.LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 3 J. Magn. Reson. Imaging 2018;48:27-47.

  View details for PubMedID 29969193

• 3D Ultrashort TE MRI for Evaluation of Cartilaginous Endplate of Cervical Disk In Vivo: Feasibility and Correlation With Disk Degeneration in T2-Weighted Spin-Echo Sequence AMERICAN JOURNAL OF ROENTGENOLOGY Kim, Y., Cha, J., Shin, Y., Chaudhari, A. S., Suh, Y., Yoon, S., Gold, G. E. 2018; 210 (5): 1131–40

  Abstract

  The purpose of this study was to evaluate the feasibility of 3D ultrashort TE (UTE) MRI in depicting the cartilaginous endplate (CEP) and its abnormalities and to investigate the association between CEP abnormalities and disk degeneration on T2-weighted spin-echo (SE) MR images in cervical disks in vivo.Eight healthy volunteers and 70 patients were examined using 3-T MRI with the 3D UTE cones trajectory technique (TR/TE, 16.1/0.032, 6.6). In the volunteer study, quantitative and qualitative assessments of CEP depiction were conducted for the 3D UTE and T2-weighted SE imaging. In the patient study, CEP abnormalities were analyzed. Intersequence agreement between the images obtained with the first-echo 3D UTE sequence and the images created by subtracting the second-echo from the first-echo 3D UTE sequence (subtracted 3D UTE) and the intraobserver and interobserver agreements for 3D UTE overall were also tested. The CEP abnormalities on the 3D UTE images correlated with the Miyazaki grading of the T2-weighted SE images.In the volunteer study, the CEP was well visualized on 3D UTE images but not on T2-weighted SE images (p < 0.001). In the patient study, for evaluation of CEP abnormalities, intersequence agreements were substantial to almost perfect, intraobserver agreements were substantial to almost perfect, and interobserver agreements were moderate to substantial (p < 0.001). All of the CEP abnormalities correlated with the Miyazaki grade with statistical significance (p < 0.001).Three-dimensional UTE MRI feasibly depicts the CEP and CEP abnormalities, which may be associated with the severity of disk degeneration on T2-weighted SE MRI.

  View details for PubMedID 29629793

• Super-resolution musculoskeletal MRI using deep learning. Magnetic resonance in medicine Chaudhari, A. S., Fang, Z., Kogan, F., Wood, J., Stevens, K. J., Gibbons, E. K., Lee, J. H., Gold, G. E., Hargreaves, B. A. 2018

  Abstract

  PURPOSE: To develop a super-resolution technique using convolutional neural networks for generating thin-slice knee MR images from thicker input slices, and compare this method with alternative through-plane interpolation methods.METHODS: We implemented a 3D convolutional neural network entitled DeepResolve to learn residual-based transformations between high-resolution thin-slice images and lower-resolution thick-slice images at the same center locations. DeepResolve was trained using 124 double echo in steady-state (DESS) data sets with 0.7-mm slice thickness and tested on 17 patients. Ground-truth images were compared with DeepResolve, clinically used tricubic interpolation, and Fourier interpolation methods, along with state-of-the-art single-image sparse-coding super-resolution. Comparisons were performed using structural similarity, peak SNR, and RMS error image quality metrics for a multitude of thin-slice downsampling factors. Two musculoskeletal radiologists ranked the 3 data sets and reviewed the diagnostic quality of the DeepResolve, tricubic interpolation, and ground-truth images for sharpness, contrast, artifacts, SNR, and overall diagnostic quality. Mann-Whitney U tests evaluated differences among the quantitative image metrics, reader scores, and rankings. Cohen's Kappa (kappa) evaluated interreader reliability.RESULTS: DeepResolve had significantly better structural similarity, peak SNR, and RMS error than tricubic interpolation, Fourier interpolation, and sparse-coding super-resolution for all downsampling factors (p<.05, except 4*and 8*sparse-coding super-resolution downsampling factors). In the reader study, DeepResolve significantly outperformed (p<.01) tricubic interpolation in all image quality categories and overall image ranking. Both readers had substantial scoring agreement (kappa=0.73).CONCLUSION: DeepResolve was capable of resolving high-resolution thin-slice knee MRI from lower-resolution thicker slices, achieving superior quantitative and qualitative diagnostic performance to both conventionally used and state-of-the-art methods.

  View details for PubMedID 29582464

• Cartilage Subsurface Changes to Magnetic Resonance Imaging UTE-T2*2 Years After Anterior Cruciate Ligament Reconstruction Correlate With Walking Mechanics Associated With Knee Osteoarthritis AMERICAN JOURNAL OF SPORTS MEDICINE Titchenal, M. R., Williams, A. A., Chehab, E. F., Asay, J. L., Dragoo, J. L., Gold, G. E., McAdams, T. R., Andriacchi, T. P., Chu, C. R. 2018; 46 (3): 565–72

  Abstract

  Anterior cruciate ligament (ACL) injury increases risk for posttraumatic knee osteoarthritis (OA). Quantitative ultrashort echo time enhanced T2* (UTE-T2*) mapping shows promise for early detection of potentially reversible subsurface cartilage abnormalities after ACL reconstruction (ACLR) but needs further validation against established clinical metrics of OA risk such as knee adduction moment (KAM) and mechanical alignment.Elevated UTE-T2* values in medial knee cartilage 2 years after ACLR correlate with varus alignment and higher KAM during walking.Cohort study (diagnosis); Level of evidence, 2.Twenty patients (mean age, 33.1 ± 10.5 years; 11 female) 2 years after ACLR underwent 3.0-T knee magnetic resonance imaging (MRI), radiography, and gait analysis, after which mechanical alignment was measured, KAM during walking was calculated, and UTE-T2* maps were generated. The mechanical axis and the first and second peaks of KAM (KAM1 and KAM2, respectively) were tested using linear regressions for correlations with deep UTE-T2* values in the central and posterior medial femoral condyle (cMFC and pMFC, respectively) and central medial tibial plateau (cMTP). UTE-T2* values from ACL-reconstructed patients were additionally compared with those of 14 uninjured participants (mean age, 30.9 ± 8.9 years; 6 female) using Mann-Whitney U and standard t tests.Central weightbearing medial compartment cartilage of ACL-reconstructed knees was intact on morphological MRI. Mean UTE-T2* values were elevated in both the cMFC and pMFC of ACL-reconstructed knees compared with those of uninjured knees ( P = .003 and P = .012, respectively). In ACL-reconstructed knees, UTE-T2* values of cMFC cartilage positively correlated with increasing varus alignment ( R = 0.568). Higher UTE-T2* values in cMFC and cMTP cartilage of ACL-reconstructed knees also correlated with greater KAM1 ( R = 0.452 and R = 0.463, respectively) and KAM2 ( R = 0.465 and R = 0.764, respectively) and with KAM2 in pMFC cartilage ( R = 0.602).Elevated deep UTE-T2* values of medial knee cartilage 2 years after ACLR correlate with 2 clinical markers of increased risk of medial knee OA. These results support the clinical utility of MRI UTE-T2* for early diagnosis of subsurface cartilage abnormalities. Longitudinal follow-up of larger cohorts is needed to determine the predictive and staging potential of UTE-T2* for posttraumatic OA.

  View details for PubMedID 29293364

• Value of MRI in medicine: More than just another test? Journal of magnetic resonance imaging : JMRI van Beek, E. J., Kuhl, C., Anzai, Y., Desmond, P., Ehman, R. L., Gong, Q., Gold, G., Gulani, V., Hall-Craggs, M., Leiner, T., Lim, C. C., Pipe, J. G., Reeder, S., Reinhold, C., Smits, M., Sodickson, D. K., Tempany, C., Vargas, H. A., Wang, M. 2018

  Abstract

  There is increasing scrutiny from healthcare organizations towards the utility and associated costs of imaging. MRI has traditionally been used as a high-end modality, and although shown extremely important for many types of clinical scenarios, it has been suggested as too expensive by some. This editorial will try and explain how value should be addressed and gives some insights and practical examples of how value of MRI can be increased. It requires a global effort to increase accessibility, value for money, and impact on patient management. We hope this editorial sheds some light and gives some indications of where the field may wish to address some of its research to proactively demonstrate the value of MRI.5 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2018.

  View details for PubMedID 30145852

• Deep Learning Super-Resolution Enables Rapid Simultaneous Morphological and Quantitative Magnetic Resonance Imaging Chaudhari, A., Fang, Z., Lee, J., Gold, G., Hargreaves, B., Knoll, F., Maier, A., Rueckert, D. SPRINGER INTERNATIONAL PUBLISHING AG. 2018: 3–11

  View details for DOI 10.1007/978-3-030-00129-2_1

  View details for Web of Science ID 000477767500001

• Detecting Anatomical Landmarks for Motion Estimation in Weight-Bearing Imaging of Knees Bier, B., Aschoff, K., Syben, C., Unberath, M., Levenston, M., Gold, G., Fahrig, R., Maier, A., Knoll, F., Maier, A., Rueckert, D. SPRINGER INTERNATIONAL PUBLISHING AG. 2018: 83–90

  View details for DOI 10.1007/978-3-030-00129-2_10

  View details for Web of Science ID 000477767500010

• SNR-weighted regularization of ADC estimates from double-echo in steady-state (DESS). Magnetic resonance in medicine Sveinsson, B., Gold, G. E., Hargreaves, B. A., Yoon, D. 2018

  Abstract

  To improve the homogeneity and consistency of apparent diffusion coefficient (ADC) estimates in cartilage from the double-echo in steady-state (DESS) sequence by applying SNR-weighted regularization during post-processing.An estimation method that linearizes ADC estimates from DESS is used in conjunction with a smoothness constraint to suppress noise-induced variation in ADC estimates. Simulations, phantom scans, and in vivo scans are used to demonstrate how the method reduces ADC variability. Conventional diffusion-weighted echo-planar imaging (DW EPI) maps are acquired for comparison of mean and standard deviation (SD) of the ADC estimate.Simulations and phantom scans demonstrated that the SNR-weighted regularization can produce homogenous ADC maps at varying levels of SNR, whereas non-regularized maps only estimate ADC accurately at high SNR levels. The in vivo maps showed that the SNR-weighted regularization produced ADC maps with similar heterogeneity to maps produced with standard DW EPI, but without the distortion of such reference scans.A linear approximation of a simplified model of the relationship between DESS signals allows for fast SNR-weighted regularization of ADC maps that reduces estimation error in relatively short T2 tissue such as cartilage.

  View details for PubMedID 30125389

• Simultaneous bilateral-knee MR imaging. Magnetic resonance in medicine Kogan, F., Levine, E., Chaudhari, A. S., Monu, U. D., Epperson, K., Oei, E. H., Gold, G. E., Hargreaves, B. A. 2018; 80 (2): 529–37

  Abstract

  To demonstrate and evaluate the scan time and quantitative accuracy of simultaneous bilateral-knee imaging compared with single-knee acquisitions.Hardware modifications and safety testing was performed to enable MR imaging with two 16-channel flexible coil arrays. Noise covariance and sensitivity-encoding g-factor maps for the dual-coil-array configuration were computed to evaluate coil cross-talk and noise amplification. Ten healthy volunteers were imaged on a 3T MRI scanner with both dual-coil-array bilateral-knee and single-coil-array single-knee configurations. Two experienced musculoskeletal radiologists compared the relative image quality between blinded image pairs acquired with each configuration. Differences in T2 relaxation time measurements between dual-coil-array and single-coil-array acquisitions were compared with the standard repeatability of single-coil-array measurements using a Bland-Altman analysis.The mean g-factors for the dual-coil-array configuration were low for accelerations up to 6 in the right-left direction, and minimal cross-talk was observed between the two coil arrays. Image quality ratings of various joint tissues showed no difference in 89% (95% confidence interval: 85-93%) of rated image pairs, with only small differences ("slightly better" or "slightly worse") in image quality observed. The T2 relaxation time measurements between the dual-coil-array configuration and the single-coil configuration showed similar limits of agreement and concordance correlation coefficients (limits of agreement: -0.93 to 1.99 ms; CCC: 0.97 (95% confidence interval: 0.96-0.98)), to the repeatability of single-coil-array measurements (limits of agreement: -2.07 to 1.96 ms; CCC: 0.97 (95% confidence interval: 0.95-0.98)).A bilateral coil-array setup can image both knees simultaneously in similar scan times as conventional unilateral knee scans, with comparable image quality and quantitative accuracy. This has the potential to improve the value of MRI knee evaluations. Magn Reson Med 80:529-537, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

  View details for PubMedID 29250856

  View details for PubMedCentralID PMC5910219

• Five-minute knee MRI for simultaneous morphometry and T2 relaxometry of cartilage and meniscus and for semiquantitative radiological assessment using double-echo in steady-state at 3T. Journal of magnetic resonance imaging : JMRI Chaudhari, A. S., Black, M. S., Eijgenraam, S., Wirth, W., Maschek, S., Sveinsson, B., Eckstein, F., Oei, E. H., Gold, G. E., Hargreaves, B. A. 2018; 47 (5): 1328–41

  Abstract

  Biomarkers for assessing osteoarthritis activity necessitate multiple MRI sequences with long acquisition times.To perform 5-minute simultaneous morphometry (thickness/volume measurements) and T2 relaxometry of both cartilage and meniscus, and semiquantitative MRI Osteoarthritis Knee Scoring (MOAKS).Prospective.Fifteen healthy volunteers for morphometry and T2 measurements, and 15 patients (five each Kellgren-Lawrence grades 0/2/3) for MOAKS assessment.A 5-minute double-echo steady-state (DESS) sequence was evaluated for generating quantitative and semiquantitative osteoarthritis biomarkers at 3T.Flip angle simulations evaluated tissue signals and sensitivity of T2 measurements. Morphometry and T2 reproducibility was compared against morphometry-optimized and relaxometry-optimized sequences. Repeatability was assessed by scanning five volunteers twice. MOAKS reproducibility was compared to MOAKS derived from a clinical knee MRI protocol by two readers.Coefficients of variation (CVs), concordance confidence intervals (CCI), and Wilcoxon signed-rank tests compared morphometry and relaxometry measurements with their reference standards. DESS MOAKS positive percent agreement (PPA), negative percentage agreement (NPA), and interreader agreement was calculated using the clinical protocol as a reference. Biomarker variations between Kellgren-Lawrence groups were evaluated using Wilcoxon rank-sum tests.Cartilage thickness (P = 0.65), cartilage T2 (P = 0.69), and meniscus T2 (P = 0.06) did not significantly differ from their reference standard (with a 20° DESS flip angle). DESS slightly overestimated meniscus volume (P < 0.001). Accuracy and repeatability CVs were <3.3%, except the meniscus T2 accuracy (7.6%). DESS MOAKS had substantial interreader agreement and high PPA/NPA values of 87%/90%. Bone marrow lesions and menisci had slightly lower PPAs. Cartilage and meniscus T2 , and MOAKS (cartilage surface area, osteophytes, cysts, and total score) was higher in Kellgren-Lawrence groups 2 and 3 than group 0 (P < 0.05).The 5-minute DESS sequence permits MOAKS assessment for a majority of tissues, along with repeatable and reproducible simultaneous cartilage and meniscus T2 relaxometry and morphometry measurements.2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:1328-1341.

  View details for PubMedID 29090500

  View details for PubMedCentralID PMC5899635

• Range Imaging for Motion Compensation in C-Arm Cone-Beam CT of Knees under Weight-Bearing Conditions JOURNAL OF IMAGING Bier, B., Ravikumar, N., Unberath, M., Levenston, M., Gold, G., Fahrig, R., Maier, A. 2018; 4 (1)

  View details for DOI 10.3390/jimaging4010013

  View details for Web of Science ID 000424412600013

• Low-intensity Vibration Therapy for Bone Health in Renal Osteodystrophy ACADEMIC RADIOLOGY Sharma, S., Gold, G. E. 2017; 24 (11): 1329–31

  View details for DOI 10.1016/j.acra.2017.08.001

  View details for Web of Science ID 000413992500001

  View details for PubMedID 28927580

• PET/MRI of Metabolic Activity in Osteoarthritis: A Feasibility Study JOURNAL OF MAGNETIC RESONANCE IMAGING Kogan, F., Fan, A. P., McWalter, E. J., Oei, E. H., Quon, A., Gold, G. E. 2017; 45 (6): 1736-1745

  Abstract

  To evaluate positron emission tomography / magnetic resonance imaging (PET/MRI) knee imaging to detect and characterize osseous metabolic abnormalities and correlate PET radiotracer uptake with osseous abnormalities and cartilage degeneration observed on MRI.Both knees of 22 subjects with knee pain or injury were scanned at one timepoint, without gadolinium, on a hybrid 3.0T PET-MRI system following injection of (18) F-fluoride or (18) F-fluorodeoxyglucose (FDG). A musculoskeletal radiologist identified volumes of interest (VOIs) around bone abnormalities on MR images and scored bone marrow lesions (BMLs) and osteophytes using a MOAKS scoring system. Cartilage appearance adjacent to bone abnormalities was graded with MRI-modified Outerbridge classifications. On PET standardized uptake values (SUV) maps, VOIs with SUV greater than 5 times the SUV in normal-appearing bone were identified as high-uptake VOI (VOIHigh ). Differences in (18) F-fluoride uptake between bone abnormalities, BML, and osteophyte grades and adjacent cartilage grades on MRI were identified using Mann-Whitney U-tests.SUVmax in all subchondral bone lesions (BML, osteophytes, sclerosis) was significantly higher than that of normal-appearing bone on MRI (P < 0.001 for all). Of the 172 high-uptake regions on (18) F-fluoride PET, 63 (37%) corresponded to normal-appearing subchondral bone on MRI. Furthermore, many small grade 1 osteophytes (40 of 82 [49%]), often described as the earliest signs of osteoarthritis (OA), did not show high uptake. Lastly, PET SUVmax in subchondral bone adjacent to grade 0 cartilage was significantly lower compared to that of grades 1-2 (P < 0.05) and grades 3-4 cartilage (P < 0.001).PET/MRI can simultaneously assess multiple early metabolic and morphologic markers of knee OA across multiple tissues in the joint. Our findings suggest that PET/MR may detect metabolic abnormalities in subchondral bone, which appear normal on MRI.2 J. Magn. Reson. Imaging 2016.

  View details for DOI 10.1002/jmri.25529

  View details for Web of Science ID 000401259900018

• A simple analytic method for estimating T2 in the knee from DESS MAGNETIC RESONANCE IMAGING Sveinsson, B., Chaudhari, A. S., Gold, G. E., Hargreaves, B. A. 2017; 38: 63-70

  Abstract

  To introduce a simple analytical formula for estimating T2 from a single Double-Echo in Steady-State (DESS) scan.Extended Phase Graph (EPG) modeling was used to develop a straightforward linear approximation of the relationship between the two DESS signals, enabling accurate T2 estimation from one DESS scan. Simulations were performed to demonstrate cancellation of different echo pathways to validate this simple model. The resulting analytic formula was compared to previous methods for T2 estimation using DESS and fast spin-echo scans in agar phantoms and knee cartilage in three volunteers and three patients. The DESS approach allows 3D (256×256×44) T2-mapping with fat suppression in scan times of 3-4min.The simulations demonstrated that the model approximates the true signal very well. If the T1 is within 20% of the assumed T1, the T2 estimation error was shown to be less than 5% for typical scans. The inherent residual error in the model was demonstrated to be small both due to signal decay and opposing signal contributions. The estimated T2 from the linear relationship agrees well with reference scans, both for the phantoms and in vivo. The method resulted in less underestimation of T2 than previous single-scan approaches, with processing times 60 times faster than using a numerical fit.A simplified relationship between the two DESS signals allows for rapid 3D T2 quantification with DESS that is accurate, yet also simple. The simplicity of the method allows for immediate T2 estimation in cartilage during the MRI examination.

  View details for DOI 10.1016/j.mri.2016.12.018

  View details for Web of Science ID 000398008700010

  View details for PubMedCentralID PMC5360502

• Cluster analysis of quantitative MRI T-2 and T-1 rho relaxation times of cartilage identifies differences between healthy and ACL-injured individuals at 3T OSTEOARTHRITIS AND CARTILAGE Monu, U. D., Jordan, C. D., Samuelson, B. L., Hargreaves, B. A., Gold, G. E., McWalter, E. J. 2017; 25 (4): 513-520

  Abstract

  To identify focal lesions of elevated MRI T2 and T1ρ relaxation times in articular cartilage of an ACL-injured group using a novel cluster analysis technique.Eighteen ACL-injured patients underwent 3T MRI T2 and T1ρ relaxometry at baseline, 6 months and 1 year and six healthy volunteers at baseline, 1 day and 1 year. Clusters of contiguous pixels above or below T2 and T1ρ intensity and area thresholds were identified on a projection map of the 3D femoral cartilage surface. The total area of femoral cartilage plate covered by clusters (%CA) was split into areas above (%CA+) and below (%CA-) the thresholds and the differences in %CA(+ or -) over time in the ACL-injured group were determined using the Wilcoxon signed rank test.%CA+ was greater in the ACL-injured patients than the healthy volunteers at 6 months and 1 year with average %CA+ of 5.2 ± 4.0% (p = 0.0054) and 6.6 ± 3.7% (p = 0.0041) for T2 and 6.2 ± 7.1% (p = 0.063) and 8.2 ± 6.9% (p = 0.042) for T1ρ, respectively. %CA- at 6 months and 1 year was 3.0 ± 1.8% (p > 0.1) and 5.9 ± 5.0% (p > 0.1) for T2 and 4.4 ± 4.9% (p > 0.1) and 4.5 ± 4.6% (p > 0.1) for T1ρ, respectively.With the proposed cluster analysis technique, we have quantified cartilage lesion coverage and demonstrated that the ACL-injured group had greater areas of elevated T2 and T1ρ relaxation times as compared to healthy volunteers.

  View details for DOI 10.1016/j.joca.2016.09.015

  View details for Web of Science ID 000401093200015

• Volumetric Multislice GagCEST Imaging of Articular Cartilage: Optimization and Comparison With T1rho MAGNETIC RESONANCE IN MEDICINE Kogan, F., Hargreaves, B. A., Gold, G. E. 2017; 77 (3): 1134-1141

  Abstract

  To develop and optimize a multislice glycosaminoglycan (GAG) chemical exchange saturation transfer (GagCEST) sequence for volumetric imaging of articular cartilage, and to validate the sequence against T1ρ relaxation times in whole joint imaging of tibiotalar cartilage.Ex vivo experiments were used to observe the effect of the number of partitions and shot TR on signal-to-noise ratio and measured GagCESTasym . GagCEST imaging of the entire tibiotalar joint was also performed on 10 healthy subjects. The measured GagCESTasym was compared and correlated with T1ρ relaxation times.Ex vivo studies showed a higher average GagCESTasym from articular cartilage on multislice acquisitions acquired with two or more partitions than observed with a single-slice acquisition. In healthy human subjects, an average GagCESTasym of 8.8 ± 0.7% was observed. A coefficient of variation of GagCESTasym across slices of less than 15% was seen for all subjects. Across subjects, a Pearson correlation coefficient of -0.58 was observed between the measured gagCESTasym and T1ρ relaxation times.We demonstrated the feasibility and optimization of multislice GagCEST mapping of articular cartilage. Volumetric analysis and decreased scan times will help to advance the clinical utility of GagCEST imaging of articular cartilage. Magn Reson Med, 2016. © 2016 Wiley Periodicals, Inc.

  View details for DOI 10.1002/mrm.26200

  View details for Web of Science ID 000397407800022

• Anatomically-standardized maps reveal distinct patterns of cartilage thickness with increasing severity of medial compartment knee osteoarthritis. Journal of orthopaedic research Favre, J., Erhart-Hledik, J. C., Blazek, K., Fasel, B., Gold, G. E., Andriacchi, T. P. 2017

  Abstract

  While cartilage thickness alterations are a central element of knee osteoarthritis (OA), differences among disease stages are still incompletely understood. This study aimed to quantify the spatial-variations in cartilage thickness using anatomically standardized thickness maps and test if there are characteristic patterns in patients with different stages of medial compartment knee OA. Magnetic resonance images were acquired for 75 non-OA and 100 OA knees of varying severities (Kellgren and Lawrence (KL) scores 1-4). Three-dimensional cartilage models were reconstructed and a shape matching technique was applied to convert the models into two-dimensional anatomically standardized thickness maps. Difference thickness maps and statistical parametric mapping were used to compare the four OA and the non-OA subgroups. This analysis showed distinct thickness patterns for each clinical stage that formed a coherent succession from the non-OA to the KL 4 subgroups. Interestingly, the only significant difference for early stage (KL 1) was thicker femoral cartilage. With increase in disease severity, typical patterns developed, including thinner cartilage in the anterior area of the medial condyle (significant for KL 3 and 4) and thicker cartilage in the posterior area of the medial and lateral condyles (significant for all OA subgroups). The tibial patterns mainly consisted of thinner cartilage for both medial and lateral compartments (significant for KL 2-4). Comparing anatomically standardized maps allowed identifying patterns of thickening and thinning over the entire cartilage surface, consequently improving the characterization of thickness differences associated with OA. The results also highlighted the value of anatomically standardized maps to analyze spatial variations in cartilage thickness. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

  View details for DOI 10.1002/jor.23548

  View details for PubMedID 28233332

• Magnetic resonance-guided focused ultrasound treatment of extra-abdominal desmoid tumors: a retrospective multicenter study EUROPEAN RADIOLOGY Ghanouni, P., Dobrotwir, A., Bazzocchi, A., Bucknor, M., Bitton, R., Rosenberg, J., Telischak, K., Busacca, M., Ferrari, S., Albisinni, U., Walters, S., Gold, G., Ganjoo, K., Napoli, A., Pauly, K. B., Avedian, R. 2017; 27 (2): 732-740

  Abstract

  To assess the feasibility, safety and preliminary efficacy of magnetic resonance-guided focused ultrasound (MRgFUS) for the treatment of extra-abdominal desmoid tumours.Fifteen patients with desmoid fibromatosis (six males, nine females; age range, 7-66 years) were treated with MRgFUS, with seven patients requiring multiple treatments (25 total treatments). Changes in viable and total tumour volumes were measured after treatment. Efficacy was evaluated using an exact one-sided Wilcoxon test to determine if the median reduction in viable tumour measured immediately after initial treatment exceeded a threshold of 50 % of the targeted volume. Median decrease after treatment of at least two points in numerical rating scale (NRS) worst and average pain scores was tested with an exact one-sided Wilcoxon test. Adverse events were recorded.After initial MRgFUS treatment, median viable targeted tumour volume decreased 63 %, significantly beyond our efficacy threshold (P = 0.0013). Median viable total tumour volume decreased (105 mL [interquartile range {IQR}, 217 mL] to 54 mL [IQR, 92 mL]) and pain improved (worst scores, 7.5 ± 1.9 vs 2.7 ± 2.6, P = 0.027; average scores, 6 ± 2.3 vs 1.3 ± 2, P = 0.021). Skin burn was the most common complication.MRgFUS significantly and durably reduced viable tumour volume and pain in this series of 15 patients with extra-abdominal desmoid fibromatosis.• Retrospective four-centre study shows MRgFUS safely and effectively treats extra-abdominal desmoid tumours • This non-invasive procedure can eradicate viable tumour in some cases • Alternatively, MRgFUS can provide durable control of tumour growth through repeated treatments • Compared to surgery or radiation, MRgFUS has relatively mild side effects.

  View details for DOI 10.1007/s00330-016-4376-5

  View details for Web of Science ID 000392142000034

• connective tissues in the knee using ultrashort echo-time double-echo steady-state (UTEDESS). Magnetic resonance in medicine Chaudhari, A. S., Sveinsson, B., Moran, C. J., McWalter, E. J., Johnson, E. M., Zhang, T., Gold, G. E., Hargreaves, B. A. 2017

  Abstract

  To develop a radial, double-echo steady-state (DESS) sequence with ultra-short echo-time (UTE) capabilities for T2 measurement of short-T2 tissues along with simultaneous rapid, signal-to-noise ratio (SNR)-efficient, and high-isotropic-resolution morphological knee imaging.THe 3D radial UTE readouts were incorporated into DESS, termed UTEDESS. Multiple-echo-time UTEDESS was used for performing T2 relaxometry for short-T2 tendons, ligaments, and menisci; and for Dixon water-fat imaging. In vivo T2 estimate repeatability and SNR efficiency for UTEDESS and Cartesian DESS were compared. The impact of coil combination methods on short-T2 measurements was evaluated by means of simulations. UTEDESS T2 measurements were compared with T2 measurements from Cartesian DESS, multi-echo spin-echo (MESE), and fast spin-echo (FSE).UTEDESS produced isotropic resolution images with high SNR efficiency in all short-T2 tissues. Simulations and experiments demonstrated that sum-of-squares coil combinations overestimated short-T2 measurements. UTEDESS measurements of meniscal T2 were comparable to DESS, MESE, and FSE measurements while the tendon and ligament measurements were less biased than those from Cartesian DESS. Average UTEDESS T2 repeatability variation was under 10% in all tissues.The T2 measurements of short-T2 tissues and high-resolution morphological imaging provided by UTEDESS makes it promising for studying the whole knee, both in routine clinical examinations and longitudinal studies. Magn Reson Med, 2017. © 2017 International Society for Magnetic Resonance in Medicine.

  View details for DOI 10.1002/mrm.26577

  View details for PubMedID 28074498

• Perfusion has no effect on the in vivo CEST effect from Cr (CrCEST) in skeletal muscle. NMR in biomedicine Kogan, F., Stafford, R. B., Englund, E. K., Gold, G. E., Hariharan, H., Detre, J. A., Reddy, R. 2017; 30 (1)

  Abstract

  Creatine, a key component of muscle energy metabolism, exhibits a chemical exchange saturation transfer (CEST) effect between its amine group and bulk water, which has been exploited to spatially and temporally map creatine changes in skeletal muscle before and after exercise. In addition, exercise leads to an increase in muscle perfusion. In this work, we determined the effects of perfused blood on the CEST effects from creatine in skeletal muscle. Experiments were performed on healthy human subjects (n = 5) on a whole-body Siemens 7T magnetic resonance imaging (MRI) scanner with a 28-channel radiofrequency (RF) coil. Reactive hyperemia, induced by inflation and subsequent deflation of a pressure cuff secured around the thigh, was used to increase tissue perfusion whilst maintaining the levels of creatine kinase metabolites. CEST, arterial spin labeling (ASL) and (31) P MRS data were acquired at baseline and for 6 min after cuff deflation. Reactive hyperemia resulted in substantial increases in perfusion in human skeletal muscle of the lower leg as measured by the ASL mean percentage difference. However, no significant changes in CrCEST asymmetry (CrCESTasym ) or (31) P MRS-derived PCr levels of skeletal muscle were observed following cuff deflation. This work demonstrates that perfusion changes do not have a major confounding effect on CrCEST measurements.

  View details for DOI 10.1002/nbm.3673

  View details for PubMedID 27898185

• Comparison of Different Approaches for Measuring Tibial Cartilage Thickness JOURNAL OF INTEGRATIVE BIOINFORMATICS Maier, J., Black, M., Bonaretti, S., Bier, B., Eskofier, B., Choi, J., Levenston, M., Gold, G., Fahrig, R., Maier, A. 2017; 14 (2)

  Abstract

  Osteoarthritis is a degenerative disease affecting bones and cartilage especially in the human knee. In this context, cartilage thickness is an indicator for knee cartilage health. Thickness measurements are performed on medical images acquired in-vivo. Currently, there is no standard method agreed upon that defines a distance measure in articular cartilage. In this work, we present a comparison of different methods commonly used in literature. These methods are based on nearest neighbors, surface normal vectors, local thickness and potential field lines. All approaches were applied to manual segmentations of tibia and lateral and medial tibial cartilage performed by experienced raters. The underlying data were contrast agent-enhanced cone-beam C-arm CT reconstructions of one healthy subject's knee. The subject was scanned three times, once in supine position and two times in a standing weight-bearing position. A comparison of the resulting thickness maps shows similar distributions and high correlation coefficients between the approaches above 0.90. The nearest neighbor method results on average in the lowest cartilage thickness values, while the local thickness approach assigns the highest values. We showed that the different methods agree in their thickness distribution. The results will be used for a future evaluation of cartilage change under weight-bearing conditions.

  View details for DOI 10.1515/jib-2017-0015

  View details for Web of Science ID 000406931200005

  View details for PubMedID 28753537

• Evaluation of hip abductor and adductor strength in the elderly: a reliability study. European review of aging and physical activity Gafner, S., Bastiaenen, C. H., Terrier, P., Punt, I., Ferrari, S., Gold, G., de Bie, R., Allet, L. 2017; 14: 5-?

  Abstract

  In elderly individuals an increased muscle strength contributes to the diminution of the falls risk and associated adverse events. An increasing interest in lateral control exists due to the fatal consequences of postero-lateral falls. Therefore a proper assessment of frontal plane hip muscle strength in elderly is important but remains challenging. Therefore we aimed to investigate the feasibility and repeatability of a hip abductor and adductor maximum voluntary isometric strength (MVIS) and rate of force generation (RFG) test in elderly. This represents an initial step in the development process of a new and clinically relevant test that could lead to more specific treatment protocols for this population.In this measurement focused study hip abduction (ABD) and adduction (ADD) MVIS and RFG were tested twice within one to three hours with a dynamometer fixed to a custom made frame in a geriatric population including fallers and non-fallers. Intraclass correlation coefficient (ICCagreement), standard error of measurement (SEM), and smallest detectable difference (SDD) were determined.All recruited persons (N = 76; mean age (SD) 80.46 (7.05) years old) completed the tests. The average time needed to complete the strength tests was 10.58 min. (1.56) per muscle group. The reliability of the hip ABD and ADD was high with ICC'sagreement ranging from 0.83 to 0.97. The SDD varied between 18.1 and 81.8% depending on the muscle group and type of strength that was evaluated.Hip abductor and adductor strength measures in older person are feasible and reliable. However, the significance of moderate changes in these measurements may be limited by the large SDD and SEM. Therefore, physical therapist should be careful when using this measure for assessing the progress of an individual person in a daily clinical use.

  View details for DOI 10.1186/s11556-017-0174-6

  View details for PubMedID 28450961

• A simple analytic method for estimating T2 in the knee from DESS. Magnetic resonance imaging SVEINSSON, B., Chaudhari, A. S., Gold, G. E., Hargreaves, B. A. 2016; 38: 63-70

  Abstract

  To introduce a simple analytical formula for estimating T2 from a single Double-Echo in Steady-State (DESS) scan.Extended Phase Graph (EPG) modeling was used to develop a straightforward linear approximation of the relationship between the two DESS signals, enabling accurate T2 estimation from one DESS scan. Simulations were performed to demonstrate cancellation of different echo pathways to validate this simple model. The resulting analytic formula was compared to previous methods for T2 estimation using DESS and fast spin-echo scans in agar phantoms and knee cartilage in three volunteers and three patients. The DESS approach allows 3D (256×256×44) T2-mapping with fat suppression in scan times of 3-4min.The simulations demonstrated that the model approximates the true signal very well. If the T1 is within 20% of the assumed T1, the T2 estimation error was shown to be less than 5% for typical scans. The inherent residual error in the model was demonstrated to be small both due to signal decay and opposing signal contributions. The estimated T2 from the linear relationship agrees well with reference scans, both for the phantoms and in vivo. The method resulted in less underestimation of T2 than previous single-scan approaches, with processing times 60 times faster than using a numerical fit.A simplified relationship between the two DESS signals allows for rapid 3D T2 quantification with DESS that is accurate, yet also simple. The simplicity of the method allows for immediate T2 estimation in cartilage during the MRI examination.

  View details for DOI 10.1016/j.mri.2016.12.018

  View details for PubMedID 28017730

  View details for PubMedCentralID PMC5360502

• Potential of PET-MRI for imaging of non-oncologic musculoskeletal disease. Quantitative imaging in medicine and surgery Kogan, F., Fan, A. P., Gold, G. E. 2016; 6 (6): 756-771

  Abstract

  Early detection of musculoskeletal disease leads to improved therapies and patient outcomes, and would benefit greatly from imaging at the cellular and molecular level. As it becomes clear that assessment of multiple tissues and functional processes are often necessary to study the complex pathogenesis of musculoskeletal disorders, the role of multi-modality molecular imaging becomes increasingly important. New positron emission tomography-magnetic resonance imaging (PET-MRI) systems offer to combine high-resolution MRI with simultaneous molecular information from PET to study the multifaceted processes involved in numerous musculoskeletal disorders. In this article, we aim to outline the potential clinical utility of hybrid PET-MRI to these non-oncologic musculoskeletal diseases. We summarize current applications of PET molecular imaging in osteoarthritis (OA), rheumatoid arthritis (RA), metabolic bone diseases and neuropathic peripheral pain. Advanced MRI approaches that reveal biochemical and functional information offer complementary assessment in soft tissues. Additionally, we discuss technical considerations for hybrid PET-MR imaging including MR attenuation correction, workflow, radiation dose, and quantification.

  View details for DOI 10.21037/qims.2016.12.16

  View details for PubMedID 28090451

• Magnetic Resonance Imaging of Asymptomatic Knees in Collegiate Basketball Players: The Effect of One Season of Play. Clinical journal of sport medicine Pappas, G. P., Vogelsong, M. A., Staroswiecki, E., Gold, G. E., Safran, M. R. 2016; 26 (6): 483-489

  Abstract

  To determine the prevalence of abnormal structural findings using 3.0-T magnetic resonance imaging (MRI) in the asymptomatic knees of male and female collegiate basketball players before and after a season of high-intensity basketball.Institutional review board-approved prospective case series.Asymptomatic knees of 24 NCAA Division I collegiate basketball players (12 male, 12 female) were imaged using a 3.0-T MRI scanner before and after the end of the competitive season. Three subjects did not undergo scanning after the season.Images were evaluated for prepatellar bursitis, fat pad edema, patellar and quadriceps tendinopathy, bone marrow edema, and articular cartilage and meniscal injury.Every knee imaged had at least 1 structural abnormality both preseason and postseason. A high preseason and postseason prevalence of fat pad edema (75% and 81%), patellar tendinopathy (83% and 90%), and quadriceps tendinopathy (75% and 90%) was seen. Intrameniscal signal change was observed in 50% preseason knees and 62% of postseason knees, but no discrete tears were found. Bone marrow edema was seen in 75% and 86% of knees in the preseason and postseason, respectively. Cartilage findings were observed in 71% and 81% of knees in the preseason and postseason, respectively. The cartilage injury score increased significantly in the postseason compared with the preseason (P = 0.0009).A high prevalence of abnormal knee MRI findings was observed in a population of asymptomatic young elite athletes. These preliminary data suggest that high-intensity basketball may have potentially deleterious effects on articular cartilage.

  View details for PubMedID 27347867

• PET/MRI of metabolic activity in osteoarthritis: A feasibility study. Journal of magnetic resonance imaging : JMRI Kogan, F., Fan, A. P., McWalter, E. J., Oei, E. H., Quon, A., Gold, G. E. 2016

  Abstract

  To evaluate positron emission tomography / magnetic resonance imaging (PET/MRI) knee imaging to detect and characterize osseous metabolic abnormalities and correlate PET radiotracer uptake with osseous abnormalities and cartilage degeneration observed on MRI.Both knees of 22 subjects with knee pain or injury were scanned at one timepoint, without gadolinium, on a hybrid 3.0T PET-MRI system following injection of (18) F-fluoride or (18) F-fluorodeoxyglucose (FDG). A musculoskeletal radiologist identified volumes of interest (VOIs) around bone abnormalities on MR images and scored bone marrow lesions (BMLs) and osteophytes using a MOAKS scoring system. Cartilage appearance adjacent to bone abnormalities was graded with MRI-modified Outerbridge classifications. On PET standardized uptake values (SUV) maps, VOIs with SUV greater than 5 times the SUV in normal-appearing bone were identified as high-uptake VOI (VOIHigh ). Differences in (18) F-fluoride uptake between bone abnormalities, BML, and osteophyte grades and adjacent cartilage grades on MRI were identified using Mann-Whitney U-tests.SUVmax in all subchondral bone lesions (BML, osteophytes, sclerosis) was significantly higher than that of normal-appearing bone on MRI (P < 0.001 for all). Of the 172 high-uptake regions on (18) F-fluoride PET, 63 (37%) corresponded to normal-appearing subchondral bone on MRI. Furthermore, many small grade 1 osteophytes (40 of 82 [49%]), often described as the earliest signs of osteoarthritis (OA), did not show high uptake. Lastly, PET SUVmax in subchondral bone adjacent to grade 0 cartilage was significantly lower compared to that of grades 1-2 (P < 0.05) and grades 3-4 cartilage (P < 0.001).PET/MRI can simultaneously assess multiple early metabolic and morphologic markers of knee OA across multiple tissues in the joint. Our findings suggest that PET/MR may detect metabolic abnormalities in subchondral bone, which appear normal on MRI.2 J. Magn. Reson. Imaging 2016.

  View details for DOI 10.1002/jmri.25529

  View details for PubMedID 27796082

• Cluster analysis of quantitative MRI T2 and T1? relaxation times of cartilage identifies differences between healthy and ACL-injured individuals at 3T. Osteoarthritis and cartilage Monu, U. D., JORDAN, C. D., Samuelson, B. L., Hargreaves, B. A., Gold, G. E., McWalter, E. J. 2016

  Abstract

  To identify focal lesions of elevated MRI T2 and T1ρ relaxation times in articular cartilage of an ACL-injured group using a novel cluster analysis technique.Eighteen ACL-injured patients underwent 3T MRI T2 and T1ρ relaxometry at baseline, 6 months and 1 year and six healthy volunteers at baseline, 1 day and 1 year. Clusters of contiguous pixels above or below T2 and T1ρ intensity and area thresholds were identified on a projection map of the 3D femoral cartilage surface. The total area of femoral cartilage plate covered by clusters (%CA) was split into areas above (%CA+) and below (%CA-) the thresholds and the differences in %CA(+ or -) over time in the ACL-injured group were determined using the Wilcoxon signed rank test.%CA+ was greater in the ACL-injured patients than the healthy volunteers at 6 months and 1 year with average %CA+ of 5.2 ± 4.0% (p = 0.0054) and 6.6 ± 3.7% (p = 0.0041) for T2 and 6.2 ± 7.1% (p = 0.063) and 8.2 ± 6.9% (p = 0.042) for T1ρ, respectively. %CA- at 6 months and 1 year was 3.0 ± 1.8% (p > 0.1) and 5.9 ± 5.0% (p > 0.1) for T2 and 4.4 ± 4.9% (p > 0.1) and 4.5 ± 4.6% (p > 0.1) for T1ρ, respectively.With the proposed cluster analysis technique, we have quantified cartilage lesion coverage and demonstrated that the ACL-injured group had greater areas of elevated T2 and T1ρ relaxation times as compared to healthy volunteers.

  View details for DOI 10.1016/j.joca.2016.09.015

  View details for PubMedID 27720806

• Interventional dual-energy imaging-Feasibility of rapid kV-switching on a C-arm CT system MEDICAL PHYSICS Mueller, K., Datta, S., Ahmad, M., Choi, J., Moore, T., Pung, L., Niebler, C., Gold, G. E., Maier, A., Fahrig, R. 2016; 43 (10)

  Abstract

  In the last years, dual-energy CT imaging has shown clinical value, thanks to its ability to differentiate materials based on their atomic number and to exploit different properties of images acquired at two different energies. C-arm CT systems are used to guide procedures in the interventional suite. Until now, there are no commercially available systems that employ dual-energy material decomposition. This paper explores the feasibility of implementing a fast kV-switching technique on a clinically available angiographic system for acquiring dual-energy C-arm CT images.As an initial proof of concept, a fast kV-switching approach was implemented on an angiographic C-arm system and the peak tube voltage during 3D rotational scans was measured. The tube voltage measurements during fast kV-switching scans were compared to corresponding measurements on kV-constant scans. Additionally, to prove stability of the requested exposure parameters, the accuracy of the delivered tube current and pulse width were also recorded and compared. In a first phantom experiment, the voxel intensity values of the individual tube voltage components of the fast kV-switching scans were compared to their corresponding kV-constant scans. The same phantom was used for a simple material decomposition between different iodine concentrations and pure water using a fast kV-switching protocol of 81 and 125 kV. In the last experiment, the same kV-switching protocol as in the phantom scan was used in an in vivo pig study to demonstrate the clinical feasibility.During rapid kV-switching acquisitions, the measured tube voltage of the x-ray tube during fast switching scans has an absolute deviation of 0.23 ± 0.13 kV compared to the measured tube voltage produced during kV-constant acquisitions. The stability of the peak tube voltage over different scan requests was about 0.10 kV for the low and 0.46 for the high energy kV-switching scans and less than 0.1 kV for kV-constant scans, indicating slightly lower stability for kV-switching scans. The tube current resulted in a relative deviation of -1.6% for the low and 6.6% overestimation for the high tube voltage of the kV-switching scans compared to the kV-constant scans. The pulse width showed no deviation for the longer pulse width and only minor deviations (0.02 ± 0.02 ms) for the shorter pulse widths compared to the kV-constant scans. The phantom experiment using different iodine concentrations showed an accurate correlation (R(2) > 0.99) between the extracted intensity values in the kV-switching and kV-constant reconstructed volumes, and allows for an automatic differentiation between contrast concentration down to 10% (350 mg/ml iodine) and pure water under low-noise conditions. Preliminary results of iodine and soft tissue separation showed also promising results in the first in vivo pig study.The feasibility of dual-energy imaging using a fast kV-switching method on an angiographic C-arm CT system was investigated. Direct measurements of beam quality in the x-ray field demonstrate the stability of the kV-switching method. Phantom and in vivo experiments showed that images did not deviate from those of corresponding kV-constant scans. All performed experiments confirmed the capability of performing fast kV-switching scans on a clinically available C-arm CT system. More complex material decomposition tasks and postprocessing steps will be part of future investigations.

  View details for DOI 10.1118/1.4962929

  View details for Web of Science ID 000385577900028

  View details for PubMedID 27782692

• Magnetic resonance-guided focused ultrasound treatment of extra-abdominal desmoid tumors: a retrospective multicenter study. European radiology Ghanouni, P., Dobrotwir, A., Bazzocchi, A., Bucknor, M., Bitton, R., Rosenberg, J., Telischak, K., Busacca, M., Ferrari, S., Albisinni, U., Walters, S., Gold, G., Ganjoo, K., Napoli, A., Pauly, K. B., Avedian, R. 2016: -?

  Abstract

  To assess the feasibility, safety and preliminary efficacy of magnetic resonance-guided focused ultrasound (MRgFUS) for the treatment of extra-abdominal desmoid tumours.Fifteen patients with desmoid fibromatosis (six males, nine females; age range, 7-66 years) were treated with MRgFUS, with seven patients requiring multiple treatments (25 total treatments). Changes in viable and total tumour volumes were measured after treatment. Efficacy was evaluated using an exact one-sided Wilcoxon test to determine if the median reduction in viable tumour measured immediately after initial treatment exceeded a threshold of 50 % of the targeted volume. Median decrease after treatment of at least two points in numerical rating scale (NRS) worst and average pain scores was tested with an exact one-sided Wilcoxon test. Adverse events were recorded.After initial MRgFUS treatment, median viable targeted tumour volume decreased 63 %, significantly beyond our efficacy threshold (P = 0.0013). Median viable total tumour volume decreased (105 mL [interquartile range {IQR}, 217 mL] to 54 mL [IQR, 92 mL]) and pain improved (worst scores, 7.5 ± 1.9 vs 2.7 ± 2.6, P = 0.027; average scores, 6 ± 2.3 vs 1.3 ± 2, P = 0.021). Skin burn was the most common complication.MRgFUS significantly and durably reduced viable tumour volume and pain in this series of 15 patients with extra-abdominal desmoid fibromatosis.• Retrospective four-centre study shows MRgFUS safely and effectively treats extra-abdominal desmoid tumours • This non-invasive procedure can eradicate viable tumour in some cases • Alternatively, MRgFUS can provide durable control of tumour growth through repeated treatments • Compared to surgery or radiation, MRgFUS has relatively mild side effects.

  View details for PubMedID 27147222

• Evaluation of an Algorithm to Detect the First Ventilatory Threshold from Heart Rate: 2450 June 3, 10: 30 AM - 10: 45 AM. Medicine and science in sports and exercise Silder, A., Gold, G. E., Bae, S., Ko, B., Jang, D., Delp, S. L. 2016; 48 (5): 672-673

  View details for DOI 10.1249/01.mss.0000487019.84069.12

  View details for PubMedID 27361086

• Is MR-guided High-intensity Focused Ultrasound a Feasible Treatment Modality for Desmoid Tumors? CLINICAL ORTHOPAEDICS AND RELATED RESEARCH Avedian, R. S., Bitton, R., Gold, G., Butts-Pauly, K., Ghanouni, P. 2016; 474 (3): 697-704

  Abstract

  MR-guided high-intensity focused ultrasound is a noninvasive treatment modality that uses focused ultrasound waves to thermally ablate tumors within the human body while minimizing side effects to surrounding healthy tissues. This technology is FDA-approved for certain tumors and has potential to be a noninvasive treatment option for extremity soft tissue tumors. Development of treatment modalities that achieve tumor control, decrease morbidity, or both might be of great benefit for patients. We wanted to assess the potential use of this technology in the treatment of extremity desmoid tumors.(1) Can we use MR-guided high-intensity focused ultrasound to accurately ablate a predetermined target volume within a human cadaver extremity? (2) Does MR-guided high-intensity focused ultrasound treatment stop progression and/or cause regression of extremity desmoid tumors?Simulated tumor volumes in four human cadavers, created by using plastic markers, were ablated using a commercially available focused ultrasound system. Accuracy was determined in accordance with the International Organization of Standards location error by measuring the farthest distance between the ablated tissue and the plane corresponding to the target. Between 2012 and 2014, we treated nine patients with desmoid tumors using focused ultrasound ablation. Indications for this were tumor-related symptoms or failure of conventional treatment. Of those, five of them were available for MRI followup at 12 months or longer (mean, 18.2 months; range, 12-23 months). The radiographic and clinical outcomes of five patients who had desmoid tumors treated with focused ultrasound were prospectively recorded. Patients were assessed preoperatively with MRI and followed at routine intervals after treatment with MRI scans and clinical examination.The ablation accuracy for the four cadaver extremities was 5 mm, 3 mm, 8 mm, and 8 mm. Four patients' tumors became smaller after treatment and one patient has slight progression at the time of last followup. The mean decrease in tumor size determined by MRI measurements was 36% (95% confidence interval, 7%-66%). No patient has received additional adjuvant systemic or local treatment. Treatment-related adverse events included first- and second-degree skin burns occurring in four patients, which were managed successfully without further surgery.This preliminary investigation provides some evidence that MR-guided high-intensity focused ultrasound may be a feasible treatment for desmoid tumors. It may also be of use for other soft tissue neoplasms in situations in which there are limited traditional treatment options such as recurrent sarcomas. Further investigation is necessary to better define the indications, efficacy, role, and long-term oncologic outcomes of focused ultrasound treatment.Level IV, therapeutic study.

  View details for DOI 10.1007/s11999-015-4364-0

  View details for Web of Science ID 000370150000018

  View details for PubMedID 26040967

  View details for PubMedCentralID PMC4746191

• Volumetric multislice gagCEST imaging of articular cartilage: Optimization and comparison with T1rho. Magnetic resonance in medicine Kogan, F., Hargreaves, B. A., Gold, G. E. 2016

  Abstract

  To develop and optimize a multislice glycosaminoglycan (GAG) chemical exchange saturation transfer (GagCEST) sequence for volumetric imaging of articular cartilage, and to validate the sequence against T1ρ relaxation times in whole joint imaging of tibiotalar cartilage.Ex vivo experiments were used to observe the effect of the number of partitions and shot TR on signal-to-noise ratio and measured GagCESTasym . GagCEST imaging of the entire tibiotalar joint was also performed on 10 healthy subjects. The measured GagCESTasym was compared and correlated with T1ρ relaxation times.Ex vivo studies showed a higher average GagCESTasym from articular cartilage on multislice acquisitions acquired with two or more partitions than observed with a single-slice acquisition. In healthy human subjects, an average GagCESTasym of 8.8 ± 0.7% was observed. A coefficient of variation of GagCESTasym across slices of less than 15% was seen for all subjects. Across subjects, a Pearson correlation coefficient of -0.58 was observed between the measured gagCESTasym and T1ρ relaxation times.We demonstrated the feasibility and optimization of multislice GagCEST mapping of articular cartilage. Volumetric analysis and decreased scan times will help to advance the clinical utility of GagCEST imaging of articular cartilage. Magn Reson Med, 2016. © 2016 Wiley Periodicals, Inc.

  View details for DOI 10.1002/mrm.26200

  View details for PubMedID 26923108

• Potential of PET-MRI for imaging of non-oncologic musculoskeletal disease Quantitative Imaging in Medicine and Surgery Kogan, F., Fan, A. P., Gold, G. E. 2016; 6 (6): 756-771

  Abstract

  Early detection of musculoskeletal disease leads to improved therapies and patient outcomes, and would benefit greatly from imaging at the cellular and molecular level. As it becomes clear that assessment of multiple tissues and functional processes are often necessary to study the complex pathogenesis of musculoskeletal disorders, the role of multi-modality molecular imaging becomes increasingly important. New positron emission tomography-magnetic resonance imaging (PET-MRI) systems offer to combine high-resolution MRI with simultaneous molecular information from PET to study the multifaceted processes involved in numerous musculoskeletal disorders. In this article, we aim to outline the potential clinical utility of hybrid PET-MRI to these non-oncologic musculoskeletal diseases. We summarize current applications of PET molecular imaging in osteoarthritis (OA), rheumatoid arthritis (RA), metabolic bone diseases and neuropathic peripheral pain. Advanced MRI approaches that reveal biochemical and functional information offer complementary assessment in soft tissues. Additionally, we discuss technical considerations for hybrid PET-MR imaging including MR attenuation correction, workflow, radiation dose, and quantification.

  View details for DOI 10.21037/qims.2016.12.16

  View details for PubMedCentralID PMC5219958

• Over-exposure Correction in Knee Cone-Beam CT Imaging with Automatic Exposure Control using a Partial Low Dose Scan Choi, J., Muller, K., Hsieh, S., Maier, A., Gold, G., Levenston, M., Fahrig, R., Kontos, D., Flohr, T. G., Lo, J. Y. SPIE-INT SOC OPTICAL ENGINEERING. 2016

  View details for DOI 10.1117/12.2217347

  View details for Web of Science ID 000378352900020

• Upper Limb Strength and Muscle Volume in Healthy Middle-Aged Adults JOURNAL OF APPLIED BIOMECHANICS Saul, K. R., Vidt, M. E., Gold, G. E., Murray, W. M. 2015; 31 (6): 484-491

  Abstract

  Our purpose was to characterize shoulder muscle volume and isometric moment, as well as their relationship, for healthy middle- aged adults. Muscle volume and maximum isometric joint moment were assessed for 6 functional muscle groups of the shoulder, elbow, and wrist in 10 middle-aged adults (46–60 y, 5M, 5F). Compared with young adults, shoulder abductors composed a smaller percentage of total muscle volume (P = .0009) and there was a reduction in shoulder adductor strength relative to elbow flexors (P = .012). We observed a consistent ordering of moment-generating capacity among functional groups across subjects. Although total muscle volume spanned a 2.3-fold range, muscle volume was distributed among functional groups in a consistent manner across subjects. On average, 72% of the variation in joint moment could be explained by the corresponding functional group muscle volume. These data are useful for improved modeling of upper limb musculoskeletal performance in middle-aged subjects, and may improve computational predictions of function for this group.

  View details for DOI 10.1123/jab.2014-0177

  View details for Web of Science ID 000367029400011

  View details for PubMedID 26155870

• The Role of Cartilage Stress in Patellofemoral Pain MEDICINE AND SCIENCE IN SPORTS AND EXERCISE Besier, T. F., Pal, S., Draper, C. E., Fredericson, M., Gold, G. E., Delp, S. L., Beaupre, G. S. 2015; 47 (11): 2416-2422

  Abstract

  Elevated cartilage stress has been identified as a potential mechanism for retropatellar pain; however, there are limited data in the literature to support this mechanism. Females are more likely to develop patellofemoral pain than males, yet the causes of this dimorphism are unclear. We used experimental data and computational modeling to determine whether patients with patellofemoral pain had elevated cartilage stress compared with pain-free controls and test the hypothesis that females exhibit greater cartilage stress than males.We created finite element models of 24 patients with patellofemoral pain (11 males and 13 females) and 16 pain-free controls (8 males and 8 females) to estimate peak patellar cartilage stress (strain energy density) during a stair climb activity. Simulations took into account cartilage morphology from magnetic resonance imaging, joint posture from weight-bearing magnetic resonance imaging, and muscle forces from an EMG-driven model.We found no difference in peak patellar strain energy density between those with patellofemoral pain (1.9 ± 1.23 J·m(-3)) and control subjects (1.66 ± 0.75 J·m(-3), P = 0.52). Females exhibited greater cartilage stress compared with males (2.2 vs 1.3 J·m(-3), respectively; P = 0.0075), with large quadriceps muscle forces (3.7 body weight in females vs 3.3 body weight in males) and 23% smaller joint contact area (females, 467 ± 59 mm2, vs males, 608 ± 95 mm2).Patients with patellofemoral pain did not display significantly greater patellar cartilage stress compared with pain-free controls; however, there was a great deal of subject variation. Females exhibited greater peak cartilage stress compared with males, which might explain the greater prevalence of patellofemoral pain in females compared with that in males, but other mechanical and biological factors are clearly involved in this complex pathway to pain.

  View details for DOI 10.1249/MSS.0000000000000685

  View details for Web of Science ID 000362940900021

  View details for PubMedID 25899103

  View details for PubMedCentralID PMC4609225

• Muscle velocity and inertial force from phase contrast MRI JOURNAL OF MAGNETIC RESONANCE IMAGING Wentland, A. L., McWalter, E. J., Pal, S., Delp, S. L., Gold, G. E. 2015; 42 (2): 526-532

  Abstract

  To evaluate velocity waveforms in muscle and to create a tool and algorithm for computing and analyzing muscle inertial forces derived from 2D phase contrast (PC) magnetic resonance imaging (MRI).PC MRI was performed in the forearm of four healthy volunteers during 1 Hz cycles of wrist flexion-extension as well as in the lower leg of six healthy volunteers during 1 Hz cycles of plantarflexion-dorsiflexion. Inertial forces (F) were derived via the equation F = ma. The mass, m, was derived by multiplying voxel volume by voxel-by-voxel estimates of density via fat-water separation techniques. Acceleration, a, was obtained via the derivative of the PC MRI velocity waveform.Mean velocities in the flexors of the forearm and lower leg were 1.94 ± 0.97 cm/s and 5.57 ± 2.72 cm/s, respectively, as averaged across all subjects; the inertial forces in the flexors of the forearm and lower leg were 1.9 × 10(-3)  ± 1.3 × 10(-3) N and 1.1 × 10(-2)  ± 6.1 × 10(-3) N, respectively, as averaged across all subjects.PC MRI provided a promising means of computing muscle velocities and inertial forces-providing the first method for quantifying inertial forces. J. Magn. Reson. Imaging 2015;42:526-532.

  View details for DOI 10.1002/jmri.24807

  View details for Web of Science ID 000358258600001

  View details for PubMedCentralID PMC4442766

• Approach to MR Imaging of the Elbow and Wrist: Technical Aspects and Innovation. Magnetic resonance imaging clinics of North America Johnson, D., Stevens, K. J., Riley, G., Shapiro, L., Yoshioka, H., Gold, G. E. 2015; 23 (3): 355-366

  Abstract

  Wrist and elbow MR imaging technology is advancing at a dramatic rate. Wrist and elbow MR imaging is performed at medium and higher field strengths with more specialized surface coils and more variable pulse sequences and postprocessing techniques. High field imaging and improved coils lead to an increased signal-to-noise ratio and increased variety of soft tissue contrast options. Three-dimensional imaging is improving in terms of usability and artifacts. Some of these advances have challenges in wrist and elbow imaging, such as postoperative patient imaging, cartilage mapping, and molecular imaging. This review considers technical advances in hardware and software and their clinical applications.

  View details for DOI 10.1016/j.mric.2015.04.008

  View details for PubMedID 26216768

  View details for PubMedCentralID PMC4518502

• Approach to MR Imaging of the Elbow and Wrist: Technical Aspects and Innovation. Magnetic resonance imaging clinics of North America Johnson, D., Stevens, K. J., Riley, G., Shapiro, L., Yoshioka, H., Gold, G. E. 2015; 23 (3): 355-366

  Abstract

  Wrist and elbow MR imaging technology is advancing at a dramatic rate. Wrist and elbow MR imaging is performed at medium and higher field strengths with more specialized surface coils and more variable pulse sequences and postprocessing techniques. High field imaging and improved coils lead to an increased signal-to-noise ratio and increased variety of soft tissue contrast options. Three-dimensional imaging is improving in terms of usability and artifacts. Some of these advances have challenges in wrist and elbow imaging, such as postoperative patient imaging, cartilage mapping, and molecular imaging. This review considers technical advances in hardware and software and their clinical applications.

  View details for DOI 10.1016/j.mric.2015.04.008

  View details for PubMedID 26216768

• Muscle velocity and inertial force from phase contrast MRI. Journal of magnetic resonance imaging Wentland, A. L., McWalter, E. J., Pal, S., Delp, S. L., Gold, G. E. 2015; 42 (2): spcone-?

  Abstract

  To evaluate velocity waveforms in muscle and to create a tool and algorithm for computing and analyzing muscle inertial forces derived from 2D phase contrast (PC) magnetic resonance imaging (MRI).PC MRI was performed in the forearm of four healthy volunteers during 1 Hz cycles of wrist flexion-extension as well as in the lower leg of six healthy volunteers during 1 Hz cycles of plantarflexion-dorsiflexion. Inertial forces (F) were derived via the equation F = ma. The mass, m, was derived by multiplying voxel volume by voxel-by-voxel estimates of density via fat-water separation techniques. Acceleration, a, was obtained via the derivative of the PC MRI velocity waveform.Mean velocities in the flexors of the forearm and lower leg were 1.94 ± 0.97 cm/s and 5.57 ± 2.72 cm/s, respectively, as averaged across all subjects; the inertial forces in the flexors of the forearm and lower leg were 1.9 × 10(-3)  ± 1.3 × 10(-3) N and 1.1 × 10(-2)  ± 6.1 × 10(-3) N, respectively, as averaged across all subjects.PC MRI provided a promising means of computing muscle velocities and inertial forces-providing the first method for quantifying inertial forces. J. Magn. Reson. Imaging 2015;42:526-532.

  View details for DOI 10.1002/jmri.25013

  View details for PubMedID 26192553

• T-2 Relaxation time quantitation differs between pulse sequences in articular cartilage JOURNAL OF MAGNETIC RESONANCE IMAGING Matzat, S. J., McWalter, E. J., Kogan, F., Chen, W., Gold, G. E. 2015; 42 (1): 105-113

  Abstract

  To compare T2 relaxation time measurements between MR pulse sequences at 3 Tesla in agar phantoms and in vivo patellar, femoral, and tibial articular cartilage.T2 relaxation times were quantified in phantoms and knee articular cartilage of eight healthy individuals using a single echo spin echo (SE) as a reference standard and five other pulse sequences: multi-echo SE (MESE), fast SE (2D-FSE), magnetization-prepared spoiled gradient echo (3D-MAPSS), three-dimensional (3D) 3D-FSE with variable refocusing flip angle schedules (3D vfl-FSE), and quantitative double echo steady state (qDESS). Cartilage was manually segmented and average regional T2 relaxation times were obtained for each sequence. A regression analysis was carried out between each sequence and the reference standard, and root-mean-square error (RMSE) was calculated.Phantom measurements from all sequences demonstrated strong fits (R(2)  > 0.8; P < 0.05). For in vivo cartilage measurements, R(2) values, slope, and RMSE were: MESE: 0.25/0.42/5.0 ms, 2D-FSE: 0.64/1.31/9.3 ms, 3D-MAPSS: 0.51/0.66/3.8 ms, 3D vfl-FSE: 0.30/0.414.2 ms, qDESS: 0.60/0.90/4.6 ms.2D-FSE, qDESS, and 3D-MAPSS demonstrated the best fits with SE measurements as well as the greatest dynamic ranges. The 3D-MAPSS, 3D vfl-FSE, and qDESS demonstrated the closest average measurements to SE. Discrepancies in T2 relaxation time quantitation between sequences suggest that care should be taken when comparing results between studies.J. Magn. Reson. Imaging 2014. © 2014 Wiley Periodicals, Inc.

  View details for DOI 10.1002/jmri.24757

  View details for Web of Science ID 000356625500012

  View details for PubMedID 25244647

• OARSI Clinical Trials Recommendations: Hip imaging in clinical trials in osteoarthritis OSTEOARTHRITIS AND CARTILAGE Gold, G. E., Cicuttini, F., Crema, M. D., Eckstein, F., Guermazi, A., Kijowski, R., Link, T. M., Maheu, E., Martel-Pelletier, J., Miller, C. G., Pelletier, J., Peterfy, C. G., Potter, H. G., Roemer, F. W., Hunter, D. J. 2015; 23 (5): 716-731

  Abstract

  Imaging of hip in osteoarthritis (OA) has seen considerable progress in the past decade, with the introduction of new techniques that may be more sensitive to structural disease changes. The purpose of this expert opinion, consensus driven recommendation is to provide detail on how to apply hip imaging in disease modifying clinical trials. It includes information on acquisition methods/techniques (including guidance on positioning for radiography, sequence/protocol recommendations/hardware for magnetic resonance imaging (MRI)); commonly encountered problems (including positioning, hardware and coil failures, artifacts associated with various MRI sequences); quality assurance/control procedures; measurement methods; measurement performance (reliability, responsiveness, and validity); recommendations for trials; and research recommendations.

  View details for DOI 10.1016/j.joca.2015.03.004

  View details for Web of Science ID 000353821200006

  View details for PubMedID 25952344

• OARSI Clinical Trials Recommendations: Hand imaging in clinical trials in osteoarthritis OSTEOARTHRITIS AND CARTILAGE Hunter, D. J., Arden, N., Cicuttini, F., Crema, M. D., Dardzinski, B., Duryea, J., Guermazi, A., Haugen, I. K., Kloppenburg, M., Maheu, E., Miller, C. G., Martel-Pelletier, J., Ochoa-Albiztegui, R. E., Pelletier, J., Peterfy, C., Roemer, F., Gold, G. E. 2015; 23 (5): 732-746

  Abstract

  Tremendous advances have occurred in our understanding of the pathogenesis of hand osteoarthritis (OA) and these are beginning to be applied to trials targeted at modification of the disease course. The purpose of this expert opinion, consensus driven exercise is to provide detail on how one might use and apply hand imaging assessments in disease modifying clinical trials. It includes information on acquisition methods/techniques (including guidance on positioning for radiography, sequence/protocol recommendations/hardware for MRI); commonly encountered problems (including positioning, hardware and coil failures, sequences artifacts); quality assurance/control procedures; measurement methods; measurement performance (reliability, responsiveness, validity); recommendations for trials; and research recommendations.

  View details for DOI 10.1016/j.joca.2015.03.003

  View details for Web of Science ID 000353821200007

  View details for PubMedID 25952345

• OARSI Clinical Trials Recommendations: Knee imaging in clinical trials in osteoarthritis OSTEOARTHRITIS AND CARTILAGE Hunter, D. J., Altman, R. D., Cicuttini, F., Crema, M. D., Duryea, J., Eckstein, F., Guermazi, A., Kijowski, R., Link, T. M., Martel-Pelletier, J., Miller, C. G., Mosher, T. J., Ochoa-Albiztegui, R. E., Pelletier, J., Peterfy, C., Raynauld, J., Roemer, F. W., Totterman, S. M., Gold, G. E. 2015; 23 (5): 698-715

  Abstract

  Significant advances have occurred in our understanding of the pathogenesis of knee osteoarthritis (OA) and some recent trials have demonstrated the potential for modification of the disease course. The purpose of this expert opinion, consensus driven exercise is to provide detail on how one might use and apply knee imaging in knee OA trials. It includes information on acquisition methods/techniques (including guidance on positioning for radiography, sequence/protocol recommendations/hardware for magnetic resonance imaging (MRI)); commonly encountered problems (including positioning, hardware and coil failures, sequences artifacts); quality assurance (QA)/control procedures; measurement methods; measurement performance (reliability, responsiveness, validity); recommendations for trials; and research recommendations.

  View details for DOI 10.1016/j.joca.2015.03.012

  View details for Web of Science ID 000353821200005

  View details for PubMedID 25952343

• T1 rho Dispersion in Articular Cartilage: Relationship to Material Properties and Macromolecular Content CARTILAGE Keenan, K. E., Besier, T. F., Pauly, J. M., Smith, R. L., Delp, S. L., Beaupre, G. S., Gold, G. E. 2015; 6 (2): 113-122

  Abstract

  This study assessed T1ρ relaxation dispersion, measured by magnetic resonance imaging (MRI), as a tool to noninvasively evaluate cartilage material and biochemical properties. The specific objective was to answer two questions: (1) does cartilage initial elastic modulus (E 0) correlate with T1ρ dispersion effects and (2) does collagen or proteoglycan content correlate with T1ρ dispersion effects?Cadaveric patellae with and without visible cartilage damage on conventional MR were included. T2 and T1ρ relaxation times at 500 and 1000 Hz spin-lock field amplitudes were measured. We estimated T1ρ dispersion effects by measuring T1ρ relaxation time at 500 and 1000 Hz and T2 relaxation time and using a new tool, the ratio T1ρ/T2. Cartilage initial elastic modulus, E 0, was measured from initial response of mechanical indentation creep tests. Collagen and proteoglycan contents were measured at the indentation test sites; proteoglycan content was measured by their covalently linked sulfated glycosaminoglycans (sGAG). Pearson correlation coefficients were determined, taking into account the clustering of multiple samples within a single patella specimen.Cartilage initial elastic modulus, E 0, increased with decreasing values of T1ρ/T2 measurements at both 500 Hz (P = 0.034) and 1000 Hz (P = 0.022). 1/T1ρ relaxation time (500 Hz) increased with increasing sGAG content (P = 0.041).T1ρ/T2 ratio, a new tool, and cartilage initial elastic modulus are both measures of water-protein interactions, are dependent on the cartilage structure, and were correlated in this study.

  View details for DOI 10.1177/1947603515569529

  View details for Web of Science ID 000356631400006

  View details for PubMedID 26069714

  View details for PubMedCentralID PMC4462251

• MR Imaging Near Metallic Implants Using MAVRIC SL: Initial Clinical Experience at 3T ACADEMIC RADIOLOGY Gutierrez, L. B., Do, B. H., Gold, G. E., Hargreaves, B. A., Koch, K. M., Worters, P. W., Stevens, K. J. 2015; 22 (3): 370-379

  Abstract

  To compare the effectiveness of multiacquisition with variable resonance image combination selective (MAVRIC SL) with conventional two-dimensional fast spin-echo (2D-FSE) magnetic resonance (MR) techniques at 3T in imaging patients with a variety of metallic implants.Twenty-one 3T MR studies were obtained in 19 patients with different types of metal implants. Paired MAVRIC SL and 2D-FSE sequences were reviewed by two radiologists and compared for in-plane and through-plane metal artifact, visualization of the bone implant interface and surrounding soft tissues, blurring, and overall image quality using a two-tailed Wilcoxon signed rank test. The area of artifact on paired images was measured and compared using a paired Wilcoxon signed rank test. Changes in patient management resulting from MAVRIC SL imaging were documented.Significantly less in-plane and through-plane artifact was seen with MAVRIC SL, with improved visualization of the bone-implant interface and surrounding soft tissues, and superior overall image quality (P = .0001). Increased blurring was seen with MAVRIC SL (P = .0016). MAVRIC SL significantly decreased the image artifact compared to 2D-FSE (P = .0001). Inclusion of MAVRIC SL to the imaging protocol determined the need for surgery or type of surgery in five patients and ruled out the need for surgery in 13 patients. In three patients, the area of interest was well seen on both MAVRIC SL and 2D-FSE images, so the addition of MAVRIC had no effect on patient management.Imaging around metal implants with MAVRIC SL at 3T significantly improved image quality and decreased image artifact compared to conventional 2D-FSE imaging techniques and directly impacted patient management.

  View details for DOI 10.1016/j.acra.2014.09.010

  View details for PubMedID 25435186

• MRI of the Hip for the evaluation of femoroacetabular impingement; past, present, and future. Journal of magnetic resonance imaging : JMRI Riley, G. M., McWalter, E. J., Stevens, K. J., Safran, M. R., Lattanzi, R., Gold, G. E. 2015; 41 (3): 558-572

  Abstract

  The concept of femoroacetabular impingement (FAI) has, in a relatively short time, come to the forefront of orthopedic imaging. In just a few short years MRI findings that were in the past ascribed to degenerative change, normal variation, or other pathologies must now be described and included in radiology reports, as they have been shown, or are suspected to be related to, FAI. Crucial questions have come up in this time, including: what is the relationship of bony morphology to subsequent cartilage and labral damage, and most importantly, how is this morphology related to the development of osteoarthritis? In this review, we attempt to place a historical perspective on the controversy, provide guidelines for interpretation of MRI examinations of patients with suspected FAI, and offer a glimpse into the future of MRI of this complex condition. J. Magn. Reson. Imaging 2014. © 2014 Wiley Periodicals, Inc.

  View details for DOI 10.1002/jmri.24725

  View details for PubMedID 25155435

• Hexagonal Undersampling for Faster MRI Near Metallic Implants MAGNETIC RESONANCE IN MEDICINE Sveinsson, B., Worters, P. W., Gold, G. E., Hargreaves, B. A. 2015; 73 (2): 662-668

  Abstract

  Slice encoding for metal artifact correction acquires a three-dimensional image of each excited slice with view-angle tilting to reduce slice and readout direction artifacts respectively, but requires additional imaging time. The purpose of this study was to provide a technique for faster imaging around metallic implants by undersampling k-space.Assuming that areas of slice distortion are localized, hexagonal sampling can reduce imaging time by 50% compared with conventional scans. This work demonstrates this technique by comparisons of fully sampled images with undersampled images, either from simulations from fully acquired data or from data actually undersampled during acquisition, in patients and phantoms. Hexagonal sampling is also shown to be compatible with parallel imaging and partial Fourier acquisitions. Image quality was evaluated using a structural similarity (SSIM) index.Images acquired with hexagonal undersampling had no visible difference in artifact suppression from fully sampled images. The SSIM index indicated high similarity to fully sampled images in all cases.The study demonstrates the ability to reduce scan time by undersampling without compromising image quality. Magn Reson Med 73:662-668, 2015. © 2014 Wiley Periodicals, Inc.

  View details for DOI 10.1002/mrm.25132

  View details for Web of Science ID 000348139500023

  View details for PubMedID 24549782

  View details for PubMedCentralID PMC4156560

• On high heels and short muscles: a multiscale model for sarcomere loss in the gastrocnemius muscle. Journal of theoretical biology Zöllner, A. M., Pok, J. M., McWalter, E. J., Gold, G. E., Kuhl, E. 2015; 365: 301-310

  Abstract

  High heels are a major source of chronic lower limb pain. Yet, more than one third of all women compromise health for looks and wear high heels on a daily basis. Changing from flat footwear to high heels induces chronic muscle shortening associated with discomfort, fatigue, reduced shock absorption, and increased injury risk. However, the long-term effects of high-heeled footwear on the musculoskeletal kinematics of the lower extremities remain poorly understood. Here we create a multiscale computational model for chronic muscle adaptation to characterize the acute and chronic effects of global muscle shortening on local sarcomere lengths. We perform a case study of a healthy female subject and show that raising the heel by 13cm shortens the gastrocnemius muscle by 5% while the Achilles tendon remains virtually unaffected. Our computational simulation indicates that muscle shortening displays significant regional variations with extreme values of 22% in the central gastrocnemius. Our model suggests that the muscle gradually adjusts to its new functional length by a chronic loss of sarcomeres in series. Sarcomere loss varies significantly across the muscle with an average loss of 9%, virtually no loss at the proximal and distal ends, and a maximum loss of 39% in the central region. These changes reposition the remaining sarcomeres back into their optimal operating regime. Computational modeling of chronic muscle shortening provides a valuable tool to shape our understanding of the underlying mechanisms of muscle adaptation. Our study could open new avenues in orthopedic surgery and enhance treatment for patients with muscle contracture caused by other conditions than high heel wear such as paralysis, muscular atrophy, and muscular dystrophy.

  View details for DOI 10.1016/j.jtbi.2014.10.036

  View details for PubMedID 25451524

  View details for PubMedCentralID PMC4262722

• On high heels and short muscles: A multiscale model for sarcomere loss in the gastrocnemius muscle. Journal of theoretical biology Zöllner, A. M., Pok, J. M., McWalter, E. J., Gold, G. E., Kuhl, E. 2015; 365: 301-310

  View details for DOI 10.1016/j.jtbi.2014.10.036

  View details for PubMedID 25451524

• Simultaneous Whole-Body Time-of-Flight F-18-FDG PET/MRI A Pilot Study Comparing SUVmax With PET/CT and Assessment of MR Image Quality CLINICAL NUCLEAR MEDICINE Iagaru, A., Mittra, E., Minamimoto, R., Jamali, M., Levin, C., Quon, A., Gold, G., Herfkens, R., Vasanawala, S., Gambhir, S. S., Zaharchuk, G. 2015; 14 (1): 1-8

  Abstract

  The recent introduction of hybrid PET/MRI scanners in clinical practice has shown promising initial results for several clinical scenarios. However, the first generation of combined PET/MRI lacks time-of-flight (TOF) technology. Here we report the results of the first patients to be scanned on a completely novel fully integrated PET/MRI scanner with TOF.We analyzed data from patients who underwent a clinically indicated F FDG PET/CT, followed by PET/MRI. Maximum standardized uptake values (SUVmax) were measured from F FDG PET/MRI and F FDG PET/CT for lesions, cerebellum, salivary glands, lungs, aortic arch, liver, spleen, skeletal muscle, and fat. Two experienced radiologists independently reviewed the MR data for image quality.Thirty-six patients (19 men, 17 women, mean [±standard deviation] age of 61 ± 14 years [range: 27-86 years]) with a total of 69 discrete lesions met the inclusion criteria. PET/CT images were acquired at a mean (±standard deviation) of 74 ± 14 minutes (range: 49-100 minutes) after injection of 10 ± 1 mCi (range: 8-12 mCi) of F FDG. PET/MRI scans started at 161 ± 29 minutes (range: 117 - 286 minutes) after the F FDG injection. All lesions identified on PET from PET/CT were also seen on PET from PET/MRI. The mean SUVmax values were higher from PET/MRI than PET/CT for all lesions. No degradation of MR image quality was observed.The data obtained so far using this investigational PET/MR system have shown that the TOF PET system is capable of excellent performance during simultaneous PET/MR with routine pulse sequences. MR imaging was not compromised. Comparison of the PET images from PET/CT and PET/MRI show no loss of image quality for the latter. These results support further investigation of this novel fully integrated TOF PET/MRI instrument.

  View details for Web of Science ID 000346633400023

• Muscle velocity and inertial force from phase contrast MRI. Journal of magnetic resonance imaging : JMRI Wentland, A. L., McWalter, E. J., Pal, S., Delp, S. L., Gold, G. E. 2015; 42 (2): 526–32

  Abstract

  To evaluate velocity waveforms in muscle and to create a tool and algorithm for computing and analyzing muscle inertial forces derived from 2D phase contrast (PC) magnetic resonance imaging (MRI).PC MRI was performed in the forearm of four healthy volunteers during 1 Hz cycles of wrist flexion-extension as well as in the lower leg of six healthy volunteers during 1 Hz cycles of plantarflexion-dorsiflexion. Inertial forces (F) were derived via the equation F = ma. The mass, m, was derived by multiplying voxel volume by voxel-by-voxel estimates of density via fat-water separation techniques. Acceleration, a, was obtained via the derivative of the PC MRI velocity waveform.Mean velocities in the flexors of the forearm and lower leg were 1.94 ± 0.97 cm/s and 5.57 ± 2.72 cm/s, respectively, as averaged across all subjects; the inertial forces in the flexors of the forearm and lower leg were 1.9 × 10(-3)  ± 1.3 × 10(-3) N and 1.1 × 10(-2)  ± 6.1 × 10(-3) N, respectively, as averaged across all subjects.PC MRI provided a promising means of computing muscle velocities and inertial forces-providing the first method for quantifying inertial forces. J. Magn. Reson. Imaging 2015;42:526-532.

  View details for PubMedID 25425185

• Simultaneous whole-body time-of-flight 18F-FDG PET/MRI: a pilot study comparing SUVmax with PET/CT and assessment of MR image quality. Clinical nuclear medicine Iagaru, A., Mittra, E., Minamimoto, R., Jamali, M., Levin, C., Quon, A., Gold, G., Herfkens, R., Vasanawala, S., Gambhir, S. S., Zaharchuk, G. 2015; 40 (1): 1-8

  Abstract

  The recent introduction of hybrid PET/MRI scanners in clinical practice has shown promising initial results for several clinical scenarios. However, the first generation of combined PET/MRI lacks time-of-flight (TOF) technology. Here we report the results of the first patients to be scanned on a completely novel fully integrated PET/MRI scanner with TOF.We analyzed data from patients who underwent a clinically indicated F FDG PET/CT, followed by PET/MRI. Maximum standardized uptake values (SUVmax) were measured from F FDG PET/MRI and F FDG PET/CT for lesions, cerebellum, salivary glands, lungs, aortic arch, liver, spleen, skeletal muscle, and fat. Two experienced radiologists independently reviewed the MR data for image quality.Thirty-six patients (19 men, 17 women, mean [±standard deviation] age of 61 ± 14 years [range: 27-86 years]) with a total of 69 discrete lesions met the inclusion criteria. PET/CT images were acquired at a mean (±standard deviation) of 74 ± 14 minutes (range: 49-100 minutes) after injection of 10 ± 1 mCi (range: 8-12 mCi) of F FDG. PET/MRI scans started at 161 ± 29 minutes (range: 117 - 286 minutes) after the F FDG injection. All lesions identified on PET from PET/CT were also seen on PET from PET/MRI. The mean SUVmax values were higher from PET/MRI than PET/CT for all lesions. No degradation of MR image quality was observed.The data obtained so far using this investigational PET/MR system have shown that the TOF PET system is capable of excellent performance during simultaneous PET/MR with routine pulse sequences. MR imaging was not compromised. Comparison of the PET images from PET/CT and PET/MRI show no loss of image quality for the latter. These results support further investigation of this novel fully integrated TOF PET/MRI instrument.

  View details for DOI 10.1097/RLU.0000000000000611

  View details for PubMedID 25489952

• Metal Artifact Reduction With MAVRIC SL at 3-T MRI in Patients With Hip Arthroplasty AMERICAN JOURNAL OF ROENTGENOLOGY Choi, S., Koch, K. M., Hargreaves, B. A., Stevens, K. J., Gold, G. E. 2015; 204 (1): 140-147

  Abstract

  The objective of our study was to compare the multiacquisition variable-resonance image combination selective (MAVRIC SL) sequence with the 2D fast spin-echo (FSE) sequence for metal artifact reduction on 3-T MRI in patients with hip arthroplasty (HA).Matched 2D FSE and MAVRIC SL images of 21 hips (19 patients with HA) were included in the study group. Paired image sets, composed of 13 coronal and 12 axial slices (total, 25 image sets), of the 21 hips were evaluated. For quantitative analysis, the artifact area was measured at the level of the hip and femur. For qualitative analysis, two musculoskeletal radiologists independently compared paired 2D FSE and MAVRIC SL sets in terms of artifacts, depiction of anatomic detail, level of diagnostic confidence, and detection of abnormal findings.The measured artifact area was significantly smaller (p < 0.05) on MAVRIC SL than 2D FSE at both the level of hip (59.9% reduction with MAVRIC SL) and femur (31.3% reduction with MAVRIC SL). The artifact score was also significantly decreased (p < 0.0001) with MAVRIC SL compared with 2D FSE for both reviewers. The hip joint capsule and the muscle and tendon attachment sites of the obturator externus and iliopsoas muscles were better depicted with MAVRIC SL than 2D FSE (p < 0.0125). Abnormal findings were significantly better shown on MAVRIC SL imaging compared with 2D FSE imaging (p < 0.0001).The MAVRIC SL sequence can significantly reduce metal artifact on 3-T MRI compared with the 2D FSE sequence and can increase diagnostic confidence of 3-T MRI in patients with total HA.

  View details for DOI 10.2214/AJR.13.11785

  View details for Web of Science ID 000348562300044

  View details for PubMedID 25539249

  View details for PubMedCentralID PMC4321802

• Imaging Strategies for Assessing Cartilage Composition in Osteoarthritis CURRENT RHEUMATOLOGY REPORTS Matzat, S. J., Kogan, F., Fong, G. W., Gold, G. E. 2014; 16 (11)

  Abstract

  Efforts to reduce the ever-increasing rates of osteoarthritis (OA) in the developed world require the ability to non-invasively detect the degradation of joint tissues before advanced damage has occurred. This is particularly relevant for damage to articular cartilage because this soft tissue lacks the capacity to repair itself following major damage and is essential to proper joint function. While conventional magnetic resonance imaging (MRI) provides sufficient contrast to visualize articular cartilage morphology, more advanced imaging strategies are necessary for understanding the underlying biochemical composition of cartilage that begins to break down in the earliest stages of OA. This review discusses the biochemical basis and the advantages and disadvantages associated with each of these techniques. Recent implementations for these techniques are touched upon, and future considerations for improving the research and clinical power of these imaging technologies are also discussed.

  View details for DOI 10.1007/s11926-014-0462-3

  View details for Web of Science ID 000343893800009

  View details for PubMedCentralID PMC4322897

• Imaging strategies for assessing cartilage composition in osteoarthritis. Current rheumatology reports Matzat, S. J., Kogan, F., Fong, G. W., Gold, G. E. 2014; 16 (11): 462-?

  Abstract

  Efforts to reduce the ever-increasing rates of osteoarthritis (OA) in the developed world require the ability to non-invasively detect the degradation of joint tissues before advanced damage has occurred. This is particularly relevant for damage to articular cartilage because this soft tissue lacks the capacity to repair itself following major damage and is essential to proper joint function. While conventional magnetic resonance imaging (MRI) provides sufficient contrast to visualize articular cartilage morphology, more advanced imaging strategies are necessary for understanding the underlying biochemical composition of cartilage that begins to break down in the earliest stages of OA. This review discusses the biochemical basis and the advantages and disadvantages associated with each of these techniques. Recent implementations for these techniques are touched upon, and future considerations for improving the research and clinical power of these imaging technologies are also discussed.

  View details for DOI 10.1007/s11926-014-0462-3

  View details for PubMedID 25218737

  View details for PubMedCentralID PMC4322897

• Variability of CubeQuant T-1 rho, quantitative DESS T-2, and cones sodium MRI in knee cartilage OSTEOARTHRITIS AND CARTILAGE Jordan, C. D., McWalter, E. J., Monu, U. D., Watkins, R. D., Chen, W., Bangerter, N. K., Hargreaves, B. A., Gold, G. E. 2014; 22 (10): 1559-1567

  Abstract

  To measure the variability of T1ρ relaxation times using CubeQuant, T2 relaxation times using quantitative double echo in steady state (DESS), and normalized sodium signals using 3D cones sodium magnetic resonance imaging (MRI) of knee cartilage in vivo at 3 T.Eight healthy subjects were scanned at 3 T at baseline, 1 day, 5 months, and 1 year. Ten regions of interest (ROIs) of knee cartilage were segmented in the medial and lateral compartments of each subject's knee. T1ρ and T2 relaxation times and normalized sodium signals were measured and the root-mean-square coefficient of variation (CVRMS) was calculated. Intra-subject variability was measured over short, moderate and long-term, as well as intra-observer and inter-observer variability.The average intra-subject CVRMS measurements over short, moderate, and long-term time periods were 4.6%, 6.1%, and 6.0% for the T1ρ measurements, 6.4%, 9.3%, and 10.7% for the T2 measurements and 11.3%, 11.6%, and 12.9% for the sodium measurements, respectively. The average CVRMS measurements for intra-observer and inter-observer segmentation were 3.8% and 5.7% for the T1ρ measurements, 4.7% and 6.7% for the T2 measurements, and 8.1% and 11.4% for the sodium measurements, respectively.These CVRMS measurements are substantially lower than previously measured changes expected in patients with advanced osteoarthritis compared to healthy volunteers, suggesting that CubeQuant T1ρ, quantitative DESS T2 and 3D cones sodium measurements are sufficiently sensitive for in vivo cartilage studies.

  View details for DOI 10.1016/j.joca.2014.06.001

  View details for Web of Science ID 000343139800027

  View details for PubMedCentralID PMC4185151

• Imaging of cartilage and bone: promises and pitfalls in clinical trials of osteoarthritis. Osteoarthritis and cartilage Eckstein, F., Guermazi, A., Gold, G., Duryea, J., Hellio Le Graverand, M., Wirth, W., Miller, C. G. 2014; 22 (10): 1516-1532

  Abstract

  Imaging in clinical trials is used to evaluate subject eligibility, and/or efficacy of intervention, supporting decision making in drug development by ascertaining treatment effects on joint structure. This review focusses on imaging of bone and cartilage in clinical trials of (knee) osteoarthritis. We narratively review the full-text literature on imaging of bone and cartilage, adding primary experience in the implementation of imaging methods in clinical trials. Aims and constraints of applying imaging in clinical trials are outlined. The specific uses of semi-quantitative and quantitative imaging biomarkers of bone and cartilage in osteoarthritis trials are summarized, focusing on radiography and magnetic resonance imaging (MRI). Studies having compared both imaging methodologies directly and those having established a relationship between imaging biomarkers and clinical outcomes are highlighted. To make this review of practical use, recommendations are provided as to which imaging protocols are ideal for capturing specific aspects of bone and cartilage tissue, and pitfalls in their usage are highlighted. Further, the longitudinal sensitivity to change, of different imaging methods is reported for various patient strata. From these power calculations can be accomplished, provided the strength of the treatment effect is known. In conclusion, current imaging methodologies provide powerful tools for scoring and measuring morphological and compositional aspects of most articular tissues, capturing longitudinal change with reasonable to excellent sensitivity. When employed properly, imaging has tremendous potential for ascertaining treatment effects on various joint structures, potentially over shorter time scales than required for demonstrating effects on clinical outcomes.

  View details for DOI 10.1016/j.joca.2014.06.023

  View details for PubMedID 25278061

• Imaging of cartilage and bone: promises and pitfalls in clinical trials of osteoarthritis OSTEOARTHRITIS AND CARTILAGE Eckstein, F., Guermazi, A., Gold, G., Duryea, J., Le Graverand, M. H., Wirth, W., Miller, C. G. 2014; 22 (10): 1516-1532

  View details for DOI 10.1016/j.joca.2014.06.023

  View details for Web of Science ID 000343139800021

• Quantitative Radiologic Imaging Techniques for Articular Cartilage Composition: Toward Early Diagnosis and Development of Disease-Modifying Therapeutics for Osteoarthritis ARTHRITIS CARE & RESEARCH Oei, E. H., van Tiel, J., Robinson, W. H., Gold, G. E. 2014; 66 (8): 1129-1141

  View details for DOI 10.1002/acr.22316

  View details for PubMedID 24578345

• Optimizing Isotropic Three-Dimensional Fast Spin-Echo Methods for Imaging the Knee JOURNAL OF MAGNETIC RESONANCE IMAGING Li, C. Q., Chen, W., Rosenberg, J. K., Beatty, P. J., Kijowski, R., Hargreaves, B. A., Busse, R. F., Gold, G. E. 2014; 39 (6): 1417-1425

  Abstract

  To optimize acquisition parameters for three dimensional fast spin-echo (3D FSE) imaging of the knee.The knees of eight healthy volunteers were imaged in a 3 Tesla MRI scanner using an eight-channel knee coil. A total of 146 intermediate weighted isotropic resolution 3D FSE (3D-FSE-Cube)images with varied acquisition parameter settings were acquired with an additional reference scan performed for subjective image quality assessment. Images were graded for overall quality, parallel imaging artifact severity and blurring. Cartilage, muscle, and fluid signal-to-noise ratios and fluid-cartilage contrast-to-noise ratios were quantified by acquiring scans without radio frequency excitation and custom-reconstructing the k-space data.Mixed effects regression modeling was used to determine statistically significant effects of different parameters on image quality.Changes in receiver bandwidth, repetition time and echo train length significantly affected all measurements of image quality (P < 0.05). Reducing band width improved all metrics of image quality with the exception of blurring. Reader agreement was slight to fair for subjective metrics, but overall trends in quality ratings were apparent.We used a systematic approach to optimize 3D-FSE-Cube parameters for knee imaging. Image quality was overall improved using a receiver bandwidth of 631.25 kHz, and blurring increased with lower band width and longer echo trains.

  View details for DOI 10.1002/jmri.24315

  View details for Web of Science ID 000335460500010

  View details for PubMedCentralID PMC4083613

• Fiducial marker-based correction for involuntary motion in weight-bearing C-arm CT scanning of knees. II. Experiment. Medical physics Choi, J., Maier, A., Keil, A., Pal, S., McWalter, E. J., Beaupré, G. S., Gold, G. E., Fahrig, R. 2014; 41 (6): 061902-?

  View details for DOI 10.1118/1.4873675

  View details for PubMedID 24877813

• Fiducial marker-based correction for involuntary motion in weight-bearing C-arm CT scanning of knees. II. Experiment. Medical physics Choi, J., Maier, A., Keil, A., Pal, S., McWalter, E. J., Beaupré, G. S., Gold, G. E., Fahrig, R. 2014; 41 (6): 061902-?

  Abstract

  A C-arm CT system has been shown to be capable of scanning a single cadaver leg under loaded conditions by virtue of its highly flexible acquisition trajectories. In Part I of this study, using the 4D XCAT-based numerical simulation, the authors predicted that the involuntary motion in the lower body of subjects in weight-bearing positions would seriously degrade image quality and the authors suggested three motion compensation methods by which the reconstructions could be corrected to provide diagnostic image quality. Here, the authors demonstrate that a flat-panel angiography system is appropriate for scanning both legs of subjects in vivo under weight-bearing conditions and further evaluate the three motion-correction algorithms using in vivo data.The geometry of a C-arm CT system for a horizontal scan trajectory was calibrated using the PDS-2 phantom. The authors acquired images of two healthy volunteers while lying supine on a table, standing, and squatting at several knee flexion angles. In order to identify the involuntary motion of the lower body, nine 1-mm-diameter tantalum fiducial markers were attached around the knee. The static mean marker position in 3D, a reference for motion compensation, was estimated by back-projecting detected markers in multiple projections using calibrated projection matrices and identifying the intersection points in 3D of the back-projected rays. Motion was corrected using three different methods (described in detail previously): (1) 2D projection shifting, (2) 2D deformable projection warping, and (3) 3D rigid body warping. For quantitative image quality analysis, SSIM indices for the three methods were compared using the supine data as a ground truth.A 2D Euclidean distance-based metric of subjects' motion ranged from 0.85 mm (±0.49 mm) to 3.82 mm (±2.91 mm) (corresponding to 2.76 to 12.41 pixels) resulting in severe motion artifacts in 3D reconstructions. Shifting in 2D, 2D warping, and 3D warping improved the SSIM in the central slice by 20.22%, 16.83%, and 25.77% in the data with the largest motion among the five datasets (SCAN5); improvement in off-center slices was 18.94%, 29.14%, and 36.08%, respectively.The authors showed that C-arm CT control can be implemented for nonstandard horizontal trajectories which enabled us to scan and successfully reconstruct both legs of volunteers in weight-bearing positions. As predicted using theoretical models, the proposed motion correction methods improved image quality by reducing motion artifacts in reconstructions; 3D warping performed better than the 2D methods, especially in off-center slices.

  View details for DOI 10.1118/1.4873675

  View details for PubMedID 24877813

  View details for PubMedCentralID PMC4008764

• Mechanisms of osteoarthritis in the knee: MR imaging appearance. Journal of magnetic resonance imaging Shapiro, L. M., McWalter, E. J., Son, M., Levenston, M., Hargreaves, B. A., Gold, G. E. 2014; 39 (6): 1346-1356

  Abstract

  Osteoarthritis has grown to become a widely prevalent disease that has major implications in both individual and public health. Although originally considered to be a degenerative disease driven by "wear and tear" of the articular cartilage, recent evidence has led to a consensus that osteoarthritis pathophysiology should be perceived in the context of the entire joint and multiple tissues. MRI is becoming an increasingly more important modality for imaging osteoarthritis, due to its excellent soft tissue contrast and ability to acquire morphological and biochemical data. This review will describe the pathophysiology of osteoarthritis as it is associated with various tissue types, highlight several promising MR imaging techniques for osteoarthritis and illustrate the expected appearance of osteoarthritis with each technique.

  View details for DOI 10.1002/jmri.24562

  View details for PubMedID 24677706

  View details for PubMedCentralID PMC4016127

• Optimizing isotropic three-dimensional fast spin-echo methods for imaging the knee. Journal of magnetic resonance imaging Li, C. Q., Chen, W., Rosenberg, J. K., Beatty, P. J., Kijowski, R., Hargreaves, B. A., Busse, R. F., Gold, G. E. 2014; 39 (6): 1417-1425

  Abstract

  To optimize acquisition parameters for three dimensional fast spin-echo (3D FSE) imaging of the knee.The knees of eight healthy volunteers were imaged in a 3 Tesla MRI scanner using an eight-channel knee coil. A total of 146 intermediate weighted isotropic resolution 3D FSE (3D-FSE-Cube)images with varied acquisition parameter settings were acquired with an additional reference scan performed for subjective image quality assessment. Images were graded for overall quality, parallel imaging artifact severity and blurring. Cartilage, muscle, and fluid signal-to-noise ratios and fluid-cartilage contrast-to-noise ratios were quantified by acquiring scans without radio frequency excitation and custom-reconstructing the k-space data.Mixed effects regression modeling was used to determine statistically significant effects of different parameters on image quality.Changes in receiver bandwidth, repetition time and echo train length significantly affected all measurements of image quality (P < 0.05). Reducing band width improved all metrics of image quality with the exception of blurring. Reader agreement was slight to fair for subjective metrics, but overall trends in quality ratings were apparent.We used a systematic approach to optimize 3D-FSE-Cube parameters for knee imaging. Image quality was overall improved using a receiver bandwidth of 631.25 kHz, and blurring increased with lower band width and longer echo trains.

  View details for PubMedID 24987753

• FDG uptake in normal tissues and malignant lesions from the first whole-body time-of-flight PET/MRI scanner: Comparison with PET/CT Iagaru, A., Mittra, E., Zaharchuk, G., Frost, R., Elekes, A., Anderson, J., Bobb, C., Lahrman, J., Gold, G., Gambhir, S. SOC NUCLEAR MEDICINE INC. 2014

  View details for Web of Science ID 000361438101156

• MRI detection of forearm soft tissue injuries with radial head fractures. Hand (New York, N.Y.) McGinley, J. C., Gold, G., Cheung, E., Yao, J. 2014; 9 (1): 87-92

  Abstract

  This study aims to evaluate the incidence of forearm soft tissue abnormalities associated with radial head fracture severity based on the Mason classification system.Eighteen patients (age 18-45 years) were prospectively evaluated with elbow radiographs and magnetic resonance imaging (MRI) following longitudinal forearm trauma. MRI was performed within 10 days of the initial injury. Radiographs and MR images were evaluated in a blinded fashion by two musculoskeletal radiologists.Thirteen of 18 patients presented with Mason type I radial head fractures. In all patients with Mason type I fractures, the interosseous membrane (IOM) was intact. Two patients had Mason type II fractures with associated partial and compete tearing of the IOM and three patients had Mason type III fractures with complete tearing of the IOM. Edema was noted in the pronator quadratus in six of 13 type I injuries and seen in all type II and III injuries. No structural forearm soft tissue abnormalities were present in patients with Mason type I injuries. The presence of edema within the pronator quadratus correlated with distal forearm pain.The severity of radial head fracture correlates with longitudinal forearm injury evidenced by the presence of IOM tearing. The findings suggest patients with Mason type II or III fractures of the radial head should undergo further evaluation of the forearm for associated soft tissue injuries. Edema within the pronator quadratus was present following forearm trauma regardless of the severity of fracture and was related to symptomatic forearm pain.

  View details for DOI 10.1007/s11552-013-9561-2

  View details for PubMedID 24570643

• MR imaging of the brachial plexus. Neuroimaging clinics of North America Lutz, A. M., Gold, G., Beaulieu, C. 2014; 24 (1): 91-108

  Abstract

  Continuous improvements in magnetic resonance scanner, coil, and pulse sequence technology have resulted in the ability to perform routine, high-quality imaging of the brachial plexus. With knowledge of the anatomy of the plexus, and a familiarity with common pathologic conditions affecting this area, radiologists can provide valuable imaging evaluation of patients with brachial plexus pathologies.

  View details for DOI 10.1016/j.nic.2013.03.024

  View details for PubMedID 24210315

• MR Imaging of the Brachial Plexus. Neuroimaging clinics of North America Lutz, A. M., Gold, G., Beaulieu, C. 2014; 24 (1): 91-108

  View details for DOI 10.1016/j.nic.2013.03.024

  View details for PubMedID 24210315

• Fat-Suppression Techniques for 3-T MR Imaging of the Musculoskeletal System RADIOGRAPHICS Del Grande, F., Santini, F., Herzka, D. A., Aro, M. R., Dean, C. W., Gold, G. E., Carrino, J. A. 2014; 34 (1): 217-233

  Abstract

  Fat suppression is an important technique in musculoskeletal imaging to improve the visibility of bone-marrow lesions; evaluate fat in soft-tissue masses; optimize the contrast-to-noise ratio in magnetic resonance (MR) arthrography; better define lesions after administration of contrast material; and avoid chemical shift artifacts, primarily at 3-T MR imaging. High-field-strength (eg, 3-T) MR imaging has specific technical characteristics compared with lower-field-strength MR imaging that influence the use and outcome of various fat-suppression techniques. The most commonly used fat-suppression techniques for musculoskeletal 3-T MR imaging include chemical shift (spectral) selective (CHESS) fat saturation, inversion recovery pulse sequences (eg, short inversion time inversion recovery [STIR]), hybrid pulse sequences with spectral and inversion-recovery (eg, spectral adiabatic inversion recovery and spectral attenuated inversion recovery [SPAIR]), spatial-spectral pulse sequences (ie, water excitation), and the Dixon techniques. Understanding the different fat-suppression options allows radiologists to adopt the most appropriate technique for their clinical practice.

  View details for DOI 10.1148/rg.341135130

  View details for Web of Science ID 000329917500022

  View details for PubMedID 24428292

• MORPHOLOGICAL IMAGING OF JOINT REPAIR ADVANCED QUANTITATIVE IMAGING OF KNEE JOINT REPAIR Oei, E. G., Matzat, S. J., Gold, G. E., Regatte, R. R. 2014: 51–108

  View details for Web of Science ID 000344889700003

• A randomized controlled trial on 2 simulation-based training methods in radiology: effects on radiologic technology student skill in assessing image quality. Simulation in healthcare Ahlqvist, J. B., Nilsson, T. A., Hedman, L. R., Desser, T. S., Dev, P., Johansson, M., Youngblood, P. L., Cheng, R. P., Gold, G. E. 2013; 8 (6): 382-387

  Abstract

  A simulator for virtual radiographic examinations was developed. In the virtual environment, the user can perform and analyze radiographic examinations of patient models without the use of ionizing radiation. We investigated if this simulation technique could improve education of radiology technology students. We compared student performance in the assessment of radiographic image quality after training with a conventional manikin or with the virtual radiography simulator.A randomized controlled experimental study involving 31 first-year radiology technology students was performed. It was organized in 4 phases as follows: (I) randomization to control or experimental group based on the results of an anatomy examination; (II) proficiency testing before training; (III) intervention (control group, exposure and analysis of radiographic images of the cervical spine of a manikin; experimental group, exposure and analysis of the cervical spine images in the virtual radiography simulator); and (IV) proficiency testing after training.The experimental group showed significantly higher scores after training compared with those before training (P < 0.01). A linear mixed-effect analysis revealed a significant difference between the control and experimental groups regarding proficiency change (P = 0.01).Virtual radiographic simulation is an effective tool for learning image quality assessment. Simulation can therefore be a valuable adjunct to traditional educational methods and reduce exposure to x-rays and tutoring time.

  View details for DOI 10.1097/SIH.0b013e3182a60a48

  View details for PubMedID 24096919

• Hip-femoral acetabular impingement. Clinics in sports medicine Anderson, C. N., Riley, G. M., Gold, G. E., Safran, M. R. 2013; 32 (3): 409-425

  Abstract

  Magnetic resonance imaging (MRI) has become a valuable technology for the diagnosis and treatment of femoroacetabular impingement (FAI). This article reviews the basic pathophysiology of FAI, as well as the techniques and indications for MRI and magnetic resonance arthrography. Normal MRI anatomy of the hip and pathologic MRI anatomy associated with FAI are also discussed. Several case examples are presented demonstrating the diagnosis and treatment of FAI.

  View details for DOI 10.1016/j.csm.2013.03.010

  View details for PubMedID 23773875

• Hip-femoral acetabular impingement. Clinics in sports medicine Anderson, C. N., Riley, G. M., Gold, G. E., Safran, M. R. 2013; 32 (3): 409-425

  View details for DOI 10.1016/j.csm.2013.03.010

  View details for PubMedID 23773875

• Foot and ankle injuries in sport: imaging correlation with arthroscopic and surgical findings. Clinics in sports medicine Hunt, K. J., Githens, M., Riley, G. M., Kim, M., Gold, G. E. 2013; 32 (3): 525-557

  View details for DOI 10.1016/j.csm.2013.03.007

  View details for PubMedID 23773880

• Foot and ankle injuries in sport: imaging correlation with arthroscopic and surgical findings. Clinics in sports medicine Hunt, K. J., Githens, M., Riley, G. M., Kim, M., Gold, G. E. 2013; 32 (3): 525-557

  Abstract

  Foot and ankle injuries are common in sport. Although many available imaging techniques can be useful in identifying and classifying injuries, magnetic resonance imaging (MRI) provides high levels of sensitivity and specificity for articular and soft-tissue injuries. Arthroscopic and minimally invasive treatment techniques for foot and ankle injuries are rapidly evolving, minimizing morbidity and improving postoperative rehabilitation and return to play. Correlation between MRI and surgical findings can aid in both accessing and treating pathologic processes and structures.

  View details for DOI 10.1016/j.csm.2013.03.007

  View details for PubMedID 23773880

• In vitro analysis of peri-articular soft tissues passive constraining effect on hip kinematics and joint stability. Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA Safran, M. R., Lopomo, N., Zaffagnini, S., Signorelli, C., Vaughn, Z. D., Lindsey, D. P., Gold, G., Giordano, G., Marcacci, M. 2013; 21 (7): 1655-1663

  Abstract

  PURPOSE: Aim of the study is to assess the contribution of peri-articular soft tissues to hip joint kinematics and their influence on hip stability. METHODS: Four hemi-corpse specimens (3 males, average age 72 years) were studied using a custom navigation system. Hip kinematics (femoral head motion relative to the acetabulum and joint range of motion) were evaluated with the hip manually positioned in 36 different positions with (I) soft tissues intact, (II) after removal of the skin and muscles and (III) after partial capsulectomy. Each position was repeated 3 times in each state. RESULTS: Excellent interclass correlation for each test was determined (ICC range, 0.84-0.96). Femoral head anatomical centre displacement relative to the acetabulum occurred in all 3 planes, even with all the soft tissue intact (average, 3.3 ± 2.8 mm lateral translation; 1.4 ± 1.8 mm posterior translation and 0.3 ± 1.5 mm distally). These translations increased as more soft tissue was removed, except medial-lateral displacement, with an average 4.6 ± 2.9 mm lateral translation, 0.7 ± 1.3 mm posterior translation and 1.5 ± 1.9 mm distal translation when partial capsulectomy was performed. Range of motion increased in all 3 planes with increasing removal of the soft tissues. CONCLUSIONS: This study showed that femoral head anatomical centre displacement within the acetabulum occurs and increases with increasing removal of peri-articular soft tissues, confirming their influence on hip stability. Hip kinematics was also influenced by peri-articular soft tissues; specifically range of motion increases with increasing removal of those tissues. From clinicians' point of view, they have therefore to consider the influence of their surgeries on peri-articular soft tissues, since excessive translations may promote hip arthritis.

  View details for DOI 10.1007/s00167-012-2091-6

  View details for PubMedID 22752414

• Regional variation in T1? and T2 times in osteoarthritic human menisci: correlation with mechanical properties and matrix composition. Osteoarthritis and cartilage Son, M., Goodman, S. B., Chen, W., Hargreaves, B. A., Gold, G. E., Levenston, M. E. 2013; 21 (6): 796-805

  Abstract

  Changes in T1ρ and T2 magnetic resonance relaxation times have been associated with articular cartilage degeneration, but similar relationships for meniscal tissue have not been extensively investigated. This work examined relationships between T1ρ and T2 measurements and biochemical and mechanical properties across regions of degenerate human menisci.Average T1ρ and T2 relaxation times were determined for nine regions each of seven medial and 13 lateral menisci from 14 total knee replacement patients. Sulfated glycosaminoglycan (sGAG), collagen and water contents were measured for each region. Biomechanical measurements of equilibrium compressive, dynamic compressive and dynamic shear moduli were made for anterior, central and posterior regions.T1ρ and T2 times showed similar regional patterns, with longer relaxation times in the (radially) middle region compared to the inner and outer regions. Pooled over all regions, T1ρ and T2 times showed strong correlations both with one another and with water content. Correlations with biochemical content varied depending on normalization to wet or dry mass, and both imaging parameters showed stronger correlations with collagen compared to sGAG content. Mechanical properties displayed moderate inverse correlations with increasing T1ρ and T2 times and water content.Both T1ρ and T2 relaxation times correlated strongly with water content and moderately with mechanical properties in osteoarthritic menisci, but not as strongly with sGAG or collagen contents alone. While the ability of magnetic resonance imaging (MRI) to detect early osteoarthritic changes remains the subject of investigation, these results suggest that T1ρ and T2 relaxation times have limited ability to detect compositional variations in degenerate menisci.

  View details for DOI 10.1016/j.joca.2013.03.002

  View details for PubMedID 23499673

• Quantitative MRI techniques of cartilage composition. Quantitative imaging in medicine and surgery Matzat, S. J., van Tiel, J., Gold, G. E., Oei, E. H. 2013; 3 (3): 162-174

  Abstract

  Due to aging populations and increasing rates of obesity in the developed world, the prevalence of osteoarthritis (OA) is continually increasing. Decreasing the societal and patient burden of this disease motivates research in prevention, early detection of OA, and novel treatment strategies against OA. One key facet of this effort is the need to track the degradation of tissues within joints, especially cartilage. Currently, conventional imaging techniques provide accurate means to detect morphological deterioration of cartilage in the later stages of OA, but these methods are not sensitive to the subtle biochemical changes during early disease stages. Novel quantitative techniques with magnetic resonance imaging (MRI) provide direct and indirect assessments of cartilage composition, and thus allow for earlier detection and tracking of OA. This review describes the most prominent quantitative MRI techniques to date-dGEMRIC, T2 mapping, T1rho mapping, and sodium imaging. Other, less-validated methods for quantifying cartilage composition are also described-Ultrashort echo time (UTE), gagCEST, and diffusion-weighted imaging (DWI). For each technique, this article discusses the proposed biochemical correlates, as well its advantages and limitations for clinical and research use. The article concludes with a detailed discussion of how the field of quantitative MRI has progressed to provide information regarding two specific patient populations through clinical research-patients with anterior cruciate ligament rupture and patients with impingement in the hip. While quantitative imaging techniques continue to rapidly evolve, specific challenges for each technique as well as challenges to clinical applications remain.

  View details for DOI 10.3978/j.issn.2223-4292.2013.06.04

  View details for PubMedID 23833729

  View details for PubMedCentralID PMC3701096

• Application of advanced magnetic resonance imaging techniques in evaluation of the lower extremity. Radiologic clinics of North America Braun, H. J., Dragoo, J. L., Hargreaves, B. A., Levenston, M. E., Gold, G. E. 2013; 51 (3): 529-545

  Abstract

  This article reviews current magnetic resonance imaging (MR imaging) techniques for imaging the lower extremity, focusing on imaging of the knee, ankle, and hip joints. Recent advancements in MR imaging include imaging at 7 T, using multiple receiver channels, T2* imaging, and metal suppression techniques, allowing more detailed visualization of complex anatomy, evaluation of morphologic changes within articular cartilage, and imaging around orthopedic hardware.

  View details for DOI 10.1016/j.rcl.2012.12.001

  View details for PubMedID 23622097

  View details for PubMedCentralID PMC3639445

• Application of advanced magnetic resonance imaging techniques in evaluation of the lower extremity. Radiologic clinics of North America Braun, H. J., Dragoo, J. L., Hargreaves, B. A., Levenston, M. E., Gold, G. E. 2013; 51 (3): 529-545

  View details for DOI 10.1016/j.rcl.2012.12.001

  View details for PubMedID 23622097

• Musculoskeletal MRI at 3.0 T and 7.0 T: A comparison of relaxation times and image contrast EUROPEAN JOURNAL OF RADIOLOGY Jordan, C. D., Saranathan, M., Bangerter, N. K., Hargreaves, B. A., Gold, G. E. 2013; 82 (5): 734-739

  Abstract

  The purpose of this study was to measure and compare the relaxation times of musculoskeletal tissues at 3.0 T and 7.0 T, and to use these measurements to select appropriate parameters for musculoskeletal protocols at 7.0 T.We measured the T₁ and T₂ relaxation times of cartilage, muscle, synovial fluid, bone marrow and subcutaneous fat at both 3.0 T and 7.0 T in the knees of five healthy volunteers. The T₁ relaxation times were measured using a spin-echo inversion recovery sequence with six inversion times. The T₂ relaxation times were measured using a spin-echo sequence with seven echo times. The accuracy of both the T₁ and T₂ measurement techniques was verified in phantoms at both magnetic field strengths. We used the measured relaxation times to help design 7.0 T musculoskeletal protocols that preserve the favorable contrast characteristics of our 3.0 T protocols, while achieving significantly higher resolution at higher SNR efficiency.The T₁ relaxation times in all tissues at 7.0 T were consistently higher than those measured at 3.0 T, while the T₂ relaxation times at 7.0 T were consistently lower than those measured at 3.0 T. The measured relaxation times were used to help develop high resolution 7.0 T protocols that had similar fluid-to-cartilage contrast to that of the standard clinical 3.0 T protocols for the following sequences: proton-density-weighted fast spin-echo (FSE), T₂-weighted FSE, and 3D-FSE-Cube.The T₁ and T₂ changes were within the expected ranges. Parameters for musculoskeletal protocols at 7.0 T can be optimized based on these values, yielding improved resolution in musculoskeletal imaging with similar contrast to that of standard 3.0 T clinical protocols.

  View details for DOI 10.1016/j.ejrad.2011.09.021

  View details for Web of Science ID 000317335800012

  View details for PubMedID 22172536

  View details for PubMedCentralID PMC3310288

• Patellar maltracking is prevalent among patellofemoral pain subjects with patella alta: An upright, weightbearing MRI study JOURNAL OF ORTHOPAEDIC RESEARCH Pal, S., Besier, T. F., Beaupre, G. S., Fredericson, M., Delp, S. L., Gold, G. E. 2013; 31 (3): 448-457

  Abstract

  The purpose of this study is to determine if patellar maltracking is more prevalent among patellofemoral (PF) pain subjects with patella alta compared to subjects with normal patella height. We imaged 37 PF pain and 15 pain free subjects in an open-configuration magnetic resonance imaging scanner while they stood in a weightbearing posture. We measured patella height using the Caton-Deschamps, Blackburne-Peel, Insall-Salvati, Modified Insall-Salvati, and Patellotrochlear indices, and classified the subjects into patella alta and normal patella height groups. We measured patella tilt and bisect offset from oblique-axial plane images, and classified the subjects into maltracking and normal tracking groups. Patellar maltracking was more prevalent among PF pain subjects with patella alta compared to PF pain subjects with normal patella height (two-tailed Fisher's exact test, p<0.050). Using the Caton-Deschamps index, 67% (8/12) of PF pain subjects with patella alta were maltrackers, whereas only 16% (4/25) of PF pain subjects with normal patella height were maltrackers. Patellofemoral pain subjects classified as maltrackers displayed a greater patella height compared to the pain free and PF pain subjects classified as normal trackers (two-tailed unpaired t-tests with Bonferroni correction, p<0.017). This study adds to our understanding of PF pain in two ways-(1) we demonstrate that patellar maltracking is more prevalent in PF pain subjects with patella alta compared to subjects with normal patella height; and (2) we show greater patella height in PF pain subjects compared to pain free subjects using four indices commonly used in clinics.

  View details for DOI 10.1002/jor.22256

  View details for Web of Science ID 000313980600016

  View details for PubMedID 23165335

  View details for PubMedCentralID PMC3562698

• Human cartilage repair with a photoreactive adhesive-hydrogel composite. Science translational medicine Sharma, B., Fermanian, S., Gibson, M., Unterman, S., Herzka, D. A., Cascio, B., Coburn, J., Hui, A. Y., Marcus, N., Gold, G. E., Elisseeff, J. H. 2013; 5 (167): 167ra6-?

  Abstract

  Surgical options for cartilage resurfacing may be significantly improved by advances and application of biomaterials that direct tissue repair. A poly(ethylene glycol) diacrylate (PEGDA) hydrogel was designed to support cartilage matrix production, with easy surgical application. A model in vitro system demonstrated deposition of cartilage-specific extracellular matrix in the hydrogel biomaterial and stimulation of adjacent cartilage tissue development by mesenchymal stem cells. For translation to the joint environment, a chondroitin sulfate adhesive was applied to covalently bond and adhere the hydrogel to cartilage and bone tissue in articular defects. After preclinical testing in a caprine model, a pilot clinical study was initiated where the biomaterials system was combined with standard microfracture surgery in 15 patients with focal cartilage defects on the medial femoral condyle. Control patients were treated with microfracture alone. Magnetic resonance imaging showed that treated patients achieved significantly higher levels of tissue fill compared to controls. Magnetic resonance spin-spin relaxation times (T(2)) showed decreasing water content and increased tissue organization over time. Treated patients had less pain compared with controls, whereas knee function [International Knee Documentation Committee (IKDC)] scores increased to similar levels between the groups over the 6 months evaluated. No major adverse events were observed over the study period. With further clinical testing, this practical biomaterials strategy has the potential to improve the treatment of articular cartilage defects.

  View details for DOI 10.1126/scitranslmed.3004838

  View details for PubMedID 23303605

• Human Cartilage Repair with a Photoreactive Adhesive-Hydrogel Composite SCIENCE TRANSLATIONAL MEDICINE Sharma, B., Fermanian, S., Gibson, M., Unterman, S., Herzka, D. A., Cascio, B., Coburn, J., Hui, A. Y., Marcus, N., Gold, G. E., Elisseeff, J. H. 2013; 5 (167)

  Abstract

  Surgical options for cartilage resurfacing may be significantly improved by advances and application of biomaterials that direct tissue repair. A poly(ethylene glycol) diacrylate (PEGDA) hydrogel was designed to support cartilage matrix production, with easy surgical application. A model in vitro system demonstrated deposition of cartilage-specific extracellular matrix in the hydrogel biomaterial and stimulation of adjacent cartilage tissue development by mesenchymal stem cells. For translation to the joint environment, a chondroitin sulfate adhesive was applied to covalently bond and adhere the hydrogel to cartilage and bone tissue in articular defects. After preclinical testing in a caprine model, a pilot clinical study was initiated where the biomaterials system was combined with standard microfracture surgery in 15 patients with focal cartilage defects on the medial femoral condyle. Control patients were treated with microfracture alone. Magnetic resonance imaging showed that treated patients achieved significantly higher levels of tissue fill compared to controls. Magnetic resonance spin-spin relaxation times (T(2)) showed decreasing water content and increased tissue organization over time. Treated patients had less pain compared with controls, whereas knee function [International Knee Documentation Committee (IKDC)] scores increased to similar levels between the groups over the 6 months evaluated. No major adverse events were observed over the study period. With further clinical testing, this practical biomaterials strategy has the potential to improve the treatment of articular cartilage defects.

  View details for DOI 10.1126/scitranslmed.3004838

  View details for Web of Science ID 000313568200004

  View details for PubMedID 23303605

• T1-weighted sodium MRI of the articulator cartilage in osteoarthritis: a cross sectional and longitudinal study. PloS one Newbould, R. D., Miller, S. R., Upadhyay, N., Rao, A. W., Swann, P., Gold, G. E., Strachan, R. K., Matthews, P. M., Taylor, P. C., Brown, A. P. 2013; 8 (8)

  Abstract

  Structural magnetic resonance imaging (MRI) has shown great utility in diagnosing soft tissue burden in osteoarthritis (OA), though MRI measures of cartilage integrity have proven more elusive. Sodium MRI can reflect the proteoglycan content of cartilage; however, it requires specialized hardware, acquisition sequences, and long imaging times. This study was designed to assess the potential of a clinically feasible sodium MRI acquisition to detect differences in the knee cartilage of subjects with OA versus healthy controls (HC), and to determine whether longitudinal changes in sodium content are observed at 3 and 6 months. 28 subjects with primary knee OA and 19 HC subjects age and gender matched were enrolled in this ethically-approved study. At baseline, 3 and 6 months subjects underwent structural MRI and a 0.4ms echo time 3D T1-weighted sodium scan as well as the knee injury and osteoarthritis outcome score (KOOS) and knee pain by visual analogue score (VAS). A standing radiograph of the knee was taken for Kellgren-Lawrence (K-L) scoring. A blinded reader outlined the cartilage on the structural images which was used to determine median T1-weighted sodium concentrations in each region of interest on the co-registered sodium scans. VAS, K-L, and KOOS all significantly separated the OA and HC groups. OA subjects had higher T1-weighted sodium concentrations, most strongly observed in the lateral tibial, lateral femoral and medial patella ROIs. There were no significant changes in cartilage volume or sodium concentration over 6 months. This study has shown that a clinically-feasible sodium MRI at a moderate 3T field strength and imaging time with fluid attenuation by T1 weighting significantly separated HCs from OA subjects.

  View details for DOI 10.1371/journal.pone.0073067

  View details for PubMedID 23940822

  View details for PubMedCentralID PMC3733834

• Analysis of Three-dimensional Joint Space of the Tibiofemoral Joint 60th IEEE Nuclear Science Symposium (NSS) / Medical Imaging Conference (MIC) / 20th International Workshop on Room-Temperature Semiconductor X-ray and Gamma-ray Detectors Choi, J., McWalter, E. J., Pal, S., Maier, A., Gold, G. E., Fahrig, R. IEEE. 2013

  View details for Web of Science ID 000347163500032

• Comparison of MRI and 18F-NaF PET/CT in patients with patellofemoral pain JOURNAL OF MAGNETIC RESONANCE IMAGING Draper, C. E., Quon, A., Fredericson, M., Besier, T. F., Delp, S. L., Beaupre, G. S., Gold, G. E. 2012; 36 (4): 928-932

  Abstract

  To determine whether bone metabolic activity corresponds to bone and cartilage damage in patients with patellofemoral pain.We acquired magnetic resonance imaging (MRI) and (18) F-NaF positron emission tomography (PET) / computed tomography (CT) scans of the knees of 22 subjects. We compared locations of increased tracer uptake on the (18) F-NaF PET images to bone marrow edema and cartilage damage visualized on MRI.We found that increased bone activity on (18) F-NaF PET does not always correspond to structural damage in the bone or cartilage as seen on MRI.Our results suggest that (18) F-NaF PET/CT may provide additional information in patellofemoral pain patients compared to MRI.

  View details for DOI 10.1002/jmri.23682

  View details for Web of Science ID 000308884300018

  View details for PubMedID 22549985

  View details for PubMedCentralID PMC3411864

• Advances in musculoskeletal MRI: Technical considerations JOURNAL OF MAGNETIC RESONANCE IMAGING Shapiro, L., Harish, M., Hargreaves, B., Staroswiecki, E., Gold, G. 2012; 36 (4): 775-787

  Abstract

  The technology of musculoskeletal magnetic resonance imaging (MRI) is advancing at a dramatic rate. MRI is now done at medium and higher field strengths with more specialized surface coils and with more variable pulse sequences and postprocessing techniques than ever before. These innumerable technical advances are advantageous as they lead to an increased signal-to-noise ratio and increased variety of soft-tissue contrast options. However, at the same time they potentially produce more imaging artifacts when compared with past techniques. Substantial technical advances have considerable clinical challenges in musculoskeletal radiology such as postoperative patient imaging, cartilage mapping, and molecular imaging. In this review we consider technical advances in hardware and software of musculoskeletal MRI along with their clinical applications.

  View details for DOI 10.1002/jmri.23629

  View details for Web of Science ID 000308884300002

  View details for PubMedID 22987756

  View details for PubMedCentralID PMC3448292

• Diagnosis of osteoarthritis: Imaging BONE Braun, H. J., Gold, G. E. 2012; 51 (2): 278-288

  Abstract

  Osteoarthritis (OA) is a chronic, debilitating joint disease characterized by degenerative changes to the bones, cartilage, menisci, ligaments, and synovial tissue. Imaging modalities such as radiography, magnetic resonance imaging (MRI), optical coherence tomography (OCT), and ultrasound (US) permit visualization of these structures and can evaluate disease onset and progression. Radiography is primarily useful for the assessment of bony structures, while OCT is used for evaluation of articular cartilage and US for ligaments and the synovium. MRI permits visualization of all intraarticular structures and pathologies, though US or OCT may be preferential in some circumstances. As OA is a disease of the whole joint, a combination of imaging techniques may be necessary in order to gain the most comprehensive picture of the disease state. This article is part of a Special Issue entitled "Osteoarthritis".

  View details for DOI 10.1016/j.bone.2011.11.019

  View details for Web of Science ID 000305545600013

  View details for PubMedID 22155587

  View details for PubMedCentralID PMC3306456

• Patellar tilt correlates with vastus lateralis: Vastus medialis activation ratio in maltracking patellofemoral pain patients JOURNAL OF ORTHOPAEDIC RESEARCH Pal, S., Besier, T. F., Draper, C. E., Fredericson, M., Gold, G. E., Beaupre, G. S., Delp, S. L. 2012; 30 (6): 927-933

  Abstract

  Patellofemoral (PF) pain is a common ailment of the lower extremity. A theorized cause for pain is patellar maltracking due to vasti muscle activation imbalance, represented as large vastus lateralis:vastus medialis (VL:VM) activation ratios. However, evidence relating vasti muscle activation imbalance to patellar maltracking is limited. The purpose of this study was to investigate the relationship between VL:VM activation ratio and patellar tracking measures, patellar tilt and bisect offset, in PF pain subjects and pain-free controls. We evaluated VL:VM activation ratio and VM activation delay relative to VL activation in 39 PF pain subjects and 15 pain-free controls during walking. We classified the PF pain subjects into normal tracking and maltracking groups based on patellar tilt and bisect offset measured from weight-bearing magnetic resonance imaging. Patellar tilt correlated with VL:VM activation ratio only in PF pain subjects classified as maltrackers. This suggests that a clinical intervention targeting vasti muscle activation imbalance may be effective only in PF pain subjects classified as maltrackers.

  View details for DOI 10.1002/jor.22008

  View details for Web of Science ID 000302466700012

  View details for PubMedID 22086708

  View details for PubMedCentralID PMC3303943

• UTE T2* mapping detects sub-clinical meniscus degeneration OSTEOARTHRITIS AND CARTILAGE McWalter, E. J., Gold, G. E. 2012; 20 (6): 471-472

  View details for DOI 10.1016/j.joca.2012.02.640

  View details for Web of Science ID 000304733900002

  View details for PubMedID 22406647

• T2* measurement of the knee articular cartilage in osteoarthritis at 3T JOURNAL OF MAGNETIC RESONANCE IMAGING Newbould, R. D., Miller, S. R., Toms, L. D., Swann, P., Tielbeek, J. A., Gold, G. E., Strachan, R. K., Taylor, P. C., Matthews, P. M., Brown, A. P. 2012; 35 (6): 1422-1429

  Abstract

  To measure reproducibility, longitudinal and cross-sectional differences in T2* maps at 3 Tesla (T) in the articular cartilage of the knee in subjects with osteoarthritis (OA) and healthy matched controls.MRI data and standing radiographs were acquired from 33 subjects with OA and 21 healthy controls matched for age and gender. Reproducibility was determined by two sessions in the same day, while longitudinal and cross-sectional group differences used visits at baseline, 3 and 6 months. Each visit contained symptomological assessments and an MRI session consisting of high resolution three-dimensional double-echo-steady-state (DESS) and co-registered T2* maps of the most diseased knee. A blinded reader delineated the articular cartilage on the DESS images and median T2* values were reported.T2* values showed an intra-visit reproducibility of 2.0% over the whole cartilage. No longitudinal effects were measured in either group over 6 months. T2* maps revealed a 5.8% longer T2* in the medial tibial cartilage and 7.6% and 6.5% shorter T2* in the patellar and lateral tibial cartilage, respectively, in OA subjects versus controls (P < 0.02).T2* mapping is a repeatable process that showed differences between the OA subject and control groups.

  View details for DOI 10.1002/jmri.23598

  View details for Web of Science ID 000304035100020

  View details for PubMedID 22314961

• Simultaneous Estimation of T-2 and Apparent Diffusion Coefficient in Human Articular Cartilage In Vivo with a Modified Three-Dimensional Double Echo Steady State (DESS) Sequence at 3 T MAGNETIC RESONANCE IN MEDICINE Staroswiecki, E., Granlund, K. L., Alley, M. T., Gold, G. E., Hargreaves, B. A. 2012; 67 (4): 1086-1096

  Abstract

  T(2) mapping and diffusion-weighted imaging complement morphological imaging for assessing cartilage disease and injury. The double echo steady state sequence has been used for morphological imaging and generates two echoes with markedly different T(2) and diffusion weighting. Modifying the spoiler gradient area and flip angle of the double echo steady state sequence allows greater control of the diffusion weighting of both echoes. Data from two acquisitions with different spoiler gradient areas and flip angles are used to simultaneously estimate the T(2) and apparent diffusion coefficient of each voxel. This method is verified in phantoms and validated in vivo in the knee; estimates from different regions of interest in the phantoms and cartilage are compared to those obtained using standard spin-echo methods. The Pearson correlations were 0.984 for T(2) (∼2% relative difference between spin-echo and double echo steady state estimates) and 0.997 for apparent diffusion coefficient (˜1% relative difference between spin-echo and double echo steady state estimates) for the phantom study and 0.989 for T(2) and 0.987 for apparent diffusion coefficient in regions of interest in the human knee in vivo. High accuracy for simultaneous three-dimensional T(2) and apparent diffusion coefficient measurements are demonstrated, while also providing morphologic three-dimensional images without blurring or distortion in reasonable scan times.

  View details for DOI 10.1002/mrm.23090

  View details for Web of Science ID 000301533500022

  View details for PubMedID 22179942

  View details for PubMedCentralID PMC3306505

• Simultaneous Fat Suppression and Band Reduction with Large-Angle Multiple-Acquisition Balanced Steady-State Free Precession MAGNETIC RESONANCE IN MEDICINE Quist, B., Hargreaves, B. A., Cukur, T., Morrell, G. R., Gold, G. E., Bangerter, N. K. 2012; 67 (4): 1004-1012

  Abstract

  Balanced steady-state free precession (bSSFP) MRI is a rapid and signal-to-noise ratio-efficient imaging method, but suffers from characteristic bands of signal loss in regions of large field inhomogeneity. Several methods have been developed to reduce the severity of these banding artifacts, typically involving the acquisition of multiple bSSFP datasets (and the accompanying increase in scan time). Fat suppression with bSSFP is also challenging; most existing methods require an additional increase in scan time, and some are incompatible with bSSFP band-reduction techniques. This work was motivated by the need for both robust fat suppression and band reduction in the presence of field inhomogeneity when using bSSFP for flow-independent peripheral angiography. The large flip angles used in this application to improve vessel conspicuity and contrast lead to specific absorption rate considerations, longer repetition times, and increased severity of banding artifacts. In this work, a novel method that simultaneously suppresses fat and reduces bSSFP banding artifact with the acquisition of only two phase-cycled bSSFP datasets is presented. A weighted sum of the two bSSFP acquisitions is taken on a voxel-by-voxel basis, effectively synthesizing an off-resonance profile at each voxel that puts fat in the stop band while keeping water in the pass band. The technique exploits the near-sinusoidal shape of the bSSFP off-resonance spectrum for many tissues at large (>50°) flip angles.

  View details for DOI 10.1002/mrm.23076

  View details for Web of Science ID 000301533500014

  View details for PubMedID 22038883

  View details for PubMedCentralID PMC3306491

• Oral manganese as an MRI contrast agent for the detection of nociceptive activity NMR IN BIOMEDICINE Jacobs, K. E., Behera, D., Rosenberg, J., Gold, G., Moseley, M., Yeomans, D., Biswal, S. 2012; 25 (4): 563-569

  Abstract

  The ability of divalent manganese to enter neurons via calcium channels makes manganese an excellent MRI contrast agent for the imaging of nociception, the afferent neuronal encoding of pain perception. There is growing evidence that nociceptive neurons possess increased expression and activity of calcium channels, which would allow for the selective accumulation of manganese at these sites. In this study, we show that oral manganese chloride leads to increased enhancement of peripheral nerves involved in nociception on T(1)-weighted MRI. Oral rather than intravenous administration was chosen for its potentially better safety profile, making it a better candidate for clinical translation with important applications, such as pain diagnosis, therapy and research. The spared nerve injury (SNI) model of neuropathic pain was used for the purposes of this study. SNI rats were given, sequentially, increasing amounts of manganese chloride (lowest, 2.29 mg/100 g weight; highest, 20.6 mg/100 g weight) with alanine and vitamin D(3) by oral gavage. Compared with controls, SNI rats demonstrated increased signal-to-background ratios on T(1)-weighted fast spin echo MRI, which was confirmed by and correlated strongly with spectrometry measurements of nerve manganese concentration. We also found the difference between SNI and control rats to be greater at 48 h than at 24 h after dosing, indicating increased manganese retention in addition to increased manganese uptake in nociceptive nerves. This study demonstrates that oral manganese is a viable method for the imaging of nerves associated with increased nociceptive activity.

  View details for DOI 10.1002/nbm.1773

  View details for Web of Science ID 000302015500011

  View details for PubMedID 22447731

• Patients with patellofemoral pain exhibit elevated bone metabolic activity at the patellofemoral joint JOURNAL OF ORTHOPAEDIC RESEARCH Draper, C. E., Fredericson, M., Gold, G. E., Besier, T. F., Delp, S. L., Beaupre, G. S., Quon, A. 2012; 30 (2): 209-213

  Abstract

  Patellofemoral pain is characterized by pain behind the kneecap and is often thought to be due to high stress at the patellofemoral joint. While we cannot measure bone stress in vivo, we can visualize bone metabolic activity using (18) F NaF PET/CT, which may be related to bone stress. Our goals were to use (18) F NaF PET/CT to evaluate whether subjects with patellofemoral pain exhibit elevated bone metabolic activity and to determine whether bone metabolic activity correlates with pain intensity. We examined 20 subjects diagnosed with patellofemoral pain. All subjects received an (18) F NaF PET/CT scan of their knees. Uptake of (18) F NaF in the patella and trochlea was quantified by computing the standardized uptake value and normalizing by the background tracer uptake in bone. We detected increased tracer uptake in 85% of the painful knees examined. We found that the painful knees exhibited increased tracer uptake compared to the pain-free knees of four subjects with unilateral pain (P = 0.0006). We also found a correlation between increasing tracer uptake and increasing pain intensity (r(2)  = 0.55; P = 0.0005). The implication of these results is that patellofemoral pain may be related to bone metabolic activity at the patellofemoral joint.

  View details for DOI 10.1002/jor.21523

  View details for Web of Science ID 000298581200007

  View details for PubMedID 21812024

  View details for PubMedCentralID PMC3219799

• MRI of weight bearing and movement OSTEOARTHRITIS AND CARTILAGE Shapiro, L. M., Gold, G. E. 2012; 20 (2): 69-78

  Abstract

  Conventional, static magnetic resonance imaging (MRI) is able to provide a vast amount of information regarding the anatomy and pathology of the musculoskeletal system. However, patients, especially those whose pain is position dependent or elucidated by movement, may benefit from more advanced imaging techniques that allow for the acquisition of functional information. This manuscript reviews a variety of advancements in MRI techniques that are used to image the musculoskeletal system dynamically, while in motion or under load. The methodologies, advantages and drawbacks of stress MRI, cine-phase contrast MRI and real-time MRI are discussed as each has helped to advance the field by providing a scientific basis for understanding normal and pathological musculoskeletal anatomy and function. Advancements in dynamic MR imaging will certainly lead to improvements in the understanding, prevention, diagnosis and treatment of musculoskeletal disorders. It is difficult to anticipate that dynamic MRI will replace conventional MRI, however, dynamic MRI may provide additional valuable information to findings of conventional MRI.

  View details for DOI 10.1016/j.joca.2011.11.003

  View details for Web of Science ID 000300124400001

  View details for PubMedID 22138286

• Reproducibility of sodium MRI measures of articular cartilage of the knee in osteoarthritis OSTEOARTHRITIS AND CARTILAGE Newbould, R. D., Miller, S. R., Tielbeek, J. A., Toms, L. D., Rao, A. W., Gold, G. E., STRACHAN, R. K., Taylor, P. C., Matthews, P. M., Brown, A. P. 2012; 20 (1): 29-35

  Abstract

  To determine the stability and reproducibility of the sodium magnetic resonance imaging (MRI) signal measured in the articular cartilage of the knee in both healthy volunteers and osteoarthritis (OA) patients.This was a prospective Research Ethics Committee approved study that acquired sodium and proton MRI data from 15 subjects with OA (three males, age 64 ± 10) and five healthy controls age and sex matched over the group. Each subject underwent standing planar radiographs of their knees for radiological scoring as well as symptomatological assessment questionnaires. In two MRI sessions on the same day, high resolution double-echo steady state (DESS) and 3D short echo time sodium MRI images of the most diseased knee were acquired and co-registered in each session. A blinded reader (LT) manually delineated the articular cartilage into four discrete regions, and two combined regions, on the DESS images. These regions were applied to the sodium images, and a median sodium signal from each reported. Within-subject and between-subject coefficients of variation were estimated and intraclass correlation coefficients for the healthy control group, OA subject group, and all pooled subjects group were calculated.Within-subject variability of sodium MRI at 3T was 3.2% overall, and 2.0% in healthy age-matched volunteers compared to a reproducibility of 3.6% on OA subjects.The reproducibility of sodium MRI was similar in both healthy controls and OA subjects. Researchers piloting techniques in healthy controls thus may expect a similar reproducibility in a controlled trial involving subjects with American College of Rheumatology (ACR)-defined OA of the knee.

  View details for DOI 10.1016/j.joca.2011.10.007

  View details for Web of Science ID 000299501000006

  View details for PubMedID 22040861

• Advanced MRI of articular cartilage. Imaging in medicine Braun, H. J., Gold, G. E. 2011; 3 (5): 541-555

  Abstract

  Musculoskeletal MRI is advancing rapidly, with innovative technology and significant potential for immediate clinical impact. In particular, cartilage imaging has become a topic of increasing interest as our aging population develops diseases such as osteoarthritis. Advances in MRI hardware and software have led to increased image quality and tissue contrast. Additional developments have allowed the assessment of cartilage macromolecular content, which may be crucial to the early detection of musculoskeletal diseases. This comprehensive article considers current morphological and physiological cartilage imaging techniques, their clinical applications, and their potential to contribute to future improvements in the imaging of cartilage.

  View details for PubMedID 22162977

• Three-dimensional fluid-suppressed T2-prep flow-independent peripheral angiography using balanced SSFP MAGNETIC RESONANCE IMAGING Bangerter, N. K., Cukur, T., Hargreaves, B. A., Hu, B. S., Brittain, J. H., Park, D., Gold, G. E., Nishimura, D. G. 2011; 29 (8): 1119-1124

  Abstract

  Accurate depiction of the vessels of the lower leg, foot or hand benefits from suppression of bright MR signal from lipid (such as bone marrow) and long-T1 fluid (such as synovial fluid and edema). Signal independence of blood flow velocities, good arterial/muscle contrast and arterial/venous separation are also desirable. The high SNR, short scan times and flow properties of balanced steady-state free precession (SSFP) make it an excellent candidate for flow-independent angiography. In this work, a new magnetization-prepared 3D SSFP sequence for flow-independent peripheral angiography is presented. The technique combines a number of component techniques (phase-sensitive fat detection, inversion recovery, T2-preparation and square-spiral phase-encode ordering) to achieve high-contrast peripheral angiograms at only a modest scan time penalty over simple 3D SSFP. The technique is described in detail, a parameter optimization performed and preliminary results presented achieving high contrast and 1-mm isotropic resolution in a normal foot.

  View details for DOI 10.1016/j.mri.2011.04.007

  View details for Web of Science ID 000295195900011

  View details for PubMedID 21705166

  View details for PubMedCentralID PMC3172338

• Cross-relaxation Imaging of Human Articular Cartilage MAGNETIC RESONANCE IN MEDICINE Stikov, N., Keenan, K. E., Pauly, J. M., Smith, R. L., Dougherty, R. F., Gold, G. E. 2011; 66 (3): 725-734

  Abstract

  In this article, cross-relaxation imaging is applied to human ex vivo knee cartilage, and correlations of the cross-relaxation imaging parameters with macromolecular content in articular cartilage are reported. We show that, unlike the more commonly used magnetization transfer ratio, the bound pool fraction, the cross-relaxation rate (k) and the longitudinal relaxation time (T(1)) vary with depth and can therefore provide insight into the differences between the top and bottom layers of articular cartilage. Our cross-relaxation imaging model is more sensitive to macromolecular content in the top layers of cartilage, with bound pool fraction showing moderate correlations with proteoglycan content, and k and T(1) exhibiting moderate correlations with collagen.

  View details for DOI 10.1002/mrm.22865

  View details for Web of Science ID 000293988000013

  View details for PubMedID 21416504

  View details for PubMedCentralID PMC3130884

• Metal-Induced Artifacts in MRI AMERICAN JOURNAL OF ROENTGENOLOGY Hargreaves, B. A., Worters, P. W., Pauly, K. B., Pauly, J. M., Koch, K. M., Gold, G. E. 2011; 197 (3): 547-555

  Abstract

  The purpose of this article is to review some of the basic principles of imaging and how metal-induced susceptibility artifacts originate in MR images. We will describe common ways to reduce or modify artifacts using readily available imaging techniques, and we will discuss some advanced methods to correct readout-direction and slice-direction artifacts.The presence of metallic implants in MRI can cause substantial image artifacts, including signal loss, failure of fat suppression, geometric distortion, and bright pile-up artifacts. These cause large resonant frequency changes and failure of many MRI mechanisms. Careful parameter and pulse sequence selections can avoid or reduce artifacts, although more advanced imaging methods offer further imaging improvements.

  View details for DOI 10.2214/AJR.11.7364

  View details for Web of Science ID 000294165600037

  View details for PubMedID 21862795

• Definition of osteoarthritis on MRI: results of a Delphi exercise OSTEOARTHRITIS AND CARTILAGE Hunter, D. J., Arden, N., Conaghan, P. G., Eckstein, F., Gold, G., Grainger, A., Guermazi, A., Harvey, W., Jones, G., Le Graverand, M. P., Laredo, J. D., Lo, G., Losina, E., Mosher, T. J., Roemer, F., Zhang, W. 2011; 19 (8): 963-969

  Abstract

  Despite a growing body of Magnetic Resonance Imaging (MRI) literature in osteoarthritis (OA), there is little uniformity in its diagnostic application. We envisage in the first instance the definition requiring further validation and testing in the research setting before considering implementation/feasibility testing in the clinical setting. The objective of our research was to develop an MRI definition of structural OA.We undertook a multistage process consisting of a number of different steps. The intent was to develop testable definitions of OA (knee, hip and/or hand) on MRI. This was an evidence driven approach with results of a systematic review provided to the group prior to a Delphi exercise. Each participant of the steering group was allowed to submit independently up to five propositions related to key aspects in MRI diagnosis of knee OA. The steering group then participated in a Delphi exercise to reach consensus on which propositions we would recommend for a definition of structural OA on MRI. For each round of voting, ≥60% votes led to include and ≤20% votes led to exclude a proposition. After developing the proposition one of the definitions developed was tested for its validity against radiographic OA in an extant database.For the systematic review we identified 25 studies which met all of our inclusion criteria and contained relevant diagnostic measure and performance data. At the completion of the Delphi voting exercise 11 propositions were accepted for definition of structural OA on MRI. We assessed the diagnostic performance of the tibiofemoral MRI definition against a radiographic reference standard. The diagnostic performance for individual features was: osteophyte C statistic=0.61, for cartilage loss C statistic=0.73, for bone marrow lesions C statistic=0.72 and for meniscus tear in any region C statistic=0.78. The overall composite model for these four features was a C statistic=0.59. We detected good specificity (1) but less optimal sensitivity (0.46) likely due to detection of disease earlier on MRI.We have developed MRI definition of knee OA that requires further formal testing with regards their diagnostic performance (especially in datasets of persons with early disease), before they are more widely used. Our current analysis suggests that further testing should focus on comparisons other than the radiograph, that may capture later stage disease and thus nullify the potential for detecting early disease that MRI may afford. The propositions are not to detract from, nor to discourage the use of traditional means of diagnosing OA.

  View details for DOI 10.1016/j.joca.2011.04.017

  View details for Web of Science ID 000294240400005

  View details for PubMedID 21620986

• Magnetic resonance guided high-intensity focused ultrasound ablation of musculoskeletal tumors. Current orthopaedic practice Avedian, R. S., Gold, G., Ghanouni, P., Pauly, K. B. 2011; 22 (4): 303-308

  Abstract

  This article reviews the fundamental principles and clinical experimental uses of magnetic resonance guided high-intensity focused ultrasound (MRgHIFU) ablation of musculoskeletal tumors. MRgHIFU is a noninvasive treatment modality that takes advantage of the ability of magnetic resonance to measure tissue temperature and uses this technology to guide high-intensity focused ultrasound waves to a specific focus within the human body that results in heat generation and complete thermal necrosis of the targeted tissue. Adjacent normal tissues are spared because of the accurate delivery of thermal energy, as well as, local blood perfusion that provides a cooling effect. MRgHIFU is approved by the Food and Drug Administration for the treatment of uterine fibroids and is used on an experimental basis to treat breast, prostate, liver, bone, and brain tumors.

  View details for PubMedID 26120376

• Strains Across the Acetabular Labrum During Hip Motion A Cadaveric Model AMERICAN JOURNAL OF SPORTS MEDICINE Safran, M. R., Giordano, G., Lindsey, D. P., Gold, G. E., Rosenberg, J., Zaffagnini, S., Giori, N. J. 2011; 39: 92S-102S

  Abstract

  Labral tears commonly cause disabling intra-articular hip pain and are commonly treated with hip arthroscopy. However, the function and role of the labrum are still unclear.(1) Flexion, adduction, and internal rotation (a position clinically defined as the position for physical examination known as the impingement test) places greatest circumferential strain on the anterolateral labrum and posterior labrum; (2) extension with external rotation (a position clinically utilized during physical examination to assess for posterior impingement and for anterior instability) places significant circumferential strains on the anterior labrum; (3) abduction with external rotation during neutral flexion-extension (the position the extremity rests in when a patient lies supine) places the greatest load on the lateral labrum.Descriptive laboratory study. Methods: Twelve cadaveric hips (age, 79 years) without labral tears or arthritis were studied. Hips were dissected free of soft tissues, except the capsuloligamentous structures. Differential variable reluctance transducers were placed in the labrum anteriorly, anterolaterally, laterally, and posteriorly to record circumferential strains in all 4 regions as the hip was placed in 36 different positions.The posterior labrum had the greatest circumferential strains identified; the peak was in the flexed position, in adduction or neutral abduction-adduction. The greatest strains anteriorly were in flexion with adduction. The greatest strains anterolaterally were in full extension. External rotation had greater strains than neutral rotation and internal rotation. The greatest strains laterally were at 90° of flexion with abduction, and external or neutral rotation. In the impingement position, the anterolateral strain increased the most, while the posterior labrum showed decreased strain (greatest magnitude of strain change). When the hip is externally rotated and in neutral flexion-extension or fully extended, the posterior labrum has significantly increased strain, while the anterolateral labrum strain is decreased.These are the first comprehensive strain data (of circumferential strain) analyzing the whole hip labrum. For the intact labrum, the greatest strain change was at the posterior acetabulum, whereas clinically, acetabular labral tears occur most frequently anterolaterally or anteriorly. The results are consistent with the impingement test as an assessment of anterolateral acetabular labral stress. The hyperextension-rotation test, often used clinically to assess anterior hip instability and posterior impingement, did not show a change in strain anteriorly, but did reveal an increase in strain posteriorly.Although this study does not include muscular forces across the hip joint, it does provide a clue as to the stresses about the labrum through the complete range of motions of the hip, which may help in providing a better understanding of the cause of labral tears and in the protection of labral repairs.

  View details for DOI 10.1177/0363546511414017

  View details for Web of Science ID 000292167400014

  View details for PubMedID 21709038

• New MR Imaging Methods for Metallic Implants in the Knee: Artifact Correction and Clinical Impact JOURNAL OF MAGNETIC RESONANCE IMAGING Chen, C. A., Chen, W., Goodman, S. B., Hargreaves, B. A., Koch, K. M., Lu, W., Brau, A. C., Draper, C. E., Delp, S. L., Gold, G. E. 2011; 33 (5): 1121-1127

  Abstract

  To evaluate two magnetic resonance imaging (MRI) techniques, slice encoding for metal artifact correction (SEMAC) and multiacquisition variable-resonance image combination (MAVRIC), for their ability to correct for artifacts in postoperative knees with metal.A total of 25 knees were imaged in this study. Fourteen total knee replacements (TKRs) in volunteers were scanned with SEMAC, MAVRIC, and 2D fast spin-echo (FSE) to measure artifact extent and implant rotation. The ability of the sequences to measure implant rotation and dimensions was compared in a TKR knee model. Eleven patients with a variety of metallic hardware were imaged with SEMAC and FSE to compare artifact extent and subsequent patient management was recorded.SEMAC and MAVRIC significantly reduced artifact extent compared to FSE (P < 0.0001) and were similar to each other (P = 0.58), allowing accurate measurement of implant dimensions and rotation. The TKRs were properly aligned in the volunteers. Clinical imaging with SEMAC in symptomatic knees significantly reduced artifact (P < 0.05) and showed findings that were on the majority confirmed by subsequent noninvasive or invasive patient studies.SEMAC and MAVRIC correct for metal artifact, noninvasively providing high-resolution images with superb bone and soft tissue contrast.

  View details for DOI 10.1002/jmri.22534

  View details for PubMedID 21509870

• Science to Practice: Can Inflammatory Arthritis Be Monitored by Using MR Imaging with Injected Hyperpolarized C-13-Pyruvate? RADIOLOGY Larson, P. Z., Gold, G. E. 2011; 259 (2): 309–10

  View details for DOI 10.1148/radiol.11110376

  View details for Web of Science ID 000289667300001

  View details for PubMedID 21502386

• Slice Encoding for Metal Artifact Correction With Noise Reduction MAGNETIC RESONANCE IN MEDICINE Lu, W., Pauly, K. B., Gold, G. E., Pauly, J. M., Hargreaves, B. A. 2011; 65 (5): 1352-1357

  Abstract

  Magnetic resonance imaging (MRI) near metallic implants is often hampered by severe metal artifacts. To obtain distortion-free MR images near metallic implants, SEMAC (Slice Encoding for Metal Artifact Correction) corrects metal artifacts via robust encoding of excited slices against metal-induced field inhomogeneities, followed by combining the data resolved from multiple SEMAC-encoded slices. However, as many of the resolved data elements only contain noise, SEMAC-corrected images can suffer from relatively low signal-to-noise ratio. Improving the signal-to-noise ratio of SEMAC-corrected images is essential to enable SEMAC in routine clinical studies. In this work, a new reconstruction procedure is proposed to reduce noise in SEMAC-corrected images. A singular value decomposition denoising step is first applied to suppress quadrature noise in multi-coil SEMAC-encoded slices. Subsequently, the singular value decomposition-denoised data are selectively included in the correction of through-plane distortions. The experimental results demonstrate that the proposed reconstruction procedure significantly improves the SNR without compromising the correction of metal artifacts.

  View details for DOI 10.1002/mrm.22796

  View details for Web of Science ID 000289760800018

  View details for PubMedID 21287596

  View details for PubMedCentralID PMC3079010

• MR Imaging of Articular Cartilage Physiology MAGNETIC RESONANCE IMAGING CLINICS OF NORTH AMERICA Choi, J., Gold, G. E. 2011; 19 (2): 249-?

  Abstract

  The newer magnetic resonance (MR) imaging methods can give insights into the initiation, progression, and eventual treatment of osteoarthritis. Sodium imaging is specific for changes in proteoglycan (PG) content without the need for an exogenous contrast agent. T1ρ imaging is sensitive to early PG depletion. Delayed gadolinium-enhanced MR imaging has high resolution and sensitivity. T2 mapping is straightforward and is sensitive to changes in collagen and water content. Ultrashort echo time MR imaging examines the osteochondral junction. Magnetization transfer provides improved contrast between cartilage and fluid. Diffusion-weighted imaging may be a valuable tool in postoperative imaging.

  View details for DOI 10.1016/j.mric.2011.02.010

  View details for Web of Science ID 000292170100004

  View details for PubMedID 21665090

  View details for PubMedCentralID PMC3115556

• Routine 3D Magnetic Resonance Imaging of Joints JOURNAL OF MAGNETIC RESONANCE IMAGING Kijowski, R., Gold, G. E. 2011; 33 (4): 758-771

  Abstract

  Due to its high spatial resolution and excellent tissue contrast, magnetic resonance imaging (MRI) has become the most commonly used imaging method to evaluate joints. Most musculoskeletal MRI is performed using 2D fast spin-echo sequences. However, 3D sequences have also been used for joint imaging and have the advantage of acquiring thin continuous slices through joints, which reduces the effects of partial volume averaging. With recent advances in MR technology, 3D sequences with isotropic resolution have been developed. These sequences allow high-quality multiplanar reformat images to be obtained following a single acquisition, thereby eliminating the need to repeat sequences with identical tissue contrast in different planes. Preliminary results on the diagnostic performance of 3D isotropic resolution sequences are encouraging. However, additional studies are needed to determine whether these sequences can replace currently used 2D fast spin-echo sequences for providing comprehensive joint assessment in clinical practice.

  View details for DOI 10.1002/jmri.22342

  View details for Web of Science ID 000288913200001

  View details for PubMedID 21448939

  View details for PubMedCentralID PMC3069719

• Phase-sensitive sodium B1 mapping. Magnetic resonance in medicine Allen, S. P., Morrell, G. R., Peterson, B., Park, D., Gold, G. E., Kaggie, J. D., Bangerter, N. K. 2011; 65 (4): 1125-1130

  Abstract

  Quantitative sodium MRI requires accurate knowledge of factors affecting the sodium signal. One important determinant of sodium signal level is the transmit B(1) field strength. However, the low signal-to-noise ratio typical of sodium MRI makes accurate B(1) mapping in reasonable scan times challenging. A new phase-sensitive B(1) mapping technique has recently been shown to work better than the widely used dual-angle method in low-signal-to-noise ratio situations and over a broader range of flip angles. In this work, the phase-sensitive B(1) mapping technique is applied to sodium, and its performance compared to the dual-angle method through both simulation and phantom studies. The phase-sensitive method is shown to yield higher quality B(1) maps at low signal-to-noise ratio and greater consistency of measurement than the dual-angle method. An in vivo sodium B(1) map of the human breast is also shown, demonstrating the phase-sensitive method's feasibility for human studies.

  View details for DOI 10.1002/mrm.22700

  View details for PubMedID 21413078

• Imaging of the Wrist at 1.5 Tesla Using Isotropic Three-Dimensional Fast Spin Echo Cube JOURNAL OF MAGNETIC RESONANCE IMAGING Stevens, K. J., Wallace, C. G., Chen, W., Rosenberg, J. K., Gold, G. E. 2011; 33 (4): 908-915

  Abstract

  To compare three-dimensional fast spin echo Cube (3D-FSE-Cube) with conventional 2D-FSE in MR imaging of the wrist.The wrists of 10 volunteers were imaged in a 1.5 Tesla MRI scanner using an eight-channel wrist coil. The 3D-FSE-Cube images were acquired in the coronal plane with 0.5-mm isotropic resolution. The 2D-FSE images were acquired in both coronal and axial planes for comparison. An ROI was placed in fluid, cartilage, and muscle for SNR analysis. Comparable coronal and axial images were selected for each sequence, and paired images were randomized and graded for blurring, artifact, anatomic details, and overall image quality by three blinded musculoskeletal radiologists.SNR of fluid, cartilage and muscle at prescribed locations were higher using 3D-FSE-Cube, without reaching statistical significance. Fluid-cartilage CNR was also higher with 3D-FSE-Cube, but not statistically significant. Blurring, artifact, anatomic details, and overall image quality were significantly better on coronal 3D-FSE-Cube images (P < 0.001), but significantly better on axial 2D-FSE images compared with axial 3D-FSE-Cube reformats (P < 0.01).Isotropic data from 3D-FSE-Cube allows reformations in arbitrary scan planes, which may make multiple 2D acquisitions unnecessary, and improve depiction of complex wrist anatomy. However, axial reformations suffer from blurring, likely due to T2 decay during the long echo train, limiting overall image quality in this plane.

  View details for DOI 10.1002/jmri.22494

  View details for PubMedID 21448957

• Phase-Sensitive Sodium B-1 Mapping MAGNETIC RESONANCE IN MEDICINE Allen, S. P., Morrell, G. R., Peterson, B., Park, D., Gold, G. E., Kaggie, J. D., Bangerter, N. K. 2011; 65 (4): 1126-1131

  Abstract

  Quantitative sodium MRI requires accurate knowledge of factors affecting the sodium signal. One important determinant of sodium signal level is the transmit B(1) field strength. However, the low signal-to-noise ratio typical of sodium MRI makes accurate B(1) mapping in reasonable scan times challenging. A new phase-sensitive B(1) mapping technique has recently been shown to work better than the widely used dual-angle method in low-signal-to-noise ratio situations and over a broader range of flip angles. In this work, the phase-sensitive B(1) mapping technique is applied to sodium, and its performance compared to the dual-angle method through both simulation and phantom studies. The phase-sensitive method is shown to yield higher quality B(1) maps at low signal-to-noise ratio and greater consistency of measurement than the dual-angle method. An in vivo sodium B(1) map of the human breast is also shown, demonstrating the phase-sensitive method's feasibility for human studies.

  View details for DOI 10.1002/mrm.22700

  View details for Web of Science ID 000288612000026

  View details for PubMedCentralID PMC3073006

• Patellar Maltracking Correlates With Vastus Medialis Activation Delay in Patellofemoral Pain Patients AMERICAN JOURNAL OF SPORTS MEDICINE Pal, S., Draper, C. E., Fredericson, M., Gold, G. E., Delp, S. L., Beaupre, G. S., Besier, T. F. 2011; 39 (3): 590-598

  Abstract

  Delayed onset of vastus medialis (VM) activity compared with vastus lateralis activity is a reported cause for patellofemoral pain. The delayed onset of VM activity in patellofemoral pain patients likely causes an imbalance in muscle forces and lateral maltracking of the patella; however, evidence relating VM activation delay to patellar maltracking is sparse. The aim of this study was to investigate the relationship between VM activation delay and patellar maltracking measures in pain-free controls and patellofemoral pain patients.Patellar tilt and bisect offset, measures of patellar tracking, correlate with VM activation delay in patellofemoral pain patients classified as maltrackers.Case control study; Level of evidence, 3.Vasti muscle activations were recorded in pain-free (n = 15) and patellofemoral pain (n = 40) participants during walking and jogging. All participants were scanned in an open-configuration magnetic resonance scanner in an upright weightbearing position to acquire the position of the patella with respect to the femur. Patellar tilt and bisect offset were measured, and patellofemoral pain participants were classified into normal tracking and maltracking groups.Correlations between VM activation delay and patellar maltracking measures were statistically significant in only the patellofemoral pain participants classified as maltrackers with both abnormal tilt and abnormal bisect offset (R(2) = .89, P < .001, with patellar tilt during walking; R(2) = .75, P = .012, with bisect offset during jogging). There were no differences between the means of activation delays in pain-free and all patellofemoral pain participants during walking (P = .516) or jogging (P = .731).There was a relationship between VM activation delay and patellar maltracking in the subgroup of patellofemoral pain participants classified as maltrackers with both abnormal tilt and abnormal bisect offset.A clinical intervention such as VM retraining may be effective in only a subset of patellofemoral pain participants-namely, those with excessive tilt and excessive bisect offset measures. The results highlight the importance of appropriate classification of patellofemoral pain patients before selection of a clinical intervention.

  View details for DOI 10.1177/0363546510384233

  View details for Web of Science ID 000288063900019

  View details for PubMedID 21076015

• Differences in Patellofemoral Kinematics between Weight-Bearing and Non-Weight-Bearing Conditions in Patients with Patellofemoral Pain JOURNAL OF ORTHOPAEDIC RESEARCH Draper, C. E., Besier, T. F., Fredericson, M., Santos, J. M., Beaupre, G. S., Delp, S. L., Gold, G. E. 2011; 29 (3): 312-317

  Abstract

  Patellar maltracking is thought to be one source of patellofemoral pain. Measurements of patellar tracking are frequently obtained during non-weight-bearing knee extension; however, pain typically arises during highly loaded activities, such as squatting, stair climbing, and running. It is unclear whether patellofemoral joint kinematics during lightly loaded tasks replicate patellofemoral joint motion during weight-bearing activities. The purpose of this study was to: evaluate differences between upright, weight-bearing and supine, non-weight-bearing joint kinematics in patients with patellofemoral pain; and evaluate whether the kinematics in subjects with maltracking respond differently to weight-bearing than those in nonmaltrackers. We used real-time magnetic resonance imaging to visualize the patellofemoral joint during dynamic knee extension from 30° to 0° of knee flexion during two conditions: upright, weight-bearing and supine, non-weight-bearing. We compared patellofemoral kinematics measured from the images. The patella translated more laterally during the supine task compared to the weight-bearing task for knee flexion angles between 0° and 5° (p = 0.001). The kinematics of the maltrackers responded differently to joint loading than those of the non-maltrackers. In subjects with excessive lateral patellar translation, the patella translated more laterally during upright, weight-bearing knee extension for knee flexion angles between 25° and 30° (p = 0.001). However, in subjects with normal patellar translation, the patella translated more laterally during supine, non-weight-bearing knee extension near full extension (p = 0.001). These results suggest that patellofemoral kinematics measured during supine, unloaded tasks do not accurately represent the joint motion during weight-bearing activities.

  View details for DOI 10.1002/jor.21253

  View details for Web of Science ID 000287173500002

  View details for PubMedID 20949442

• Prediction of glycosaminoglycan content in human cartilage by age, T1 rho and T2 MRI OSTEOARTHRITIS AND CARTILAGE Keenan, K. E., Besier, T. F., Pauly, J. M., Han, E., Rosenberg, J., Smith, R. L., Delp, S. L., Beaupre, G. S., Gold, G. E. 2011; 19 (2): 171-179

  Abstract

  A relationship between T1ρ relaxation time and glycosaminoglycan (GAG) content has been demonstrated in chemically degraded bovine cartilage, but has not been demonstrated with quantitative biochemistry in human cartilage. A relationship has also been established between T2 relaxation time in cartilage and osteoarthritis (OA) severity. We hypothesized that T1ρ relaxation time would be associated with GAG content in human cartilage with normal T2 relaxation times.T2 relaxation time, T1ρ relaxation time, and glycosaminoglycan as a percentage of wet weight (sGAG) were measured for top and bottom regions at 7 anatomical locations in 21 human cadaver patellae. For our analysis, T2 relaxation time was classified as normal or elevated based on a threshold defined by the mean plus one standard deviation of the T2 relaxation time for all samples.In the normal T2 relaxation time subset, T1ρ relaxation time correlated with sGAG content in the full-thickness and bottom regions, but only marginally in the top region alone. sGAG content decreased significantly with age in all regions.In the subset of cartilage specimens with normal T2 relaxation time, T1ρ relaxation time was inversely associated with sGAG content, as hypothesized. A predictive model, which accounts for T2 relaxation time and the effects of age, might be able to determine longitudinal trends in GAG content in the same person based on T1ρ relaxation time maps.

  View details for DOI 10.1016/j.joca.2010.11.009

  View details for Web of Science ID 000287470600005

  View details for PubMedID 21112409

  View details for PubMedCentralID PMC3041640

• Comparison of Quadriceps Angle Measurements Using Short-Arm and Long-Arm Goniometers: Correlation With MRI PM&R Draper, C. E., Chew, K. T., Wang, R., Jennings, F., Gold, G. E., Fredericson, M. 2011; 3 (2): 111-116

  Abstract

  To compare the reliability of quadriceps-angle (Q-angle) measurements performed using a short-arm goniometer and a long-arm goniometer and to assess the accuracy of goniometer-based Q-angle measurements compared with anatomic Q angles derived from magnetic resonance imaging (MRI).An intra- and interobserver reliability study.University hospital.Eighteen healthy subjects with no history of knee pain, trauma, or prior surgery were examined.Two physicians, blinded to subject identity, measured Q angles on both knees of all subjects using 2 goniometers: (1) a short-arm goniometer and (2) a long-arm goniometer. Q angles were derived from axial MRIs of the subjects' hip and knees.The intra- and interobserver reliabilities of each goniometer were assessed using the intraclass correlation coefficient (ICC). The comparison between clinical and MRI-based Q angles was assessed by using the ICC and a paired t-test.Intra- and interobserver reliabilities of the long-arm goniometer (intraobserver ICC, 0.92; interobserver ICC, 0.88) were better than those of the short-arm goniometer (intraobserver ICC, 0.78; interobserver ICC, 0.56). Although both goniometers measured Q angles that were moderately correlated to the MRI-based measurements (ICC, 0.40), the clinical Q angles were underestimated compared with the MRI-based anatomic Q angles (P < .05).The results of this study suggest that, although reproducible Q-angle measurements can be performed using standardized patient positioning and a long-arm goniometer, methods to improve the accuracy of clinical Q-angle measurements are needed.

  View details for DOI 10.1016/j.pmrj.2010.10.020

  View details for Web of Science ID 000305437300004

  View details for PubMedID 21333949

• Articular Cartilage in the Knee: Current MR Imaging Techniques and Applications in Clinical Practice and Research RADIOGRAPHICS Crema, M. D., Roemer, F. W., Marra, M. D., Burstein, D., Gold, G. E., Eckstein, F., Baum, T., Mosher, T. J., Carrino, J. A., Guermazi, A. 2011; 31 (1): 37-U76

  Abstract

  Magnetic resonance (MR) imaging is the most important imaging modality for the evaluation of traumatic or degenerative cartilaginous lesions in the knee. It is a powerful noninvasive tool for detecting such lesions and monitoring the effects of pharmacologic and surgical therapy. The specific MR imaging techniques used for these purposes can be divided into two broad categories according to their usefulness for morphologic or compositional evaluation. To assess the structure of knee cartilage, standard spin-echo (SE) and gradient-recalled echo (GRE) sequences, fast SE sequences, and three-dimensional SE and GRE sequences are available. These techniques allow the detection of morphologic defects in the articular cartilage of the knee and are commonly used in research for semiquantitative and quantitative assessments of cartilage. To evaluate the collagen network and proteoglycan content in the knee cartilage matrix, compositional assessment techniques such as T2 mapping, delayed gadolinium-enhanced MR imaging of cartilage (or dGEMRIC), T1ρ imaging, sodium imaging, and diffusion-weighted imaging are available. These techniques may be used in various combinations and at various magnetic field strengths in clinical and research settings to improve the characterization of changes in cartilage.

  View details for DOI 10.1148/rg.311105084

  View details for Web of Science ID 000286608900004

  View details for PubMedID 21257932

• A comparison of four algorithms for metal artifact reduction in CT imaging Conference on Medical Imaging 2011 - Physics of Medical Imaging Golden, C., Mazin, S. R., Boas, F. E., Tye, G., Ghanouni, P., Gold, G., Sofilos, M., Pelc, N. J. SPIE-INT SOC OPTICAL ENGINEERING. 2011

  View details for DOI 10.1117/12.878896

  View details for Web of Science ID 000294178500097

• Analysis of Vertical and Horizontal Circular C-Arm Trajectories Conference on Medical Imaging 2011 - Physics of Medical Imaging Maier, A., Choi, J., Keil, A., Niebler, C., Sarmiento, M., Fieselmann, A., Gold, G., Delp, S., Fahrig, R. SPIE-INT SOC OPTICAL ENGINEERING. 2011

  View details for DOI 10.1117/12.878502

  View details for Web of Science ID 000294178500070

• Imaging Near Metal with a MAVRIC-SEMAC Hybrid MAGNETIC RESONANCE IN MEDICINE Koch, K. M., Brau, A. C., Chen, W., Gold, G. E., Hargreaves, B. A., Koff, M., McKinnon, G. C., Potter, H. G., King, K. F. 2011; 65 (1): 71-82

  Abstract

  The recently developed multi-acquisition with variable resonance image combination (MAVRIC) and slice-encoding metal artifact correction (SEMAC) techniques can significantly reduce image artifacts commonly encountered near embedded metal hardware. These artifact reductions are enabled by applying alternative spectral and spatial-encoding schemes to conventional spin-echo imaging techniques. Here, the MAVRIC and SEMAC concepts are connected and discussed. The development of a hybrid technique that utilizes strengths of both methods is then introduced. The presented technique is shown capable of producing minimal artifact, high-resolution images near total joint replacements in a clinical setting.

  View details for DOI 10.1002/mrm.22523

  View details for Web of Science ID 000285963500009

  View details for PubMedID 20981709

• Three-dimensional T-1, T-2 and proton density mapping with inversion recovery balanced SSFP MAGNETIC RESONANCE IMAGING Newbould, R. D., Skare, S. T., Alley, M. T., Gold, G. E., Bammer, R. 2010; 28 (9): 1374-1382

  Abstract

  By combining a balanced steady-state free precession (bSSFP) readout with an initial inversion pulse, all three contrast parameters, T(1), T(2) and proton density (M(0)), may be rapidly calculated from the signal progression in time. However, here it is shown that this technique is quite sensitive to variation in the applied transmit RF (B(1)) field, leading to pronounced errors in calculated values. Two-dimensional (2D) acquisitions are taxed to accurately quantify the relaxation, as the short RF pulses required by SSFP's rapid TR contain a broad spectrum of excitation angles. A 3D excitation using a large diameter excitation coil was able to correctly quantify the parameters. While the extreme B(1) sensitivity was previously problematic and has precluded use of IR-bSSFP for relaxometry, in this work these obstacles were significantly reduced, allowing the rapid quantification of T(1), T(2) and M(0). The results may further be used to simulate image contrast from common sequences, such as a T(1)-weighted or fluid-attenuated inversion recovery (FLAIR) examination.

  View details for DOI 10.1016/j.mri.2010.06.004

  View details for Web of Science ID 000283906800015

  View details for PubMedID 20692784

• Magnetic Resonance Imaging Near Metal Implants JOURNAL OF MAGNETIC RESONANCE IMAGING Koch, K. M., Hargreaves, B. A., Pauly, K. B., Chen, W., Gold, G. E., King, K. F. 2010; 32 (4): 773-787

  Abstract

  The desire to apply magnetic resonance imaging (MRI) techniques in the vicinity of embedded metallic hardware is increasing. The soft-tissue contrast available with MR techniques is advantageous in diagnosing complications near an increasing variety of MR-safe metallic hardware. Near such hardware, the spatial encoding mechanisms utilized in conventional MRI methods are often severely compromised. Mitigating these encoding difficulties has been the focus of numerous research investigations over the past two decades. Such approaches include view-angle tilting, short echo-time projection reconstruction acquisitions, single-point imaging, prepolarized MRI, and postprocessing image correction. Various technical advances have also enabled the recent development of two alternative approaches that have shown promising clinical potential. Here, the physical principals and proposed solutions to the problem of MRI near embedded metal are discussed.

  View details for DOI 10.1002/jmri.22313

  View details for Web of Science ID 000282764800002

  View details for PubMedID 20882607

• Fabrication of custom-shaped grafts for cartilage regeneration INTERNATIONAL JOURNAL OF ARTIFICIAL ORGANS Koo, S., Hargreaves, B. A., Gold, G. E., Dragoo, J. L. 2010; 33 (10): 731-737

  Abstract

  to create a custom-shaped graft through 3D tissue shape reconstruction and rapid-prototype molding methods using MRI data, and to test the accuracy of the custom-shaped graft against the original anatomical defect.An iatrogenic defect on the distal femur was identified with a 1.5 Tesla MRI and its shape was reconstructed into a three-dimensional (3D) computer model by processing the 3D MRI data. First, the accuracy of the MRI-derived 3D model was tested against a laser-scan based 3D model of the defect. A custom-shaped polyurethane graft was fabricated from the laser-scan based 3D model by creating custom molds through computer aided design and rapid-prototyping methods. The polyurethane tissue was laser-scanned again to calculate the accuracy of this process compared to the original defect.The volumes of the defect models from MRI and laser-scan were 537 mm3 and 405 mm3, respectively, implying that the MRI model was 33% larger than the laser-scan model. The average (±SD) distance deviation of the exterior surface of the MRI model from the laser-scan model was 0.4 ± 0.4 mm. The custom-shaped tissue created from the molds was qualitatively very similar to the original shape of the defect. The volume of the custom-shaped cartilage tissue was 463 mm3 which was 15% larger than the laser-scan model. The average (±SD) distance deviation between the two models was 0.04 ± 0.19 mm.This investigation proves the concept that custom-shaped engineered grafts can be fabricated from standard sequence 3-D MRI data with the use of CAD and rapid-prototyping technology. The accuracy of this technology may help solve the interfacial problem between native cartilage and graft, if the grafts are custom made for the specific defect. The major source of error in fabricating a 3D custom-shaped cartilage graft appears to be the accuracy of a MRI data itself; however, the precision of the model is expected to increase by the utilization of advanced MR sequences with higher magnet strengths.

  View details for Web of Science ID 000284234600006

  View details for PubMedID 21058268

  View details for PubMedCentralID PMC3310388

• Magnetic Resonance Imaging of the Knee: Optimizing 3 Tesla Imaging SEMINARS IN ROENTGENOLOGY Shapiro, L., Staroswiecki, E., Gold, G. 2010; 45 (4): 238-249

  View details for DOI 10.1053/j.ro.2009.12.007

  View details for Web of Science ID 000281363000003

  View details for PubMedID 20727453

  View details for PubMedCentralID PMC2941506

• Advances in musculoskeletal magnetic resonance imaging. Topics in magnetic resonance imaging Gold, G., Shapiro, L., Hargreaves, B., Bangerter, N. 2010; 21 (5): 335-338

  Abstract

  The technology of musculoskeletal magnetic resonance imaging is advancing at a dramatic rate. Magnetic resonance imaging is now done at medium and higher field strengths with more specialized surface coils and with more variable pulse sequences and postprocessing techniques than ever before. These numerable technical advances are advantageous because they lead to an increased signal-to-noise ratio and increased variety of soft tissue contrast options. However, at the same time, they potentially produce more imaging artifacts when compared with past techniques. Substantial technical advances have considerable clinical challenges in musculoskeletal radiology such as postoperative patient imaging, cartilage mapping, and molecular imaging. In this review, we consider technical advances in hardware and software of musculoskeletal magnetic resonance imaging along with their clinical applications.

  View details for DOI 10.1097/RMR.0b013e31823cd195

  View details for PubMedID 22129646

• Radiofrequency coils for musculoskeletal magnetic resonance imaging. Topics in magnetic resonance imaging Asher, K. A., Bangerter, N. K., Watkins, R. D., Gold, G. E. 2010; 21 (5): 315-323

  Abstract

  Dedicated and specialized radiofrequency coils are critical for high quality musculoskeletal magnetic resonance imaging (MRI). Dedicated coils improve the signal to noise ratio, allowing for faster or higher resolution examinations. Transmit-receive coils can reduce heating at high field strength. Finally, novel radiofrequency coils can be used for assessment of tissue biochemistry, as seen with sodium MRI.

  View details for DOI 10.1097/RMR.0b013e31823cd184

  View details for PubMedID 22129644

• In Vivo Sodium Imaging of Human Patellar Cartilage With a 3D Cones Sequence at 3 T and 7 T JOURNAL OF MAGNETIC RESONANCE IMAGING Staroswiecki, E., Bangerter, N. K., Gurney, P. T., Grafendorfer, T., Gold, G. E., Hargreaves, B. A. 2010; 32 (2): 446-451

  Abstract

  To compare signal-to-noise ratios (SNRs) and T*(2) maps at 3 T and 7 T using 3D cones from in vivo sodium images of the human knee.Sodium concentration has been shown to correlate with glycosaminoglycan content of cartilage and is a possible biomarker of osteoarthritis. Using a 3D cones trajectory, 17 subjects were scanned at 3 T and 12 at 7 T using custom-made sodium-only and dual-tuned sodium/proton surface coils, at a standard resolution (1.3 x 1.3 x 4.0 mm(3)) and a high resolution (1.0 x 1.0 x 2.0 mm(3)). We measured the SNR of the images and the T*(2) of cartilage at both 3 T and 7 T.The average normalized SNR values of standard-resolution images were 27.1 and 11.3 at 7 T and 3 T. At high resolution, these average SNR values were 16.5 and 7.3. Image quality was sufficient to show spatial variations of sodium content. The average T*(2) of cartilage was measured as 13.2 +/- 1.5 msec at 7 T and 15.5 +/- 1.3 msec at 3 T.We acquired sodium images of patellar cartilage at 3 T and 7 T in under 26 minutes using 3D cones with high resolution and acceptable SNR. The SNR improvement at 7 T over 3 T was within the expected range based on the increase in field strength. The measured T*(2) values were also consistent with previously published values.

  View details for DOI 10.1002/jmri.22191

  View details for Web of Science ID 000280447300028

  View details for PubMedID 20677276

  View details for PubMedCentralID PMC3008581

• Cartilage Morphology at 3.0T: Assessment of Three-Dimensional Magnetic Resonance Imaging Techniques JOURNAL OF MAGNETIC RESONANCE IMAGING Chen, C. A., Kijowski, R., Shapiro, L. M., Tuite, M. J., Davis, K. W., Klaers, J. L., Block, W. F., Reeder, S. B., Gold, G. E. 2010; 32 (1): 173-183

  Abstract

  To compare six new three-dimensional (3D) magnetic resonance (MR) methods for evaluating knee cartilage at 3.0T.We compared: fast-spin-echo cube (FSE-Cube), vastly undersampled isotropic projection reconstruction balanced steady-state free precession (VIPR-bSSFP), iterative decomposition of water and fat with echo asymmetry and least-squares estimation combined with spoiled gradient echo (IDEAL-SPGR) and gradient echo (IDEAL-GRASS), multiecho in steady-state acquisition (MENSA), and coherent oscillatory state acquisition for manipulation of image contrast (COSMIC). Five-minute sequences were performed twice on 10 healthy volunteers and once on five osteoarthritis (OA) patients. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were measured from the volunteers. Images of the five volunteers and the five OA patients were ranked on tissue contrast, articular surface clarity, reformat quality, and lesion conspicuity. FSE-Cube and VIPR-bSSFP were compared to IDEAL-SPGR for cartilage volume measurements.FSE-Cube had top rankings for lesion conspicuity, overall SNR, and CNR (P < 0.02). VIPR-bSSFP had top rankings in tissue contrast and articular surface clarity. VIPR and FSE-Cube tied for best in reformatting ability. FSE-Cube and VIPR-bSSFP compared favorably to IDEAL-SPGR in accuracy and precision of cartilage volume measurements.FSE-Cube and VIPR-bSSFP produce high image quality with accurate volume measurement of knee cartilage.

  View details for DOI 10.1002/jmri.22213

  View details for Web of Science ID 000279439600021

  View details for PubMedID 20578024

  View details for PubMedCentralID PMC3065186

• Accelerated Slice Encoding for Metal Artifact Correction JOURNAL OF MAGNETIC RESONANCE IMAGING Hargreaves, B. A., Chen, W., Lu, W., Alley, M. T., Gold, G. E., Brau, A. C., Pauly, J. M., Pauly, K. B. 2010; 31 (4): 987-996

  Abstract

  To demonstrate accelerated imaging with both artifact reduction and different contrast mechanisms near metallic implants.Slice-encoding for metal artifact correction (SEMAC) is a modified spin echo sequence that uses view-angle tilting and slice-direction phase encoding to correct both in-plane and through-plane artifacts. Standard spin echo trains and short-TI inversion recovery (STIR) allow efficient PD-weighted imaging with optional fat suppression. A completely linear reconstruction allows incorporation of parallel imaging and partial Fourier imaging. The signal-to-noise ratio (SNR) effects of all reconstructions were quantified in one subject. Ten subjects with different metallic implants were scanned using SEMAC protocols, all with scan times below 11 minutes, as well as with standard spin echo methods.The SNR using standard acceleration techniques is unaffected by the linear SEMAC reconstruction. In all cases with implants, accelerated SEMAC significantly reduced artifacts compared with standard imaging techniques, with no additional artifacts from acceleration techniques. The use of different contrast mechanisms allowed differentiation of fluid from other structures in several subjects.SEMAC imaging can be combined with standard echo-train imaging, parallel imaging, partial-Fourier imaging, and inversion recovery techniques to offer flexible image contrast with a dramatic reduction of metal-induced artifacts in scan times under 11 minutes.

  View details for DOI 10.1002/jmri.22112

  View details for Web of Science ID 000276328200026

  View details for PubMedID 20373445

  View details for PubMedCentralID PMC2894155

• New developments in magnetic resonance imaging techniques for shoulder instability in athletes. Open access journal of sports medicine McAdams, T. R., Fredericson, M., Vogelsong, M., Gold, G. 2010; 1: 137-142

  Abstract

  Magnetic resonance (MR) imaging can be a very useful tool in the evaluation of instability in the athlete's shoulder. Technical options of MR imaging, such as arthrography, higher power magnets, and shoulder positioning, have enhanced MR evaluation of the shoulder. This update discusses the application of new MR techniques to a variety of shoulder instability patterns, including anterior instability, posterior instability, and atraumatic multidirectional instability. Specific applications of MR imaging in the postoperative patient is discussed. Finally, we describe the future directions of MR imaging in the setting of shoulder instability.

  View details for PubMedID 24198551

• Accuracy of 3D Cartilage Models Generated From MR Images Is Dependent on Cartilage Thickness: Laser Scanner Based Validation of In Vivo Cartilage JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME Koo, S., Giori, N. J., Gold, G. E., Dyrby, C. O., Andriacchi, T. P. 2009; 131 (12)

  Abstract

  Cartilage morphology change is an important biomarker for the progression of osteoarthritis. The purpose of this study was to assess the accuracy of in vivo cartilage thickness measurements from MR image-based 3D cartilage models using a laser scanning method and to test if the accuracy changes with cartilage thickness. Three-dimensional tibial cartilage models were created from MR images (in-plane resolution of 0.55 mm and thickness of 1.5 mm) of osteoarthritic knees of ten patients prior to total knee replacement surgery using a semi-automated B-spline segmentation algorithm. Following surgery, the resected tibial plateaus were laser scanned and made into 3D models. The MR image and laser-scan based models were registered to each other using a shape matching technique. The thicknesses were compared point wise for the overall surface. The linear mixed-effects model was used for statistical test. On average, taking account of individual variations, the thickness measurements in MRI were overestimated in thinner (<2.5 mm) regions. The cartilage thicker than 2.5 mm was accurately predicted in MRI, though the thick cartilage in the central regions was underestimated. The accuracy of thickness measurements in the MRI-derived cartilage models systemically varied according to native cartilage thickness.

  View details for DOI 10.1115/1.4000087

  View details for Web of Science ID 000273614400004

  View details for PubMedID 20524727

  View details for PubMedCentralID PMC3072833

• Geography, Structure, and Evolution of Diffusion and Perfusion Lesions in Diffusion and Perfusion Imaging Evaluation For Understanding Stroke Evolution (DEFUSE) STROKE Olivot, J., Mlynash, M., Thijs, V. N., Purushotham, A., Kemp, S., Lansberg, M. G., Wechsler, L., Gold, G. E., Bammer, R., Marks, M. P., Albers, G. W. 2009; 40 (10): 3245-3251

  Abstract

  The classical representation of acute ischemic lesions on MRI is a central diffusion-weighted imaging (DWI) lesion embedded in a perfusion-weighted imaging (PWI) lesion. We investigated spatial relationships between final infarcts and early DWI/PWI lesions before and after intravenous thrombolysis in the Diffusion and perfusion imaging Evaluation For Understanding Stroke Evolution (DEFUSE) study.Baseline and follow-up DWI and PWI lesions and 30-day fluid-attenuated inversion recovery scans of 32 patients were coregistered. Lesion geography was defined by the proportion of the DWI lesion superimposed by a Tmax (time when the residue function reaches its maximum) >4 seconds PWI lesion; Type 1: >50% overlap and Type 2: < or = 50% overlap. Three-dimensional structure was dichotomized into a single lesion (one DWI and one PWI lesion) versus multiple lesions. Lesion reversal was defined by the percentage of the baseline DWI or PWI lesion not superimposed by the early follow-up DWI or PWI lesion. Final infarct prediction was estimated by the proportion of the final infarct superimposed on the union of the DWI and PWI lesions.Single lesion structure with Type 1 geography was present in only 9 patients (28%) at baseline and 4 (12%) on early follow-up. In these patients, PWI and DWI lesions were more likely to correspond with the final infarcts. DWI reversal was greater among patients with Type 2 geography at baseline. Patients with multiple lesions and Type 2 geography at early follow-up were more likely to have early reperfusion.Before thrombolytic therapy in the 3- to 6-hour time window, Type 2 geography is predominant and is associated with DWI reversal. After thrombolysis, both Type 2 geography and multiple lesion structure are associated with reperfusion.

  View details for DOI 10.1161/STROKEAHA.109.558635

  View details for PubMedID 19679845

• Recent Advances in MRI of Articular Cartilage AMERICAN JOURNAL OF ROENTGENOLOGY Gold, G. E., Chen, C. A., Koo, S., Hargreaves, B. A., Bangerter, N. K. 2009; 193 (3): 628-638

  Abstract

  MRI is the most accurate noninvasive method available to diagnose disorders of articular cartilage. Conventional 2D and 3D approaches show changes in cartilage morphology. Faster 3D imaging methods with isotropic resolution can be reformatted into arbitrary planes for improved detection and visualization of pathology. Unique contrast mechanisms allow us to probe cartilage physiology and detect changes in cartilage macromolecules.MRI has great promise as a noninvasive comprehensive tool for cartilage evaluation.

  View details for DOI 10.2214/AJR.09.3042

  View details for Web of Science ID 000269305600007

  View details for PubMedID 19696274

  View details for PubMedCentralID PMC2879429

• Knee Joint: Comprehensive Assessment with 3D Isotropic Resolution Fast Spin-Echo MR Imaging-Diagnostic Performance Compared with That of Conventional MR Imaging at 3.0 T 94th Scientific Assembly and Annual Meeting of the Radiological-Society-of-North-America Kijowski, R., Davis, K. W., Woods, M. A., Lindstrom, M. J., De Smet, A. A., Gold, G. E., Busse, R. F. RADIOLOGICAL SOC NORTH AMERICA. 2009: 486–95

  Abstract

  To determine whether a three-dimensional isotropic resolution fast spin-echo sequence (FSE-Cube) has similar diagnostic performance as a routine magnetic resonance (MR) imaging protocol for evaluating the cartilage, ligaments, menisci, and osseous structures of the knee joint in symptomatic patients at 3.0 T.This prospective, HIPAA-compliant, institutional review board-approved study was performed with a waiver of informed consent. FSE-Cube was added to the routine 3.0-T MR imaging protocol performed in 100 symptomatic patients (54 male patients with a median age of 32 years and 46 female patients with a median age of 33 years) who subsequently underwent arthroscopic knee surgery. All MR imaging studies were independently reviewed twice by two musculoskeletal radiologists. During the first review, the routine MR imaging protocol was used to detect cartilage lesions, ligament tears, meniscal tears, and bone marrow edema lesions. During the second review, FSE-Cube with multiplanar reformations was used to detect these joint abnormalities. With arthroscopic results as the reference standard, the sensitivity and specificity of FSE-Cube and the routine MR imaging protocol in the detection of cartilage lesions, anterior cruciate ligament tears, and meniscal tears were calculated. Permutation tests were used to compare sensitivity and specificity values.FSE-Cube had significantly higher sensitivity (P = .039) but significantly lower specificity (P = .003) than the routine MR imaging protocol for detecting cartilage lesions. There were no significant differences (P = .183-.999) in sensitivity and specificity between FSE-Cube and the routine MR imaging protocol in the detection of anterior cruciate ligament tears, medial meniscal tears, or lateral meniscal tears. FSE-Cube depicted 96.2% of medial collateral ligament tears, 100% of lateral collateral ligament tears, and 85.3% of bone marrow edema lesions identified on images obtained with the routine MR imaging protocol.FSE-Cube has similar diagnostic performance as a routine MR imaging protocol for detecting cartilage lesions, cruciate ligament tears, collateral ligament tears, meniscal tears, and bone marrow edema lesions within the knee joint at 3.0 T.

  View details for DOI 10.1148/radiol.2523090028

  View details for Web of Science ID 000268875900023

  View details for PubMedID 19703886

• Multiecho IDEAL Gradient-Echo Water-Fat Separation for Rapid Assessment of Cartilage Volume at 1.5 T: Initial Experience RADIOLOGY Chen, C. A., Lu, W., John, C. T., Hargreaves, B. A., Reeder, S. B., Delp, S. L., Siston, R. A., Gold, G. E. 2009; 252 (2): 561-567

  Abstract

  Institutional review board approval and informed consent were obtained for this HIPAA-compliant study. The purpose was to prospectively compare multiecho iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) gradient-echo (GRE) magnetic resonance (MR) imaging with three-dimensional fat-suppressed (FS) spoiled GRE (SPGR) MR imaging to evaluate the articular cartilage of the knee. Six healthy volunteer and 10 cadaver knees were imaged at 1.5 T. Signal-to-noise ratio (SNR), SNR efficiency, and cartilage volume were measured. SNR and SNR efficiency were significantly higher with multiecho IDEAL GRE than with FS SPGR imaging (P < .031). Both methods produced equivalent cartilage volumes (overall concordance correlation coefficient, 0.998) with high precision and accuracy. The use of a cartilage phantom confirmed high accuracy in volume measurements and high reproducibility for both methods. Multiecho IDEAL GRE provides high signal intensity in cartilage and synovial fluid and is a promising technique for imaging articular cartilage of the knee.

  View details for DOI 10.1148/radiol.2522081424

  View details for PubMedID 19528355

• SEMAC: Slice Encoding for Metal Artifact Correction in MRI 16th Annual Meeting of the International-Society-of-Magnetic-Resonance-in-Medicine Lu, W., Pauly, K. B., Gold, G. E., Pauly, J. M., Hargreaves, B. A. WILEY-BLACKWELL. 2009: 66–76

  Abstract

  Magnetic resonance imaging (MRI) near metallic implants remains an unmet need because of severe artifacts, which mainly stem from large metal-induced field inhomogeneities. This work addresses MRI near metallic implants with an innovative imaging technique called "Slice Encoding for Metal Artifact Correction" (SEMAC). The SEMAC technique corrects metal artifacts via robust encoding of each excited slice against metal-induced field inhomogeneities. The robust slice encoding is achieved by extending a view-angle-tilting (VAT) spin-echo sequence with additional z-phase encoding. Although the VAT compensation gradient suppresses most in-plane distortions, the z-phase encoding fully resolves distorted excitation profiles that cause through-plane distortions. By positioning all spins in a region-of-interest to their actual spatial locations, the through-plane distortions can be corrected by summing up the resolved spins in each voxel. The SEMAC technique does not require additional hardware and can be deployed to the large installed base of whole-body MRI systems. The efficacy of the SEMAC technique in eliminating metal-induced distortions with feasible scan times is validated in phantom and in vivo spine and knee studies.

  View details for DOI 10.1002/mrm.21967

  View details for Web of Science ID 000267404300008

  View details for PubMedID 19267347

  View details for PubMedCentralID PMC2837371

• Knee muscle forces during walking and running in patellofemoral pain patients and pain-free controls JOURNAL OF BIOMECHANICS Besier, T. F., Fredericson, M., Gold, G. E., Beaupre, G. S., Delp, S. L. 2009; 42 (7): 898-905

  Abstract

  One proposed mechanism of patellofemoral pain, increased stress in the joint, is dependent on forces generated by the quadriceps muscles. Describing causal relationships between muscle forces, tissue stresses, and pain is difficult due to the inability to directly measure these variables in vivo. The purpose of this study was to estimate quadriceps forces during walking and running in a group of male and female patients with patellofemoral pain (n = 27, 16 female; 11 male) and compare these to pain-free controls (n = 16, 8 female; 8 male). Subjects walked and ran at self-selected speeds in a gait laboratory. Lower limb kinematics and electromyography (EMG) data were input to an EMG-driven musculoskeletal model of the knee, which was scaled and calibrated to each individual to estimate forces in 10 muscles surrounding the joint. Compared to controls, the patellofemoral pain group had greater co-contraction of quadriceps and hamstrings (p = 0.025) and greater normalized muscle forces during walking, even though the net knee moment was similar between groups. Muscle forces during running were similar between groups, but the net knee extension moment was less in the patellofemoral pain group compared to controls. Females displayed 30-50% greater normalized hamstring and gastrocnemius muscle forces during both walking and running compared to males (p<0.05). These results suggest that some patellofemoral pain patients might experience greater joint contact forces and joint stresses than pain-free subjects. The muscle force data are available as supplementary material.

  View details for DOI 10.1016/j.jbiomech.2009.01.032

  View details for Web of Science ID 000266299300016

  View details for PubMedID 19268945

  View details for PubMedCentralID PMC2671570

• Using Real-Time MRI to Quantify Altered Joint Kinematics in Subjects with Patellofemoral Pain and to Evaluate the Effects of a Patellar Brace or Sleeve on Joint Motion JOURNAL OF ORTHOPAEDIC RESEARCH Draper, C. E., Besier, T. F., Santos, J. M., Jennings, F., Fredericson, M., Gold, G. E., Beaupre, G. S., Delp, S. L. 2009; 27 (5): 571-577

  Abstract

  Abnormal patellofemoral joint motion is a possible cause of patellofemoral pain, and patellar braces are thought to alleviate pain by restoring normal joint kinematics. We evaluated whether females with patellofemoral pain exhibit abnormal patellofemoral joint kinematics during dynamic, weight-bearing knee extension and assessed the effects of knee braces on patellofemoral motion. Real-time magnetic resonance (MR) images of the patellofemoral joints of 36 female volunteers (13 pain-free controls, 23 patellofemoral pain) were acquired during weight-bearing knee extension. Pain subjects were also imaged while wearing a patellar-stabilizing brace and a patellar sleeve. We measured axial-plane kinematics from the images. Females with patellofemoral pain exhibited increased lateral translation of the patella for knee flexion angles between 0 degrees and 50 degrees (p = 0.03), and increased lateral tilt for knee flexion angles between 0 degrees and 20 degrees (p = 0.04). The brace and sleeve reduced the lateral translation of the patella; however, the brace reduced lateral displacement more than the sleeve (p = 0.006). The brace reduced patellar tilt near full extension (p = 0.001), while the sleeve had no effect on patellar tilt. Our results indicate that some subjects with patellofemoral pain exhibit abnormal weight-bearing joint kinematics and that braces may be effective in reducing patellar maltracking in these subjects.

  View details for DOI 10.1002/jor.20790

  View details for Web of Science ID 000265009900002

  View details for PubMedID 18985690

  View details for PubMedCentralID PMC2891525

• New resource for the computation of cartilage biphasic material properties with the interpolant response surface method COMPUTER METHODS IN BIOMECHANICS AND BIOMEDICAL ENGINEERING Keenan, K. E., Kourtis, L. C., Besier, T. F., Lindsey, D. P., Gold, G. E., Delp, S. L., Beaupre, G. S. 2009; 12 (4): 415-422

  Abstract

  Cartilage material properties are important for understanding joint function and diseases, but can be challenging to obtain. Three biphasic material properties (aggregate modulus, Poisson's ratio and permeability) can be determined using an analytical or finite element model combined with optimisation to find the material properties values that best reproduce an experimental creep curve. The purpose of this study was to develop an easy-to-use resource to determine biphasic cartilage material properties. A Cartilage Interpolant Response Surface was generated from interpolation of finite element simulations of creep indentation tests. Creep indentation tests were performed on five sites across a tibial plateau. A least-squares residual search of the Cartilage Interpolant Response Surface resulted in a best-fit curve for each experimental condition with corresponding material properties. These sites provided a representative range of aggregate moduli (0.48-1.58 MPa), Poisson's ratio (0.00-0.05) and permeability (1.7 x 10(- 15)-5.4 x 10(- 15) m(4)/N s) values found in human cartilage. The resource is freely available from https://simtk.org/home/va-squish.

  View details for DOI 10.1080/10255840802654319

  View details for Web of Science ID 000268912000005

  View details for PubMedID 19675978

  View details for PubMedCentralID PMC2858459

• Ankle: Isotropic MR Imaging with 3D-FSE-Cube-Initial Experience in Healthy Volunteers RADIOLOGY Stevens, K. J., Busse, R. F., Han, E., Brau, A. C., Beatty, P. J., Beaulieu, C. F., Gold, G. E. 2008; 249 (3): 1026-1033

  Abstract

  The purpose of this prospective study was to compare a new isotropic three-dimensional (3D) fast spin-echo (FSE) pulse sequence with parallel imaging and extended echo train acquisition (3D-FSE-Cube) with a conventional two-dimensional (2D) FSE sequence for magnetic resonance (MR) imaging of the ankle. After institutional review board approval and informed consent were obtained and in accordance with HIPAA privacy guidelines, MR imaging was performed in the ankles of 10 healthy volunteers (four men, six women; age range, 25-41 years). Imaging with the 3D-FSE-Cube sequence was performed at 3.0 T by using both one-dimensional- and 2D-accelerated autocalibrated parallel imaging to decrease imaging time. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) with 3D-FSE-Cube were compared with those of the standard 2D FSE sequence. Cartilage, muscle, and fluid SNRs were significantly higher with the 3D-FSE-Cube sequence (P < .01 for all). Fluid-cartilage CNR was similar for both techniques. The two sequences were also compared for overall image quality, blurring, and artifacts. No significant difference for overall image quality and artifacts was demonstrated between the 2D FSE and 3D-FSE-Cube sequences, although the section thickness in 3D-FSE-Cube imaging was much thinner (0.6 mm). However, blurring was significantly greater on the 3D-FSE-Cube images (P < .04). The 3D-FSE-Cube sequence with isotropic resolution is a promising new MR imaging sequence for viewing complex joint anatomy.

  View details for DOI 10.1148/radiol.2493080227

  View details for PubMedID 19011194

• The Influence of Femoral Internal and External Rotation on Cartilage Stresses within the Patellofemoral Joint JOURNAL OF ORTHOPAEDIC RESEARCH Besier, T. F., Gold, G. E., Delp, S. L., Fredericson, M., Beaupre, G. S. 2008; 26 (12): 1627-1635

  Abstract

  Internal and external rotation of the femur plays an important role in defining the orientation of the patellofemoral joint, influencing contact areas, pressures, and cartilage stress distributions. The purpose of this study was to determine the influence of femoral internal and external rotation on stresses in the patellofemoral cartilage. We constructed finite element models of the patellofemoral joint using magnetic resonance (MR) images from 16 volunteers (8 male and 8 female). Subjects performed an upright weight-bearing squat with the knee at 60 degrees of flexion inside an open-MR scanner and in a gait laboratory. Quadriceps muscle forces were estimated for each subject using an electromyographic-driven model and input to a finite element analysis. Hydrostatic and octahedral shear stresses within the cartilage were modeled with the tibiofemoral joint in a "neutral" position and also with the femur rotated internally or externally by 5 degrees increments to +/-15 degrees . Cartilage stresses were more sensitive to external rotation of the femur, compared with internal rotation, with large variation across subjects. Peak patellar shear stresses increased more than 10% with 15 degrees of external rotation in 75% of the subjects. Shear stresses were higher in the patellar cartilage compared to the femoral cartilage and patellar cartilage stresses were more sensitive to femoral rotation compared with femoral cartilage stress. Large variation in the cartilage stress response between individuals reflects the complex nature of the extensor mechanism and has clinical relevance when considering treatment strategies designed to reduce cartilage stresses by altering femoral internal and external rotation.

  View details for DOI 10.1002/jor.20663

  View details for Web of Science ID 000260934700012

  View details for PubMedID 18524000

• Averaging different alignment axes improves femoral rotational alignment in computer-navigated total knee arthroplasty. journal of bone and joint surgery. American volume Siston, R. A., Cromie, M. J., Gold, G. E., Goodman, S. B., Delp, S. L., Maloney, W. J., Giori, N. J. 2008; 90 (10): 2098-2104

  Abstract

  Computer navigation systems generally establish the rotational alignment axis of the femoral component on the basis of user-defined anatomic landmarks. However, navigation systems can also record knee kinematics and average alignment axes established with multiple techniques. We hypothesized that establishing femoral rotational alignment with the use of kinematic techniques is more accurate and precise (repeatable) than the use of anatomic techniques and that establishing femoral rotational alignment by averaging the results of different alignment techniques is more accurate and precise than the use of a single technique.Twelve orthopaedic surgeons used three anatomic and two kinematic alignment techniques to establish femoral rotational alignment axes in a series of nine cadaver knees. The axes derived with the individual anatomic and kinematic techniques as well as the axes derived with six combination techniques--i.e., those involving averaging of the alignments established with two of the individual techniques--were compared against a reference axis established with computed tomography images of each femur.The kinematic methods were not more accurate (did not have smaller mean errors) or more precise (repeatable) than the anatomic techniques. The combination techniques were accurate (five of the six had a mean error of <5 degrees ) and significantly more precise than all but one of the single methods. The percentage of measurements with <5 degrees of error as compared with the reference epicondylar axis was 37% for the individual anatomic techniques, 30% for the individual kinematic techniques, and 58% for the combination techniques.Averaging the results of kinematic and anatomic techniques, which is possible with computer navigation systems, appears to improve the accuracy of rotational alignment of the femoral component. The number of rotational alignment outliers was reduced when combination techniques were used; however, they are still a problem and continued improvement in methods to accurately establish rotation of the femoral component in total knee arthroplasty is needed.

  View details for DOI 10.2106/JBJS.G.00996

  View details for PubMedID 18829906

• Averaging Different Alignment Axes Improves Femoral Rotational Alignment in Computer-Navigated Total Knee Arthroplasty JOURNAL OF BONE AND JOINT SURGERY-AMERICAN VOLUME Siston, R. A., Cromie, M. J., Gold, G. E., Goodman, S. B., Delp, S. L., Maloney, W. J., Giori, N. J. 2008; 90A (10): 2098-2104

  Abstract

  Computer navigation systems generally establish the rotational alignment axis of the femoral component on the basis of user-defined anatomic landmarks. However, navigation systems can also record knee kinematics and average alignment axes established with multiple techniques. We hypothesized that establishing femoral rotational alignment with the use of kinematic techniques is more accurate and precise (repeatable) than the use of anatomic techniques and that establishing femoral rotational alignment by averaging the results of different alignment techniques is more accurate and precise than the use of a single technique.Twelve orthopaedic surgeons used three anatomic and two kinematic alignment techniques to establish femoral rotational alignment axes in a series of nine cadaver knees. The axes derived with the individual anatomic and kinematic techniques as well as the axes derived with six combination techniques--i.e., those involving averaging of the alignments established with two of the individual techniques--were compared against a reference axis established with computed tomography images of each femur.The kinematic methods were not more accurate (did not have smaller mean errors) or more precise (repeatable) than the anatomic techniques. The combination techniques were accurate (five of the six had a mean error of <5 degrees ) and significantly more precise than all but one of the single methods. The percentage of measurements with <5 degrees of error as compared with the reference epicondylar axis was 37% for the individual anatomic techniques, 30% for the individual kinematic techniques, and 58% for the combination techniques.Averaging the results of kinematic and anatomic techniques, which is possible with computer navigation systems, appears to improve the accuracy of rotational alignment of the femoral component. The number of rotational alignment outliers was reduced when combination techniques were used; however, they are still a problem and continued improvement in methods to accurately establish rotation of the femoral component in total knee arthroplasty is needed.

  View details for DOI 10.2106/JBJS.G.00996

  View details for Web of Science ID 000259873300006

• Feasibility of using real-time MRI to measure joint kinematics in 1.5T and open-bore 0.5T systems JOURNAL OF MAGNETIC RESONANCE IMAGING Draper, C. E., Santos, J. M., Kourtis, L. C., Besier, T. F., Fredericson, M., Beaupre, G. S., Gold, G. E., Delp, S. L. 2008; 28 (1): 158-166

  Abstract

  To test the feasibility and accuracy of measuring joint motion with real-time MRI in a 1.5T scanner and in a 0.5T open-bore scanner and to assess the dependence of measurement accuracy on movement speed.We developed an MRI-compatible motion phantom to evaluate the accuracy of tracking bone positions with real-time MRI for varying movement speeds. The measurement error was determined by comparing phantom positions estimated from real-time MRI to those measured using optical motion capture techniques. To assess the feasibility of measuring in vivo joint motion, we calculated 2D knee joint kinematics during knee extension in six subjects and compared them to previously reported measurements.Measurement accuracy decreased as the phantom's movement speed increased. The measurement accuracy was within 2 mm for velocities up to 217 mm/s in the 1.5T scanner and 38 mm/s in the 0.5T scanner. We measured knee joint kinematics with small intraobserver variation (variance of 0.8 degrees for rotation and 3.6% of patellar width for translation).Our results suggest that real-time MRI can be used to measure joint kinematics when 2 mm accuracy is sufficient. They can also be used to prescribe the speed of joint motion necessary to achieve certain measurement accuracy.

  View details for DOI 10.1002/jmri.21413

  View details for Web of Science ID 000257865800021

  View details for PubMedID 18581329

• Early findings of small-animal MRI and small-animal computed tomography correlate with histological changes in a rat model of rheumatoid arthritis NMR IN BIOMEDICINE Lee, S., Greve, J. M., Leaffer, D., Lollini, L., Bailey, P., Gold, G. E., Biswal, S. 2008; 21 (5): 527-536

  Abstract

  With the use of a commonly utilized animal model of rheumatoid arthritis, the central goal of this work was to determine how well the small-animal imaging tools, small-animal MRI (microMRI) and small-animal X-ray computed tomography (microCT), can detect very early histological changes that occur immediately after induction of the disease. Arthritis was induced in rats by injecting complete Freund's adjuvant into the tail. Right hind paws of living rats were evaluated with 4.7 T microMRI with T1-weighted spin echo and inversion recovery sequences. Paw specimens were also evaluated with microCT and by histological examination (n = 29). MicroMR images were scored for the presence of joint effusion, soft tissue swelling, bone marrow changes, and bone erosions. MicroCT measured bone mineral density (BMD). Histology scores were obtained from representative slides from the same rats. The correlation between BMD, MRI and histology was analyzed using linear regression analysis and analysis of covariance. MRI abnormalities were detected on day 5 after induction as joint effusion and soft tissue swelling, followed by bone marrow changes on day 6 and bone erosion on day 8. BMD measured by microCT decreased, the decrease becoming significant on day 7 (P < 0.019). Soft tissue swelling, joint effusion, and bone erosion scores on microMRI correlated with histology (r2 approximately 0.7). Bone marrow changes were seen more clearly with microMRI than by histological examination. Bone loss could be detected earlier by microCT than on histological sections. In conclusion, microMRI and microCT can be used to evaluate early disease changes within 1 week of induction in the adjuvant-induced arthritis model, and have the ability to detect certain manifestations of disease earlier than histological analysis. The use of small-animal imaging techniques potentially allows earlier diagnosis, improved subject stratification, earlier drug implementation, and therefore improved drug trials in animal models of rheumatoid arthritis.

  View details for DOI 10.1002/nbm.1225

  View details for PubMedID 18023077

• Reduction of truncation artifacts in rapid 3D articular cartilage imaging JOURNAL OF MAGNETIC RESONANCE IMAGING Rakow-Penner, R., Gold, G., Daniel, B., Stevens, K., Rosenberg, J., Mazin, S. 2008; 27 (4): 860-865

  Abstract

  To reduce Gibbs ringing artifact in three-dimensional (3D) articular knee cartilage imaging with linear prediction (LP).A reconstruction method using LP in 3D was applied to truncated data sets of six healthy knees. The technique first linearizes the data before applying the prediction algorithm. Three radiologists blindly reviewed and ranked images of the full, truncated, and predicted data sets. Statistical analysis of the radiologists' reviews was performed for image quality, clinical acceptability of the images, and equivalence with the gold standard.LP applied to 3D knee cartilage imaging allows for 40% decreased scan time while providing image quality with statistical equivalence to a full data set.3D spoiled gradient echo imaging (SPGR) knee cartilage imaging requires significant scan time. This 40% reduction in scan time will allow such scans to be more feasible without sacrificing clinical acceptability.

  View details for DOI 10.1002/jmri.21312

  View details for PubMedID 18383247

• Abduction and external rotation in shoulder impingement: An open MR study on healthy volunteers - Initial experience RADIOLOGY Gold, G. E., Pappas, G. P., Blemker, S. S., Whalen, S. T., Campbell, G., McAdams, T. A., Beaulieu, C. F. 2007; 244 (3): 815-822

  Abstract

  To prospectively evaluate rotator cuff contact with the glenoid in healthy volunteers placed in the unloaded and loaded abduction and external rotation (ABER) positions in an open magnetic resonance (MR) imager.The study was institutional review board approved and HIPAA compliant, and informed consent was received. Eight male volunteers with no history of shoulder pain or pathology were imaged in a 0.5-T open MR imager. Volunteers were imaged in an unloaded ABER position with the arm at 90 degrees abduction and in a loaded ABER position, with a 1-kg load that produced an average external rotation of 111 degrees+/-6 (standard deviation). Two radiologists graded rotator cuff contact on a three-point scale. Three-dimensional anatomic models generated from the MR images were used to measure distances. Minimum distances were computed between the tendon insertion sites and the glenoid, acromion, and coracoid for the loaded ABER position. Minimum distances were compared by using a paired Student t test.In the unloaded ABER position, contact was seen between the infraspinatus and supraspinatus tendons and the glenoid in all eight volunteers. In the loaded ABER position, contact was also observed between the infraspinatus and supraspinatus and the posterior and posterosuperior glenoid, respectively. Deformation of the infraspinatus on the glenoid was seen in four volunteers, whereas supraspinatus deformation was only seen in one volunteer. The minimum distance between the supraspinatus insertion and acromion in the loaded ABER position decreased significantly (P<.01). Supraspinatus tendon to glenoid and infraspinatus tendon to glenoid minimum distances also decreased significantly (P<.01).The unloaded and loaded ABER positions resulted in contact of the supraspinatus and infraspinatus with the glenoid in all volunteers. Distances between the rotator cuff insertion sites and the glenoid decreased in the loaded ABER position.

  View details for DOI 10.1148/radiol.2443060998

  View details for PubMedID 17690321

• T-2-selective magnetization preparation pulses IEEE TRANSACTIONS ON MEDICAL IMAGING Vidarsson, L., Cunningham, C., Gold, G. E., Pauly, J. A. 2007; 26 (7): 981-989

  Abstract

  The purpose of this work was to present and evaluate a new method for directly designing T2-selective preparation pulses. Using a modified Shinnar-Le-Roux (SLR) transform, the design of T2-selective pulses becomes equivalent to designing a pair of polynomials one of which represents the longitudinal magnetization and the other the transverse magnetization. The polynomials enable one to directly analyze the various tradeoffs involved in the design. To evaluate the new method, a short-T2-selective magnetization preparation pulse was designed. Following the preparation pulse, a 2D Fourier transform (2DFT) multislice gradient echo sequence was used for imaging. For verification Bloch equation simulations were performed along with both in vivo and phantom scans. Phantom scans showed good signal suppression of long-T2 species. This is supported by good long-T2 signal suppression seen on the in vivo images. Simulations indicate that the pulse is robust to +/-150 Hz B0 inhomogeneities and +/-10% B1 inhomogeneities.

  View details for DOI 10.1109/TMI.2007.897390

  View details for Web of Science ID 000247832700009

  View details for PubMedID 17649911

• Quantitative evaluation of the relaxivity effects of iodine on Gd-DTPA enhanced MR arthrography JOURNAL OF MAGNETIC RESONANCE IMAGING Ganguly, A., Gold, G. E., Pauly, K. B., Mayer, D., Moseley, M. M., Pelc, N. J., Fahrig, R. 2007; 25 (6): 1219-1225

  Abstract

  To quantify the effect of iodine on the gadolinium (Gd) contrast-enhanced signal in MR arthrography.Saline solutions of Gd contrast agent (0-1 mmol/liter) were mixed with iodinated contrast agent (0-185 mmol/liter). The T1 and T2 relaxation constants of these solutions were measured at 1.5T. Different types of commonly used iodinated contrast agents as well as sodium iodide (NaI) solutions were also analyzed.Iodine caused significant T2 shortening and some T1 shortening in Gd contrast solutions. Both contrast agents independently obeyed the standard relaxation relation, and their mixture obeyed a modified version of this relation. The side chains in various iodine molecules and their viscosities affected the relaxation properties differently. For various spin-echo (SE) sequences, the signal from synovial fluid containing different concentrations of the two contrast agents was calculated. The T2-weighted signal appeared to be most affected by the increase in iodine concentrations. In the absence of Gd contrast, all SE sequences showed an initial increase in signal from iodine contrast.A generalized relation for the relaxivities of Gd contrast in the presence of iodine was established. The side chains of iodine contrast were found to alter the relaxivities of Gd contrast. Imaging with proton density (PD)-weighted SE with only iodine contrast agent was found to be feasible.

  View details for DOI 10.1002/jmri.20934

  View details for Web of Science ID 000246824100017

  View details for PubMedID 17520728

• Isotropic MRI of the knee with 3D fast spin-echo extended echo-train acquisition (XETA): Initial experience AMERICAN JOURNAL OF ROENTGENOLOGY Gold, G. E., Busse, R. F., Beehler, C., Han, E., Brau, A. C., Beatty, P. J., Beaulieu, C. F. 2007; 188 (5): 1287-1293

  Abstract

  The purpose of our study was to prospectively compare a recently developed method of isotropic 3D fast spin-echo (FSE) with extended echo-train acquisition (XETA) with 2D FSE and 2D fast recovery FSE (FRFSE) for MRI of the knee.Institutional review board approval, Health Insurance Portability and Accounting Act (HIPAA) compliance, and informed consent were obtained. We studied 10 healthy volunteers and one volunteer with knee pain using 3D FSE XETA, 2D FSE, and 2D FRFSE. Images were obtained both with and without fat suppression. Cartilage and muscle signal-to-noise ratio (SNR) and cartilage-fluid contrast-to-noise ratio (CNR) were compared using a Student's t test. We also compared reformations of 3D FSE XETA with 2D FSE images directly acquired in the axial plane.Cartilage SNR was higher with 3D FSE XETA (56.8 +/- 9 [SD]) compared with the 2D FSE (45.8 +/- 8, p < 0.01) and 2D FRFSE (32.5 +/- 5.3, p < 0.01). Muscle SNR was significantly higher with 3D FSE XETA (52.1 +/- 4.3) than 2D FSE (45.2 +/- 9, p < 0.01) and 2D FRFSE (23.6 +/- 6.2, p < 0.01). Fluid SNR was significantly higher for 2D FSE (144.9 +/- 33) than 3D FSE XETA (104.7 +/- 18, p < 0.01). Compared with 2D FSE and 2D FRFSE, 3D FSE XETA had lower cartilage-fluid CNR due to higher cartilage SNR (p < 0.01). Three-dimensional FSE XETA acquired volumetric data sets with isotropic resolution. Reformatted images in the axial plane were similar to axial 2D FSE acquisitions but with thinner slices.Three-dimensional FSE XETA acquires high-resolution (approximately 0.7 mm) isotropic data with intermediate and T2-weighting that may be reformatted in arbitrary planes. Three-dimensional FSE XETA is a promising technique for MRI of the knee.

  View details for DOI 10.2214/AJR.06.1208

  View details for Web of Science ID 000246013000027

  View details for PubMedID 17449772

• Water-fat separation with IDEAL gradient-echo imaging JOURNAL OF MAGNETIC RESONANCE IMAGING Reeder, S. B., McKenzie, C. A., Pineda, A. R., Yu, H., Shimakawa, A., Brau, A. C., Hargreaves, B. A., Gold, G. E., Brittain, J. H. 2007; 25 (3): 644-652

  Abstract

  To combine gradient-echo (GRE) imaging with a multipoint water-fat separation method known as "iterative decomposition of water and fat with echo asymmetry and least squares estimation" (IDEAL) for uniform water-fat separation. Robust fat suppression is necessary for many GRE imaging applications; unfortunately, uniform fat suppression is challenging in the presence of B(0) inhomogeneities. These challenges are addressed with the IDEAL technique.Echo shifts for three-point IDEAL were chosen to optimize noise performance of the water-fat estimation, which is dependent on the relative proportion of water and fat within a voxel. Phantom experiments were performed to validate theoretical SNR predictions. Theoretical echo combinations that maximize noise performance are discussed, and examples of clinical applications at 1.5T and 3.0T are shown.The measured SNR performance validated theoretical predictions and demonstrated improved image quality compared to unoptimized echo combinations. Clinical examples of the liver, breast, heart, knee, and ankle are shown, including the combination of IDEAL with parallel imaging. Excellent water-fat separation was achieved in all cases. The utility of recombining water and fat images into "in-phase," "out-of-phase," and "fat signal fraction" images is also discussed.IDEAL-SPGR provides robust water-fat separation with optimized SNR performance at both 1.5T and 3.0T with multicoil acquisitions and parallel imaging in multiple regions of the body.

  View details for DOI 10.1002/jmri.20831

  View details for Web of Science ID 000244698800025

  View details for PubMedID 17326087

• Image-based musculoskeletal modeling: Applications, advances, and future opportunities JOURNAL OF MAGNETIC RESONANCE IMAGING Blemker, S. S., Asakawa, D. S., Gold, G. E., Delp, S. L. 2007; 25 (2): 441-451

  Abstract

  Computer models of the musculoskeletal system are broadly used to study the mechanisms of musculoskeletal disorders and to simulate surgical treatments. Musculoskeletal models have historically been created based on data derived in anatomical and biomechanical studies of cadaveric specimens. MRI offers an abundance of novel methods for acquisition of data from living subjects and is revolutionizing the field of musculoskeletal modeling. The need to create accurate, individualized models of the musculoskeletal system is driving advances in MRI techniques including static imaging, dynamic imaging, diffusion imaging, body imaging, pulse-sequence design, and coil design. These techniques apply to imaging musculoskeletal anatomy, muscle architecture, joint motions, muscle moment arms, and muscle tissue deformations. Further advancements in image-based musculoskeletal modeling will expand the accuracy and utility of models used to study musculoskeletal and neuromuscular impairments.

  View details for DOI 10.1002/jmri.20805

  View details for Web of Science ID 000244133000020

  View details for PubMedID 17260405

• Balanced SSFP imaging of the musculoskeletal system JOURNAL OF MAGNETIC RESONANCE IMAGING Gold, G. E., Hargreaves, B. A., Reeder, S. B., Block, W. F., Kijowski, R., Vasanawala, S. S., Kornaat, P. R., Bammer, R., Newbould, R., Bangerter, N. K., Beaulieu, C. F. 2007; 25 (2): 270-278

  Abstract

  Magnetic resonance imaging (MRI), with its unique ability to image and characterize soft tissue noninvasively, has emerged as one of the most accurate imaging methods available to diagnose bone and joint pathology. Currently, most evaluation of musculoskeletal pathology is done with two-dimensional acquisition techniques such as fast spin echo (FSE) imaging. The development of three-dimensional fast imaging methods based on balanced steady-state free precession (SSFP) shows great promise to improve MRI of the musculoskeletal system. These methods may allow acquisition of fluid sensitive isotropic data that can be reformatted into arbitrary planes for improved detection and visualization of pathology. Sensitivity to fluid and fat suppression are important issues in these techniques to improve delineation of cartilage contours, for detection of marrow edema and derangement of other joint structures.

  View details for DOI 10.1002/jmri.20819

  View details for Web of Science ID 000244133000006

  View details for PubMedID 17260387

• Atlas of individual radiographic features in osteoarthritis, revised OSTEOARTHRITIS AND CARTILAGE Altman, R. D., Gold, G. E. 2007; 15: A1-A56

  Abstract

  Develop a radiographic atlas of osteoarthritis (OA) to be used as a template and guide for grading radiographs of osteoarthritic lesions of the hand, hip and knee.The 1995 atlas was reviewed for the images most useful for clinical trials. Replacement images were selected from the Stanford University Radiology Department Picture Archive and Communications System by reviewing consecutive radiographs obtained from patients. Selected images were downloaded without patient identification information. Images were organized by hand, hip and knee. They were reviewed for findings of OA and images grouped into image files by individual findings and degree of change. Both investigators individually selected the most promising images. Final images were selected by consensus. Original electronic images were then cropped and placed in sequence.Individual radiographic features (e.g., osteophytes, joint space narrowing) were recorded for hand (distal interphalangeal joint, proximal interphalangeal joint, trapeziometacarpal joint), hip (acetabular, femoral) and knee (medial compartment, lateral compartment, tibial, femoral); they were also sequenced for normal, 1+, 2+, and 3+ change. Images were made available in print and electronic formats.An updated atlas of radiographic images was produced to assist in grading individual radiographic features of the hand, hip and knee for clinicians and for use in clinical trials.

  View details for DOI 10.1016/j.joca.2006.11.009

  View details for Web of Science ID 000245081900001

  View details for PubMedID 17320422

• Upper limb muscle volumes in adult subjects JOURNAL OF BIOMECHANICS Holzbaur, K. R., Murray, W. M., Gold, G. E., Delp, S. L. 2007; 40 (4): 742-749

  Abstract

  Muscle force-generating properties are often derived from cadaveric studies of muscle architecture. While the relative sizes of muscles at a single upper limb joint have been established in cadaveric specimens, the relative sizes of muscles across upper limb joints in living subjects remain unclear. We used magnetic resonance imaging to measure the volumes of the 32 upper limb muscles crossing the glenohumeral joint, elbow, forearm, and wrist in 10 young, healthy subjects, ranging from a 20th percentile female to a 97th percentile male, based on height. We measured the volume and volume fraction of these muscles. Muscles crossing the shoulder, elbow, and wrist comprised 52.5, 31.4, and 16.0% of the total muscle volume, respectively. The deltoid had the largest volume fraction (15.2%+/-1%) and the extensor indicis propius had the smallest (0.2%+/-0.05%). We determined that the distribution of muscle volume in the upper limb is highly conserved across these subjects with a three-fold variation in total muscle volumes (1427-4426cm(3)). When we predicted the volume of an individual muscle from the mean volume fraction, on average 85% of the variation among subjects was accounted for (average p=0.0008). This study provides normative data that forms the basis for investigating muscle volumes in other populations, and for scaling computer models to more accurately represent the muscle volume of a specific individual.

  View details for Web of Science ID 000245111200005

  View details for PubMedID 17241636

• Moment-generating capacity of upper limb muscles in healthy adults JOURNAL OF BIOMECHANICS Holzbaur, K. R., Delp, S. L., Gold, G. E., Murray, W. M. 2007; 40 (11): 2442-2449

  Abstract

  Muscle strength and volume vary greatly among individuals. Maximum isometric joint moment, a standard measurement of strength, has typically been assessed in young, healthy subjects, whereas muscle volumes have generally been measured in cadavers. This has made it difficult to characterize the relationship between isometric strength and muscle size in humans. We measured maximum isometric moments about the shoulder, elbow, and wrist in 10 young, healthy subjects, ranging in size from a 20th percentile female to a 97th percentile male. The volumes of 32 upper limb muscles were determined from magnetic resonance images of these same subjects, and grouped according to their primary function. The maximum moments produced using the shoulder adductors (67.9+/-28.4 Nm) were largest, and were approximately 6.5(+/-1.2) times greater than those produced using the wrist extensors (10.2+/-4.6 Nm), which were smallest. While there were substantial differences in moment-generating capacity among these 10 subjects, moment significantly covaried with muscle volume of the appropriate functional group, explaining between 95% (p<0.0001; shoulder adductors) and 68% (p=0.004; wrist flexors) of the variation in the maximum isometric joint moments among subjects. While other factors, such as muscle moment arms or neural activation and coordination, can contribute to variation in strength among subjects, they either were relatively constant across these subjects compared to large differences in muscle volumes or they covaried with muscle volume. We conclude that differences in strength among healthy young adults are primarily a consequence of variation in muscle volume, as opposed to other factors.

  View details for DOI 10.1016/j.jbiomech.2006.11.013

  View details for Web of Science ID 000248990600011

  View details for PubMedID 17250841

• Fluid-attenuated inversion-recovery SSFP imaging JOURNAL OF MAGNETIC RESONANCE IMAGING Bangerter, N. K., Hargreaves, B. A., Gold, G. E., Stucker, D. T., Nishimura, D. G. 2006; 24 (6): 1426-1431

  Abstract

  To describe and evaluate a fast, fluid-suppressed 2D multislice steady-state free precession (SSFP) neuroimaging sequence.We developed a fast fluid-attenuated inversion-recovery SSFP sequence for use in neuroimaging. The inversion time (TI) was optimized to yield good cerebrospinal fluid (CSF) suppression while conserving white matter (WM)/lesion contrast across a broad range of flip angles. Multiple SSFP acquisitions were combined using the sum-of-squares (SOS) method to maximize SNR efficiency while minimizing SSFP banding artifacts. We compared our fluid-attenuated inversion-recovery (FLAIR) SSFP sequence with FLAIR fast spin-echo (FSE) in both normal subjects and a volunteer with multiple sclerosis. SNR measurements were performed to ascertain the SNR efficiency of each sequence.Our FLAIR SSFP sequence demonstrated excellent CSF suppression and good gray matter (GM)/WM contrast. Coverage of the entire brain (5-mm slices, 24-cm FOV, 256 x 192 matrix) was achieved with FLAIR SSFP in less than half the scan time of a corresponding FLAIR FSE sequence with similar SNR, yielding improvements of more than 50% in SNR efficiency. Axial scans of a volunteer with multiple sclerosis show clearly visible plaques and very good visualization of brain parenchyma.We have demonstrated the feasibility of a very fast fluid-suppressed neuroimaging technique using SSFP.

  View details for DOI 10.1002/jmri.20743

  View details for Web of Science ID 000242562000031

  View details for PubMedID 17036358

• Iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) fast spin-echo imaging of the ankle: Initial clinical experience AMERICAN JOURNAL OF ROENTGENOLOGY Fuller, S., Reeder, S., Shimakawa, A., Yu, H., Johnson, J., Beaulieu, C., Gold, G. E. 2006; 187 (6): 1442-1447

  Abstract

  Reliable, uniform fat suppression is important. Multiple approaches currently exist, many of which suffer from either suboptimal signal-to-noise ratio (SNR), or the inability to obtain consistent fat suppression around the ankle joint. Our purpose was to test iterative decomposition of water and fat with echo asymmetry and the least-squares estimation (IDEAL) method in combination with fast spin-echo imaging, which is able to achieve reliable high SNR images with uniform fat-water separation.We compared IDEAL fast spin-echo with conventional fat-suppressed fast spin-echo imaging in 33 ankles in 32 patients. Quantitative measurements of SNR and contrast-to-noise ratio efficiency were made, and qualitative diagnostic image quality and fat-suppression scores were determined.We found that the SNR efficiency for both cartilage and fluid was similar for both techniques, and fluid/cartilage contrast-to-noise ratio efficiency was higher with IDEAL fast spin-echo imaging. Fat suppression and diagnostic quality scores using the IDEAL method were superior (p < 0.01) to fat-suppressed fast spin-echo imaging.IDEAL fast spin-echo imaging is a promising technique for MRI of the ankle.

  View details for DOI 10.2214/AJR.05.0930

  View details for Web of Science ID 000242289200010

  View details for PubMedID 17114534

• Dynamic magnetic resonance imaging of muscle function after surgery SKELETAL RADIOLOGY Asakawa, D. S., Blemker, S. S., Gold, G. E., Delp, S. L. 2006; 35 (12): 885-886

  View details for DOI 10.1007/s00256-006-0163-8

  View details for Web of Science ID 000241797800001

  View details for PubMedID 16810541

• T-1- and T-2-weighted fast spin-echo imaging of the brachial plexus and cervical spine with IDEAL water-fat separation JOURNAL OF MAGNETIC RESONANCE IMAGING Reeder, S. B., Yu, H., Johnson, J. W., Shimakawa, A., Brittain, J. H., Pelc, N. J., Beaulieu, C. F., Gold, G. E. 2006; 24 (4): 825-832

  Abstract

  To compare the iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) method with fat-saturated T1-weighted (T1W) and T2W fast spin-echo (FSE) and short-TI inversion recovery (STIR) imaging of the brachial plexus and cervical spine.Images acquired at 1.5T in five volunteers using fat-saturated T1W and T2W FSE imaging and STIR were compared with T1W and T2W IDEAL-FSE images. Examples of T1W and T2W IDEAL-FSE images acquired in patients are also shown.T1W and T2W IDEAL-FSE demonstrated superior fat suppression (P<0.05) and image quality (P<0.05), compared to T1W and T2W fat-saturated FSE, respectively. SNR performance of T1W-IDEAL-FSE was similar to T1W FSE in the spinal cord (P=0.250) and paraspinous muscles (P=0.78), while T2W IDEAL-FSE had superior SNR in muscle (P=0.02) and CSF (P=0.02), and marginally higher cord SNR (P=0.09). Compared to STIR, T2W IDEAL-FSE demonstrated superior image quality (P<0.05), comparable fat suppression (excellent, P=1.0), and higher SNR performance (P<0.001).IDEAL-FSE is a promising method for T1W and T2W imaging of the brachial plexus and cervical spine.

  View details for DOI 10.1002/jmri.20721

  View details for Web of Science ID 000240882000013

  View details for PubMedID 16969792

• Is cartilage thickness different in young subjects with and without patellofemoral pain? OSTEOARTHRITIS AND CARTILAGE Draper, C. E., Besier, T. F., Gold, G. E., Fredericson, M., Fiene, A., Beaupre, G. S., Delp, S. L. 2006; 14 (9): 931-937

  Abstract

  To determine the differences in load-bearing patellofemoral joint cartilage thickness between genders. To determine the differences in load-bearing cartilage thickness between pain-free controls and individuals with patellofemoral pain.The articular cartilage thickness of the patella and anterior femur was estimated from magnetic resonance images in 16 young, pain-free control subjects (eight males, eight females) and 34 young individuals with patellofemoral pain (12 males, 22 females). The average age of all subjects was 28+/-4 years. The cartilage surfaces were divided into regions approximating the location of patellofemoral joint contact during knee flexion. The mean and peak cartilage thicknesses of each region were computed and compared using a repeated-measures Analysis of Variance.On average, males had 22% and 23% thicker cartilage than females in the patella (P < 0.01) and femur (P < 0.05), respectively. Male control subjects had 18% greater peak patellar cartilage thickness than males with patellofemoral pain (P < 0.05); however, we did not detect differences in patellar cartilage thickness between female control subjects and females with patellofemoral pain (P = 0.45). We detected no significant differences in femoral cartilage thickness between the control and pain groups.Thin cartilage at the patella may be one mechanism of patellofemoral pain in male subjects, but is unlikely to be a dominant factor in the development of pain in the female population.

  View details for DOI 10.1016/j.joca.2006.03.006

  View details for Web of Science ID 000239898500012

  View details for PubMedID 16647278

• Articular cartilage of the knee: Rapid three-dimensional MR imaging at 3.0 T with IDEAL balanced steady-State free precession - Initial experience RADIOLOGY Gold, G. E., Reeder, S. B., Yu, H., Kornaat, P., Shimakawa, A. S., Johnson, J. W., Pelc, N. J., Beaulieu, C. F., Brittain, J. H. 2006; 240 (2): 546-551

  Abstract

  Institutional review board approval and informed consent were obtained for this HIPAA-compliant study. In this study, iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) balanced steady-state free precession (bSSFP), fat-suppressed bSSFP, and fat-suppressed spoiled gradient-echo (GRE) sequences for 3.0-T magnetic resonance (MR) imaging of articular knee cartilage were prospectively compared in five healthy volunteers. Cartilage and fluid signal-to-noise ratio (SNR), cartilage-fluid contrast-to-noise ratio (CNR), SNR efficiency, CNR efficiency, image quality, and fat suppression were compared. Fat-suppressed bSSFP and IDEAL bSSFP had higher SNR efficiency of cartilage (P < .01) than did GRE. IDEAL bSSFP had higher cartilage-fluid CNR efficiency than did fat-suppressed bSSFP or GRE (P < .01). Fat-suppressed bSSFP and IDEAL bSSFP had higher image quality than did GRE (P < .01). GRE and IDEAL bSSFP had significantly better fat-water separation or fat saturation than did fat-suppressed bSSFP (P < .05). IDEAL bSSFP is a promising method for imaging articular knee cartilage.

  View details for DOI 10.1148/radiol.2402050288

  View details for Web of Science ID 000239242600029

  View details for PubMedID 16801369

• Advanced magnetic resonance imaging of articular cartilage ORTHOPEDIC CLINICS OF NORTH AMERICA Gold, G. E., Hargreaves, B. A., Stevens, K. J., Beaulieu, C. F. 2006; 37 (3): 331-?

  Abstract

  MRI is one of the most accurate imaging methods available to diagnose disorders of articular cartilage. Conventional two-dimensional and three-dimensional approaches show changes in cartilage morphology. Newer and substantially faster three-dimensional imaging methods show great promise to improve MRI of cartilage. These methods may allow acquisition of fluid-sensitive isotropic data that can be reformatted into arbitrary planes for improved detection and visualization of pathology. Unique MRI contrast mechanisms also allow clinicians to probe cartilage physiology and detect early changes in cartilage macromolecules.

  View details for DOI 10.1016/j.ocl.2006.04.006

  View details for PubMedID 16846765

• Designing long-T-2 suppression pulses for ultrashort echo time imaging MAGNETIC RESONANCE IN MEDICINE Larson, P. E., Gurney, P. T., Nayak, K., Gold, G. E., Pauly, J. M., Nishimura, D. G. 2006; 56 (1): 94-103

  Abstract

  Ultrashort echo time (UTE) imaging has shown promise as a technique for imaging tissues with T2 values of a few milliseconds or less. These tissues, such as tendons, menisci, and cortical bone, are normally invisible in conventional magnetic resonance imaging techniques but have signal in UTE imaging. They are difficult to visualize because they are often obscured by tissues with longer T2 values. In this article, new long-T2 suppression RF pulses that improve the contrast of short-T2 species are introduced. These pulses are improvements over previous long-T2 suppression pulses that suffered from poor off-resonance characteristics or T1 sensitivity. Short-T2 tissue contrast can also be improved by suppressing fat in some applications. Dual-band long-T2 suppression pulses that additionally suppress fat are also introduced. Simulations, along with phantom and in vivo experiments using 2D and 3D UTE imaging, demonstrate the feasibility, improved contrast, and improved sensitivity of these new long-T2 suppression pulses. The resulting images show predominantly short-T2 species, while most long-T2 species are suppressed.

  View details for DOI 10.1002/mrm.20926

  View details for Web of Science ID 000238823600011

  View details for PubMedID 16724304

  View details for PubMedCentralID PMC2942755

• Prepolarized magnetic resonance imaging around metal orthopedic implants MAGNETIC RESONANCE IN MEDICINE Venook, R. D., Matter, N. I., Ramachandran, M., Ungersma, S. E., Gold, G. E., Giori, N. J., Macovski, A., Scott, G. C., Conolly, S. M. 2006; 56 (1): 177-186

  Abstract

  A prepolarized MRI (PMRI) scanner was used to image near metal implants in agar gel phantoms and in in vivo human wrists. Comparison images were made on 1.5- and 0.5-T conventional whole-body systems. The PMRI experiments were performed in a smaller bore system tailored to extremity imaging with a prepolarization magnetic field of 0.4 T and a readout magnetic field of 27-54 mT (1.1-2.2 MHz). Scan parameters were chosen with equal readout gradient strength over a given field of view and matrix size to allow unbiased evaluation of the benefits of lower readout frequency. Results exhibit substantial reduction in metal susceptibility artifacts under PMRI versus conventional scanners. A new artifact quantification technique is also presented, and phantom results confirm that susceptibility artifacts improve as expected with decreasing readout magnetic field using PMRI. This proof-of-concept study demonstrates that prepolarized techniques have the potential to provide diagnostic cross-sectional images for postoperative evaluation of patients with metal implants.

  View details for DOI 10.1002/mrm.20927

  View details for Web of Science ID 000238823600019

  View details for PubMedID 16724303

• Linear combination filtering for T-2-selective imaging of the knee MAGNETIC RESONANCE IN MEDICINE Vidarsson, L., Gold, G. E., Hargreaves, B., Pauly, J. M. 2006; 55 (5): 1191-1196

  Abstract

  Recently a novel T2 selective imaging method based on linear combination (LC) filtering was developed. By linearly combining images acquired with different echo times LC filtering is able to generate images showing only tissues with a preselected range of T2 relaxation times. In this study the use of LC filtering in knee imaging was investigated. Three LC filters were designed: a short LC filter for imaging the knee meniscus, a medium LC filter for articular cartilage, and a long LC filter for synovial fluid. To verify the filter designs, eight phantoms with different T2 relaxation times were imaged. In addition, in vivo images were acquired from four asymptomatic volunteers and a subject with cartilage damage. T2 maps were also generated using the same source images. Signal-to-noise ratio (SNR) measurements were made of the meniscus, cartilage, and fluid regions on the three LC filtered images. The highest SNR was seen in the target tissue on each of the LC filtered images. LC filtering is a new method that can selectively image knee tissues based on their T2.

  View details for DOI 10.1002/mrm.20678

  View details for Web of Science ID 000237151600029

  View details for PubMedID 16586458

• Comparison of quantitative cartilage measurements acquired on two 3.0T MRI systems from different manufacturers JOURNAL OF MAGNETIC RESONANCE IMAGING Kornaat, P. R., Koo, S., Andriacchi, T. P., Bloem, J. L., Gold, G. E. 2006; 23 (5): 770-773

  Abstract

  To investigate the comparability of two osteoarthritis (OA) surrogate endpoints--average cartilage thickness and cartilage volume--acquired from healthy volunteers on two 3.0T magnetic resonance imaging (MRI) systems from different manufacturers.Ten knees of five healthy volunteers were scanned on a 3.0T General Electric (GE) and a 3.0T Philips scanner using a fast three-dimensional fat-suppressed spoiled gradient (SPGR) imaging sequence. The acquisition parameters were optimized beforehand and were kept as comparable as possible on both scanners. For quantitative analysis, the average cartilage thickness and volume of the load-bearing regions of the femoral condyles were compared. Data were analyzed using a univariate repeated-measures analysis of variance (ANOVA) to examine the effects of position, condyle, and imaging system on the measurements.The average cartilage thickness and volume of the load-bearing regions of the femoral condyles did not differ between the two different 3.0T MRI systems (P > 0.05). There was no significant effect of position or condyle on the average cartilage thickness measurements (P > 0.05; range = 0.41-0.93) or cartilage volume (P > 0.05; range = 0.14-0.87).Two OA surrogate endpoints--average cartilage thickness and cartilage volume--acquired on two 3.0T MRI systems from different manufacturers are comparable.

  View details for DOI 10.1002/jmri.20561

  View details for Web of Science ID 000237124800023

  View details for PubMedID 16568430

• Software tools for interactive instruction in radiologic anatomy. Academic radiology Alvarez, A., Gold, G. E., Tobin, B., Desser, T. S. 2006; 13 (4): 512-517

  Abstract

  To promote active learning in an introductory Radiologic Anatomy course through the use of computer-based exercises.DICOM datasets from our hospital PACS system were transferred to a networked cluster of desktop computers in a medical school classroom. Medical students in the Radiologic Anatomy course were divided into four small groups and assigned to work on a clinical case for 45 minutes. The groups used iPACS viewer software, a free DICOM viewer, to view images and annotate anatomic structures. The classroom instructor monitored and displayed each group's work sequentially on the master screen by running SynchronEyes, a software tool for controlling PC desktops remotely.Students were able to execute the assigned tasks using the iPACS software with minimal oversight or instruction. Course instructors displayed each group's work on the main display screen of the classroom as the students presented the rationale for their decisions. The interactive component of the course received high ratings from the students and overall course ratings were higher than in prior years when the course was given solely in lecture format.DICOM viewing software is an excellent tool for enabling students to learn radiologic anatomy from real-life clinical datasets. Interactive exercises performed in groups can be powerful tools for stimulating students to learn radiologic anatomy.

  View details for PubMedID 16554232

• Software tools for interactive instruction in radiologic anatomy ACADEMIC RADIOLOGY Alvarez, A., Gold, G. E., Tobin, B., Desser, T. S. 2006; 13 (4): 510-515

  Abstract

  To promote active learning in an introductory Radiologic Anatomy course through the use of computer-based exercises.DICOM datasets from our hospital PACS system were transferred to a networked cluster of desktop computers in a medical school classroom. Medical students in the Radiologic Anatomy course were divided into four small groups and assigned to work on a clinical case for 45 minutes. The groups used iPACS viewer software, a free DICOM viewer, to view images and annotate anatomic structures. The classroom instructor monitored and displayed each group's work sequentially on the master screen by running SynchronEyes, a software tool for controlling PC desktops remotely.Students were able to execute the assigned tasks using the iPACS software with minimal oversight or instruction. Course instructors displayed each group's work on the main display screen of the classroom as the students presented the rationale for their decisions. The interactive component of the course received high ratings from the students and overall course ratings were higher than in prior years when the course was given solely in lecture format.DICOM viewing software is an excellent tool for enabling students to learn radiologic anatomy from real-life clinical datasets. Interactive exercises performed in groups can be powerful tools for stimulating students to learn radiologic anatomy.

  View details for DOI 10.1016/j.acra.2005.10.005

  View details for Web of Science ID 000236530900015

• Articular cartilage of the knee: Evaluation with fluctuating equilibrium MR imaging - Initial experience in healthy volunteers RADIOLOGY Gold, G. E., Hargreaves, B. A., Vasanawala, S. S., Webb, J. D., Shimakawa, A. S., Brittain, J. H., Beaulieu, C. F. 2006; 238 (2): 712-718

  Abstract

  Institutional review board approval and informed consent were obtained for this HIPAA-compliant study, whose purpose was to prospectively compare three magnetic resonance (MR) imaging techniques-fluctuating equilibrium, three-dimensional (3D) spoiled gradient-recalled acquisition in the steady state (SPGR), and two-dimensional (2D) fast spin echo (SE)-for evaluating articular cartilage in the knee. The study cohort consisted of 10 healthy volunteers (four men, six women; age range, 26-42 years). Cartilage signal-to-noise ratio (SNR), SNR efficiency, cartilage-fluid contrast-to-noise ratio (CNR), CNR efficiency, image quality, cartilage visibility, and fat suppression were compared. Cartilage volume was compared for the fluctuating equilibrium and 3D SPGR techniques. Compared with 3D SPGR and 2D fast SE, fluctuating equilibrium yielded the highest cartilage SNR efficiency and cartilage-fluid CNR efficiency (P < .01 for both). Image quality was similar with all sequences. Fluctuating equilibrium imaging yielded higher cartilage visibility than did 2D fast SE imaging (P <. 01) but worse fat suppression than did 3D SPGR and 2D fast SE imaging (P < .04). Cartilage volume measurements with fluctuating equilibrium and 3D SPGR were similar. Fluctuating equilibrium MR imaging is a promising method for evaluating articular cartilage in the knee.

  View details for DOI 10.1148/radiol.2381042183

  View details for Web of Science ID 000234859100040

  View details for PubMedID 16436826

• MRI and non-cartilaginous structures in knee osteoarthritis Workshop for Consensus on Osteoarthritis Imaging Conaghan, P. G., Felson, D., Gold, G., Lohmander, S., TOTTERMAN, S., Altman, R. W B SAUNDERS CO LTD. 2006: A87–A94

  Abstract

  Magnetic resonance imaging (MRI) provides a sensitive tool for examining all the structures involved in the osteoarthritis (OA) process. While much of the MRI literature previously focussed on cartilage, there is increasing research on whole-organ evaluation and including features such as synovitis, bone marrow edema, and meniscal and ligamentous pathology. The aim of this session at the Outcome Measures in Rheumatology Clinical Trials (OMERACT)-Osteoarthritis Research Society International (OARSI) Workshop for Consensus in Osteoarthritis Imaging was to describe the current MRI methods for identifying and quantifying non-cartilaginous structures and review their associations with both OA symptoms and structural progression. Although there is much experience in measuring synovitis (derived from the rheumatoid arthritis literature), only one study has reported an association of MRI-detected synovitis and effusions with OA pain. Bone marrow edema lesions, which may represent areas of trabecular remodelling, have been associated with pain and compartment-specific structural deterioration. MRI studies have confirmed the frequency and importance of meniscal damage in progressive cartilage loss, but not related such damage to symptoms. Osteophytes have been associated with cartilage loss and malalignment to the side of the osteophyte. Ligament damage, including anterior cruciate ligament tears, has been found more commonly than expected in painful OA knees. Improvements in quantitative and semi-quantitative assessments of non-cartilage features will greatly assist understanding of the OA process and its response to therapy.

  View details for DOI 10.1016/j.joca.2006.02.028

  View details for Web of Science ID 000238959700012

  View details for PubMedID 16713722

• In vivo anatomy of the Neer and Hawkins sign positions for shoulder impingement JOURNAL OF SHOULDER AND ELBOW SURGERY Pappas, G. P., Blemker, S. S., Beaulieu, C. F., McAdams, T. R., Whalen, S. T., Gold, G. E. 2006; 15 (1): 40-49

  Abstract

  The Neer and Hawkins impingement signs are commonly used to diagnose subacromial pathology, but the anatomy of these maneuvers has not been well elucidated in vivo. This 3-dimensional open magnetic resonance imaging study characterized shoulder anatomy and rotator cuff impingement in 8 normal volunteers placed in the Neer and Hawkins positions. Subacromial and intraarticular contact of the rotator cuff was graded, and minimum distances were computed between the tendon insertion sites and the glenoid, acromion, and coracoid. Both the Neer and Hawkins maneuvers significantly decreased the distance from the supraspinatus insertion to the acromion and posterior glenoid and from the subscapularis insertion to the anterior glenoid. However, the Hawkins position resulted in significantly greater subacromial space narrowing and subacromial rotator cuff contact than the Neer position. In the Hawkins position, subacromial contact of the supraspinatus and infraspinatus was observed in 7 of 8 and 5 of 8 subjects, respectively. In contrast, rotator cuff contact with the acromion did not occur in any subject in the Neer position. Intraarticular contact of the supraspinatus with the posterosuperior glenoid was observed in all subjects in both positions. Subscapularis contact with the anterior glenoid was also seen in 7 of 8 subjects in the Neer position and in all subjects in the Hawkins position. This extensive intraarticular contact suggests that internal impingement may play a role in the Neer and Hawkins signs.

  View details for DOI 10.1016/j.jse.2005.04.007

  View details for PubMedID 16414467

• MRI of articular cartilage in OA: novel pulse sequences and compositional/functional markers Workshop for Consensus on Osteoarthritis Imaging Gold, G. E., Burstein, D., Dardzinski, B., Lang, P., Boada, F., Mosher, T. W B SAUNDERS CO LTD. 2006: A76–A86

  Abstract

  Osteoarthritis (OA) is a leading cause of disability worldwide. Magnetic resonance imaging (MRI), with its unique ability to image and characterize soft tissue non-invasively, has proven valuable in assessing cartilage in OA. The development of new, fast imaging methods with high contrast show promise to improve the magnetic resonance (MR) evaluation of this disease. In addition to morphologic MRI methods, MRI contrast mechanisms under development may reveal detailed information about the physiology of cartilage. It is anticipated that these and other MRI techniques will play an increasingly important role in assessing the success or failure of therapies for OA. On December 5 and 6, 2002, OMERACT (Outcome Measures in Rheumatology Clinical Trials) and OARSI (Osteoarthritis Research Society International) held a workshop in Bethesda, MD aiming at providing a state-of-the-art review of imaging outcome measures for OA of the knee to help guide scientists and pharmaceutical companies in the use of MRI in multi-site studies of OA. Applications of MRI were initially reviewed by a multidisciplinary, international panel of expert scientists and physicians from academia, the pharmaceutical industry and regulatory agencies. The findings of the panel were then presented to a wider group of participants for open discussion. The following report summarizes the results of these discussions with respect to novel MRI pulse sequences for evaluating articular cartilage of the knee in OA and notes any additional advances that have been made since.

  View details for Web of Science ID 000238959700011

  View details for PubMedID 16716605

• MRI protocols for whole-organ assessment of the knee in osteoarthritis Workshop for Consensus on Osteoarthritis Imaging Peterfy, C. G., Gold, G., Eckstein, F., Cicuttini, F., Dardzinski, B., Stevens, R. W B SAUNDERS CO LTD. 2006: A95–A111

  Abstract

  One of the critical challenges in developing structure-modifying therapies for arthritis, especially osteoarthritis (OA), is measuring changes in progression of joint destruction. Magnetic resonance imaging (MRI) offers considerable promise in this regard. Not only can MRI quantify articular cartilage volume and morphology with high precision and accuracy, but it can also examine several other important articular components, and thus offer a unique opportunity to evaluate the knee and other joints as whole organs. On December 5 and 6, 2002, OMERACT (Outcome Measures in Rheumatology Clinical Trials) and OARSI (Osteoarthritis Research Society International), with support from various pharmaceutical companies listed at the beginning of this supplement, held a Workshop for Consensus on Osteoarthritis Imaging in Bethesda, MD. The aim of the Workshop was to provide a state-of-the-art review of imaging outcome measures for OA of the knee to help guide scientists and pharmaceutical companies who want to use MRI in multi-site studies of OA. Applications of MRI were initially reviewed by a multidisciplinary, international panel of expert scientists and physicians from academia, the pharmaceutical industry and regulatory agencies. The findings of the panel were then presented to a wider group of participants for open discussion. The following report summarizes the results of these discussions with respect to MRI acquisition techniques for whole-organ assessment of the knee in OA. The discussion reviews the selection and qualification of imaging sites for clinical trials, designing imaging protocols for whole-organ assessment of OA, and key considerations in image quality (IQ) control and data management.

  View details for DOI 10.1016/j.joca.2006.02.029

  View details for Web of Science ID 000238959700013

  View details for PubMedID 16750915

• A modeling framework to estimate patellofemoral joint cartilage stress in vivo MEDICINE AND SCIENCE IN SPORTS AND EXERCISE Besier, T. F., Gold, G. E., Beaupre, G. S., Delp, S. L. 2005; 37 (11): 1924-1930

  Abstract

  Patellofemoral (PF) pain is common among athletes and may be caused by increased subchondral bone stress as a result of increased stress in the cartilage of the femur or patella. This article presents a modeling pipeline to estimate in vivo cartilage stress in the PF joint.The modeling pipeline uses the finite element method to calculate stresses and strains in the PF joint cartilage. Model inputs include an accurate geometrical representation of the bones and cartilage from magnetic resonance imaging (MRI), cartilage material properties, and an estimate of muscle forces from an EMG-driven musculoskeletal model. Validation is performed using PF joint contact area and patellar orientation measured from upright, weight-bearing MRI. Preliminary data from an active, pain-free subject illustrate the modeling pipeline to calculate cartilage stress during a static squat.The quasistatic finite element simulation reproduced the orientation of the patella to within 2.1 mm and predicted the PF joint contact area to within 2.3%. Octahedral shear stresses were highest in the central, lateral aspect of the patella cartilage with a peak of 2.5 MPa. The corresponding stresses in the femoral cartilage reached only 2.0 MPa. However, peak hydrostatic pressures were higher within the femoral cartilage (3.5 MPa) than the patellar cartilage (2.3 MPa).The methods presented in this article offer a novel approach to calculate PF joint cartilage stress in vivo. Future efforts will use this modeling pipeline to further our knowledge of PF pain and potential rehabilitation strategies.

  View details for DOI 10.1249/01.mss.0000176686.18683.64

  View details for Web of Science ID 000233451000015

  View details for PubMedID 16286863

• Automatic tuning of flexible interventional RF receiver coils MAGNETIC RESONANCE IN MEDICINE Venook, R. D., Hargreaves, B. A., Gold, G. E., Conolly, S. M., Scott, G. C. 2005; 54 (4): 983-993

  Abstract

  Microcontroller-based circuitry was built and tested for automatically tuning flexible RF receiver coils at the touch of a button. This circuitry is robust to 10% changes in probe center frequency, is in line with the scanner, and requires less than 1 s to tune a simple probe. Images were acquired using this circuitry with a varactor-tunable 1-inch flexible probe in a phantom and in an in vitro porcine knee model. The phantom experiments support the use of automatic tuning by demonstrating 30% signal-to-noise ratio (SNR) losses for 5% changes in coil center frequency, in agreement with theoretical calculations. Comparisons between patellofemoral cartilage images obtained using a 3-inch surface coil and the surgically-implanted 1-inch flexible coil reveal a worst-case local SNR advantage of a factor of 4 for the smaller coil. This work confirms that surgically implanted coils can greatly improve resolution in small-field-of-view (FOV) applications, and demonstrates the importance and feasibility of automatically tuning such probes.

  View details for DOI 10.1002/mrm.20616

  View details for Web of Science ID 000232348000027

  View details for PubMedID 16155871

• Iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL): Application with fast spin-echo imaging MAGNETIC RESONANCE IN MEDICINE Reeder, S. B., Pineda, A. R., Wen, Z. F., Shimakawa, A., Yu, H. Z., Brittain, J. H., Gold, G. E., Beaulieu, C. H., Pelc, N. J. 2005; 54 (3): 636-644

  Abstract

  Chemical shift based methods are often used to achieve uniform water-fat separation that is insensitive to Bo inhomogeneities. Many spin-echo (SE) or fast SE (FSE) approaches acquire three echoes shifted symmetrically about the SE, creating time-dependent phase shifts caused by water-fat chemical shift. This work demonstrates that symmetrically acquired echoes cause artifacts that degrade image quality. According to theory, the noise performance of any water-fat separation method is dependent on the proportion of water and fat within a voxel, and the position of echoes relative to the SE. To address this problem, we propose a method termed "iterative decomposition of water and fat with echo asymmetric and least-squares estimation" (IDEAL). This technique combines asymmetrically acquired echoes with an iterative least-squares decomposition algorithm to maximize noise performance. Theoretical calculations predict that the optimal echo combination occurs when the relative phase of the echoes is separated by 2pi/3, with the middle echo centered at pi/2+pik (k=any integer), i.e., (-pi/6+pik, pi/2+pik, 7pi/6+pik). Only with these echo combinations can noise performance reach the maximum possible and be independent of the proportion of water and fat. Close agreement between theoretical and experimental results obtained from an oil-water phantom was observed, demonstrating that the iterative least-squares decomposition method is an efficient estimator.

  View details for DOI 10.1002/mrm.20624

  View details for Web of Science ID 000231494000015

  View details for PubMedID 16092103

• Considerations in measuring cartilage thickness using MRI: factors influencing reproducibility and accuracy OSTEOARTHRITIS AND CARTILAGE Koo, S., Gold, G. E., Andriacchi, T. P. 2005; 13 (9): 782-789

  Abstract

  The primary goal of this study was to describe and evaluate conditions that could influence the precision and accuracy of measuring in vivo cartilage thickness in the weight bearing regions of the knee from magnetic resonance imaging (MRI).Three-dimensional (3D) models of the femoral cartilage were created from segmented MR images. The weight bearing regions on femoral cartilage were selected for the portion of the tibiofemoral joint that sustains contact during walking. Six regions of interest (three on each condyle) were located on the femur. Average cartilage thickness was calculated over each region. The sensitivity of the precision of the measurements to observer variability was evaluated using intra- and inter-observer reproducibility tests of cartilage thickness measurements from the MRI-derived 3D models. In addition, the quantitative influence of a rule-based protocol for segmentation was evaluated using the inter-observer reproducibility protocol. Accuracy tests were conducted on porcine knees by comparing 3D models from MR images and laser scans across weight bearing and non-weight bearing regions.The precision was substantially better for the intra-observer tests (Coefficient of variation (CV) = 1-3%) than the inter-observer tests. Adding a rule-based protocol reduced variability in inter-observer tests substantially (CV = 6.6% vs 8.3%). Accuracy tests showed that the central and weight bearing regions on each condyle were more accurate than boundary and non-weight bearing regions. In addition, these results indicate that care should be taken when determining cartilage thickness of weight bearing regions with cartilage degenerations, since the thickness of thinner cartilage can be systematically overestimated in MR images.A rule-based approach can substantially increase inter-observer reproducibility when measuring cartilage thickness from multiple observers. This improvement in inter-observer reproducibility could be an important consideration for longitudinal studies of disease progression. In quantifying cartilage thickness, central and weight bearing regions on each condyle can provide more accurate measurement than boundary and non-weight bearing regions with average accuracy of +/-0.2-0.3 mm. An important finding of this study was that the weight bearing regions, which are usually of the greatest clinical interest, were measured most accurately by sagittal plane imaging.

  View details for DOI 10.1016/j.joca.2005.04.013

  View details for Web of Science ID 000232252100005

  View details for PubMedID 15961328

• MRI findings of femoral diaphyseal stress injuries in athletes AMERICAN JOURNAL OF ROENTGENOLOGY Hwang, B., Fredericson, M., Chung, C. B., Beaulieu, C. F., Gold, G. E. 2005; 185 (1): 166-173

  View details for Web of Science ID 000229951900029

  View details for PubMedID 15972418

• Controversies in protocol selection in the Imaging of articular cartilage SEMINARS IN MUSCULOSKELETAL RADIOLOGY Gold, G. E., Hargreaves, B. A., Reeder, S. B., Vasanawala, S. S., Beaulieu, C. F. 2005; 9 (2): 161-172

  Abstract

  Magnetic resonance (MR) imaging, with its unique ability to noninvasively image and characterize soft tissue, has shown promise in assessment of cartilage. The development of new, fast imaging methods with high contrast will improve the MR evaluation of cartilage morphology. In addition to morphological MR imaging methods, MR imaging contrast mechanisms under development may reveal detailed information regarding the physiology of cartilage. However, many of these methods remain to be tested in the clinical setting. Protocol selection for cartilage imaging requires understanding of the patient population and the advantages and limitations of these techniques.

  View details for Web of Science ID 000230039200008

  View details for PubMedID 16044384

• Rapid musculoskeletal MRI with phase-sensitive steady-state free precession: Comparison with routine knee MRI AMERICAN JOURNAL OF ROENTGENOLOGY Vasanawala, S. S., Hargreaves, B. A., Pauly, J. M., Nishimura, D. G., Beaulieu, C. F., Gold, G. E. 2005; 184 (5): 1450-1455

  Abstract

  The aim of this work was to show the potential utility of a novel rapid 3D fat-suppressed MRI method for joint imaging.Phase-sensitive steady-state free precession provides rapid 3D joint imaging with robust fat suppression and excellent cartilage delineation.

  View details for Web of Science ID 000228875300013

  View details for PubMedID 15855095

• Driven equilibrium magnetic resonance imaging of articular cartilage: Initial clinical experience JOURNAL OF MAGNETIC RESONANCE IMAGING Gold, G. E., Fuller, S. E., Hargreaves, B. A., Stevens, K. J., Beaulieu, C. F. 2005; 21 (4): 476-481

  Abstract

  To evaluate three-dimensional driven equilibrium Fourier transform (3D-DEFT) for image quality and detection of articular cartilage lesions in the knee.We imaged 104 consecutive patients with knee pain with 3D-DEFT and proton density (PD-FSE) and T2-weighted (T2-FSE) fast spin echo. Twenty-four went on to arthroscopy. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) efficiency were measured. Subjective image quality, fat suppression, and cartilage thickness visibility were assessed. Cartilage lesions on 3D-DEFT and T2-FSE were compared with findings outlined in operative reports.SNR efficiency was higher for 3D-DEFT and PD-FSE than for T2-FSE (P < 0.02). 3D-DEFT and PD-FSE showed superior cartilage thickness visibility compared with T2-FSE (P < 0.02). T2-FSE showed better fat suppression and fewer image artifacts than 3D-DEFT (P < 0.04). 3D-DEFT had similar sensitivity and similar specificity for cartilage lesions compared with PD-FSE and T2-FSE.3D-DEFT provides excellent synovial fluid-to-cartilage contrast while preserving signal from cartilage, giving this method a high cartilage SNR. 3D-DEFT shows the full cartilage thickness better than T2-FSE. T2-FSE had superior fat saturation and fewer artifacts than 3D-DEFT. Overall, 3D-DEFT requires further technical development, but is a promising method for imaging articular cartilage.

  View details for DOI 10.1002/jhmi.20276

  View details for PubMedID 15779031

• MR imaging of articular cartilage at 1.5T and 3.0T: Comparison of SPGR and SSFP sequences 9th World Congress of the OsteoArthritis-Research-Society-International Kornaat, P. R., Reeder, S. B., Koo, S., Brittain, J. H., Yu, H., Andriacchi, T. P., Gold, G. E. ELSEVIER SCI LTD. 2005: 338–44

  Abstract

  To compare articular cartilage signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and thickness measurements on a 1.5 T and a 3.0 T magnetic resonance (MR) scanner using three-dimensional spoiled gradient recalled echo (3D-SPGR) and two 3D steady-state free precession (SSFP) sequences.Both knees of five volunteers were scanned at 1.5 T and at 3.0 T using a transmit-receive quadrature extremity coil. Each examination consisted of a sagittal 3D-SPGR sequence, a sagittal fat suppressed 3D-SSFP (FS-SSFP) sequence, and a sagittal Dixon 3D-SSFP sequence. For quantitative analysis, we compared cartilage SNR and CNR efficiencies, as well as average cartilage thickness measurements.For 3D-SPGR, cartilage SNR efficiencies at 3.0 T increased compared to those at 1.5 T by a factor of 1.83 (range: 1.40-2.09). In comparison to 3D-SPGR, the SNR efficiency of FS-SSFP increased by a factor of 2.13 (range: 1.81-2.39) and for Dixon SSFP by a factor of 2.39 (range: 1.95-2.99). For 3D-SPGR, CNR efficiencies between cartilage and its surrounding tissue increased compared to those at 1.5 T by a factor of 2.12 (range: 1.75-2.47), for FS-SSFP by a factor 2.11 (range: 1.58-2.80) and for Dixon SSFP by a factor 2.39 (range 2.09-2.83). Average cartilage thicknesses of load bearing regions were not different at both field strengths or between sequences (P>0.05). Mean average cartilage thickness measured in all knees was 2.28 mm.Articular cartilage imaging of the knee on a 3.0 T MR scanner shows increased SNR and CNR efficiencies compared to a 1.5 T scanner, where SSFP-based techniques show the highest increase in SNR and CNR efficiency. There was no difference between average cartilage thickness measurements performed at the 1.5 T and 3.0 T scanners or between the three different sequences.

  View details for DOI 10.1016/j.joca.2004.12.008

  View details for Web of Science ID 000228216200008

  View details for PubMedID 15780647

• Patellofemoral joint contact area increases with knee flexion and weight-bearing JOURNAL OF ORTHOPAEDIC RESEARCH Besier, T. F., Draper, C. E., Gold, G. E., Beaupre, G. S., Delp, S. L. 2005; 23 (2): 345-350

  Abstract

  Patellofemoral pain is a common and debilitating disorder. Elevated cartilage stress of the patellofemoral joint is hypothesized to play a role in the onset of pain. Estimating cartilage stress requires accurate measurements of contact area. The purpose of this study was to estimate patellofemoral joint contact areas in a group of healthy, pain-free subjects during upright, weight-bearing conditions. Sixteen subjects (8 female, 8 male) were scanned in a GE Signa SP open configuration MRI scanner, which allowed subjects to stand or squat while reclining 25 degrees from vertical with the knee positioned at 0 degrees , 30 degrees , or 60 degrees of flexion. A custom-built backrest enabled subjects to be scanned without motion artifact in both weight-bearing (0.45 body weight per leg) and reduced loading conditions ('unloaded' at 0.15 body weight) at each knee flexion posture. Male subjects displayed mean unloaded patellofemoral joint contact areas of 210, 414, and 520 mm(2) at 0 degrees , 30 degrees and 60 degrees of knee flexion, respectively. Female subjects' unloaded contact areas were similar at full extension (0 degrees ), but significantly smaller at 30 degrees and 60 degrees (p<0.01), with mean values of 269 and 396 mm(2), respectively. When normalized by patellar dimensions (heightxwidth), contact areas were not different between genders. Under weight-bearing conditions, contact areas increased by an average of 24% (p<0.05). This study highlights the differences in patellofemoral joint contact area between gender, knee flexion postures, and physiologic loading conditions.

  View details for DOI 10.1016/j.orthres.2004.08.003

  View details for Web of Science ID 000227567100017

  View details for PubMedID 15734247

• Echo time optimization for linear combination myelin Imaging MAGNETIC RESONANCE IN MEDICINE Vidarsson, L., Conolly, S. M., Lim, K. O., Gold, G. E., Pauly, J. M. 2005; 53 (2): 398-407

  Abstract

  A 3-echo linear combination myelin imaging method is presented. The echo times and weights are chosen such that the signal-to-noise ratio (SNR) of myelin-water is maximized, and signals from other white matter components are sufficiently suppressed. Interfering tissue water and cerebrospinal fluid (CSF) signals are much stronger than myelin due to their longer T2 and abundance. By carefully optimizing the echo times a 50-fold tissue water suppression is achieved along with a 10-fold CSF suppression. For comparison 4, 5, and 32 echo filters are also designed using the same method. The SNR efficiency of these filters is very similar. The 3-echo filter design was validated by phantom scans. In addition, multislice in vivo myelin images were acquired from both a healthy volunteer and a multiple sclerosis patient. Total scan time was 5 min. A uniform T2 filter is also designed to pass all white matter species with uniform gain. The myelin-water fraction of the in vivo 3-echo data set is then measured by dividing the myelin image by the uniformly filtered image. Obtained myelin-water fractions compare well with previous work.

  View details for DOI 10.1002/mrm.20360

  View details for Web of Science ID 000226651100018

  View details for PubMedID 15678534

• Reduction of blurring in view angle tilting MRI MAGNETIC RESONANCE IN MEDICINE Butts, K., Pauly, J. M., Gold, G. E. 2005; 53 (2): 418-424

  Abstract

  Magnetic resonance imaging (MRI) in the presence of metallic objects suffers from slice-selection errors and in-plane distortions. View angle tilting (VAT) corrects for in-plane distortions by adding a gradient on the slice-select axis during readout, but can suffer from image blurring. This work demonstrates that the major source of blurring is a slice profile modulation of the data, and proposes several solutions to prevent such blurring. Multiple high-bandwidth readouts are demonstrated to reduce the blurring while improving the signal-to-noise ratio (SNR) over a single high-bandwidth readout.

  View details for DOI 10.1002/mrm.20375

  View details for Web of Science ID 000226651100020

  View details for PubMedID 15678535

• Musculoskeletal MRI at 3.0T: Initial clinical experience AMERICAN JOURNAL OF ROENTGENOLOGY Gold, G. E., Suh, B., Sawyer-Glover, A., Beaulieu, C. 2004; 183 (5): 1479-1486

  View details for Web of Science ID 000224685700050

  View details for PubMedID 15505324

• Femoral diaphyseal stress fractures: results of a systematic bone scan and magnetic resonance imaging evaluation in 25 runners PHYSICAL THERAPY IN SPORT Fredericson, M., Jang, K. U., Bergman, G., Gold, G. 2004; 5 (4): 188-193

  View details for DOI 10.1016/j.ptsp.2004.05.004

  View details for Web of Science ID 000225502900005

• Weight-bearing MRI of patellofemoral joint cartilage contact area JOURNAL OF MAGNETIC RESONANCE IMAGING Gold, G. E., Besier, T. F., Draper, C. E., Asakawa, D. S., Delp, S. L., Beaupre, G. S. 2004; 20 (3): 526-530

  Abstract

  To measure contact area of cartilage in the patellofemoral joint during weight bearing using an open MRI scanner.We developed an MR-compatible back support that allows three-dimensional imaging of the patellofemoral cartilage under physiologic weight-bearing conditions with negligible motion artifact in an open MRI scanner. To measure contact areas, we trained observers using a phantom of known area and tested intra- and interobserver variability. We measured in vivo contact areas between the patella and femoral cartilage with the knee in 30 degrees of flexion, loaded and unloaded, in six volunteers.We were able to measure the contact area of the patellofemoral cartilage with small interobserver (CV 7.0%) and intraobserver (CV 3.0%) variation. At 30 degrees of knee flexion, mean contact area increased from 400 mm2 (unloaded) to 522 mm2(loaded to 0.45 times body weight per leg).Using an open magnet and specially designed apparatus, it is possible to image the patellar cartilage during physiologic loading. Knowledge of patellar cartilage contact area is needed to assess patellofemoral stress, which may be increased in patients with patellofemoral pain syndrome.

  View details for DOI 10.1002/jmri.20146

  View details for Web of Science ID 000223522200024

  View details for PubMedID 15332263

• Musculoskeletal MRI at 3.0T: Relaxation times and image contrast AMERICAN JOURNAL OF ROENTGENOLOGY Gold, G. E., Han, E., Stainsby, J., Wright, G., Brittain, J., Beaulieu, C. 2004; 183 (2): 343-351

  Abstract

  The purpose of our study was to measure relaxation times in musculoskeletal tissues at 1.5 and 3.0 T to optimize musculoskeletal MRI methods at 3.0 T.In the knees of five healthy volunteers, we measured the T1 and T2 relaxation times of cartilage, synovial fluid, muscle, marrow, and fat at 1.5 and 3.0 T. The T1 relaxation times were measured using a spiral Look-Locker sequence with eight samples along the T1 recovery curve. The T2 relaxation times were measured using a spiral T2 preparation sequence with six echoes. Accuracy and repeatability of the T1 and T2 measurement sequences were verified in phantoms.T1 relaxation times in cartilage, muscle, synovial fluid, marrow, and subcutaneous fat at 3.0 T were consistently higher than those measured at 1.5 T. Measured T2 relaxation times were reduced at 3.0 T compared with 1.5 T. Relaxation time measurements in vivo were verified using calculated and measured signal-to-noise results. Relaxation times were used to develop a high-resolution protocol for T2-weighted imaging of the knee at 3.0 T.MRI at 3.0 T can improve resolution and speed in musculoskeletal imaging; however, interactions between field strength and relaxation times need to be considered for optimal image contrast and signal-to-noise ratio. Scanning can be performed in shorter times at 3.0 T using single-average acquisitions. Efficient higher-resolution imaging at 3.0 T can be done by increasing the TR to account for increased T1 relaxation times and acquiring thinner slices than at 1.5 T.

  View details for Web of Science ID 000222895600028

  View details for PubMedID 15269023

• Analysis of multiple-acquisition SSFP MAGNETIC RESONANCE IN MEDICINE Bangerter, N. K., Hargreaves, B. A., Vasanawala, S. S., Pauly, J. M., Gold, G. E., Nishimura, D. G. 2004; 51 (5): 1038-1047

  Abstract

  Refocused steady-state free precession (SSFP) is limited by its high sensitivity to local field variation, particularly at high field strengths or the long repetition times (TRs) necessary for high resolution. Several methods have been proposed to reduce SSFP banding artifact by combining multiple phase-cycled SSFP acquisitions, each differing in how individual signal magnitudes and phases are combined. These include maximum-intensity SSFP (MI-SSFP) and complex-sum SSFP (CS-SSFP). The reduction in SSFP banding is accompanied by a loss in signal-to-noise ratio (SNR) efficiency. In this work a general framework for analyzing banding artifact reduction, contrast, and SNR of any multiple-acquisition SSFP combination method is presented. A new sum-of-squares method is proposed, and a comparison is performed between each of the combination schemes. The sum-of-squares SSFP technique (SOS-SSFP) delivers both robust banding artifact reduction and higher SNR efficiency than other multiple-acquisition techniques, while preserving SSFP contrast.

  View details for DOI 10.1002/mrm.20052

  View details for Web of Science ID 000221239000022

  View details for PubMedID 15122688

• Steady-state diffusion-weighted imaging of in vivo knee cartilage MAGNETIC RESONANCE IN MEDICINE Miller, K. L., Hargreaves, B. A., Gold, G. E., Pauly, J. M. 2004; 51 (2): 394-398

  Abstract

  Diffusion-weighted imaging (DWI) has strong potential as a diagnostic for early cartilage damage, with clinical impact for diseases such as osteoarthritis. However, in vivo DWI of cartilage has proven difficult with conventional methods due to the short T2. This work presents a 3D steady-state DWI sequence that is able to image short-T2 species with high SNR. When combined with 2D navigator correction of motion-induced phase artifacts, this method enables high resolution in vivo DWI of cartilage. In vivo knee images in healthy subjects are presented with high SNR (SNR = 110) and submillimeter in-plane resolution (0.5 x 0.7 x 3.0 mm(3)). A method for fitting the diffusion coefficient is presented which produces fits within 10% of literature values. This method should be applicable to other short-T2 tissues, such as muscle, which are difficult to image using traditional DWI methods.

  View details for DOI 10.1002/mrm.10696

  View details for Web of Science ID 000188718600023

  View details for PubMedID 14755666

• Advanced MR imaging of the shoulder: dedicated cartilage techniques. Magnetic resonance imaging clinics of North America Gold, G. E., Reeder, S. B., Beaulieu, C. F. 2004; 12 (1): 143-?

  View details for PubMedID 15066598

• Multicoil Dixon chemical species separation with an iterative least-squares estimation method MAGNETIC RESONANCE IN MEDICINE Reeder, S. B., Wen, Z. F., Yu, H. Z., Pineda, A. R., Gold, G. E., Markl, M., Pelc, N. J. 2004; 51 (1): 35-45

  Abstract

  This work describes a new approach to multipoint Dixon fat-water separation that is amenable to pulse sequences that require short echo time (TE) increments, such as steady-state free precession (SSFP) and fast spin-echo (FSE) imaging. Using an iterative linear least-squares method that decomposes water and fat images from source images acquired at short TE increments, images with a high signal-to-noise ratio (SNR) and uniform separation of water and fat are obtained. This algorithm extends to multicoil reconstruction with minimal additional complexity. Examples of single- and multicoil fat-water decompositions are shown from source images acquired at both 1.5T and 3.0T. Examples in the knee, ankle, pelvis, abdomen, and heart are shown, using FSE, SSFP, and spoiled gradient-echo (SPGR) pulse sequences. The algorithm was applied to systems with multiple chemical species, and an example of water-fat-silicone separation is shown. An analysis of the noise performance of this method is described, and methods to improve noise performance through multicoil acquisition and field map smoothing are discussed.

  View details for Web of Science ID 000188041500007

  View details for PubMedID 14705043

• Magnetic resonance imaging findings after rectus femoris transfer surgery 3rd Special Scientific Session of the International-Skeletal-Society Gold, G. E., Asakawa, D. S., Blemker, S. S., Delp, S. L. SPRINGER. 2004: 34–40

  Abstract

  We describe the magnetic resonance (MR) imaging appearance of the knee flexor and extensor tendons after bilateral rectus femoris transfer and hamstring lengthening surgery in five patients (10 limbs) with cerebral palsy. Three-dimensional models of the path of the transferred tendon were constructed in all cases. MR images of the transferred and lengthened tendons were examined and compared with images from ten non-surgical subjects. The models showed that the path of the transferred rectus femoris tendon had a marked angular deviation near the transfer site in all cases. MR imaging demonstrated irregular areas of low signal intensity near the transferred rectus femoris and around the hamstrings in all subjects. Eight of the ten post-surgical limbs showed evidence of fluid near or around the transferred or lengthened tendons. This was not observed in the non-surgical subjects. Thus, MR imaging of patients with cerebral palsy after rectus femoris transfer and hamstring-lengthening surgery shows evidence of signal intensity and contour changes, even several years after surgery.

  View details for DOI 10.1007/s00256-003-0702-5

  View details for Web of Science ID 000187505400005

  View details for PubMedID 14605768

• Real-time imaging of skeletal muscle velocity 9th Annual Meeting of the ISMRM Asakawa, D. S., Nayak, K. S., Blemker, S. S., Delp, S. L., Pauly, J. M., Nishimura, D. G., Gold, G. E. JOHN WILEY & SONS INC. 2003: 734–39

  Abstract

  To test the feasibility of using real-time phase contrast (PC) magnetic resonance imaging (MRI) to track velocities (1-20 cm/second) of skeletal muscle motion.To do this we modified a fast real-time spiral PC pulse sequence to accommodate through-plane velocity encoding in the range of -20 to +20 cm/second. We successfully imaged motion of the biceps brachii and triceps brachii muscles during elbow flexion and extension in seven unimpaired adult subjects using real-time PC MRI.The velocity data demonstrate that the biceps brachii and the triceps brachii, antagonistic muscles, move in opposite directions during elbow flexion and extension with velocity values in the muscle tissue ranging from -10 to +10 cm/second.With further development, real-time PC MRI may provide a means to analyze muscle function in individuals with neurologic or movement disorders who cannot actively complete the repeated motions required for dynamic MRI techniques, such as cine PC MRI, that are more commonly used in musculoskeletal biomechanics applications.

  View details for DOI 10.1002/jmri.10422

  View details for Web of Science ID 000186844200013

  View details for PubMedID 14635159

• Dynamic and functional imaging of the musculoskeletal system. Seminars in musculoskeletal radiology Gold, G. E. 2003; 7 (4): 245-248

  Abstract

  Conventional magnetic resonance imaging (MRI) examination of the musculoskeletal system is limited to static evaluation of muscle, spine, and joint morphology. However, using the variety of contrast mechanisms available with MRI, it is possible to obtain functional and biomechanical data about the musculoskeletal system. The function of joints and muscles are for motion and weight bearing, so pathology that only occurs during activity can be missed on static MRI examination. Similarly, important information about muscle biomechanics, muscle energetics, and joint function can be obtained with unique MRI contrast such as T(2)-mapping, spectroscopy, blood-oxygenation-level-dependent (BOLD) imaging, and molecular imaging. These new techniques hold the promise for a more complete and useful joint examination.

  View details for PubMedID 14735424

• What's new in cartilage? Radiographics Gold, G. E., McCauley, T. R., Gray, M. L., Disler, D. G. 2003; 23 (5): 1227-1242

  Abstract

  Magnetic resonance (MR) imaging of articular cartilage is important in evaluation of new surgical and pharmacologic treatments for cartilage damage. Many techniques exist for MR imaging of articular cartilage. Standard techniques for morphologic imaging of cartilage include fast spin-echo and spoiled gradient-echo imaging. These methods provide high-resolution morphologic images of cartilage but are time-consuming in the clinical setting. New methods for faster or higher-resolution morphologic imaging include techniques based on steady-state free precession imaging. These fast techniques will allow detailed evaluation of cartilage in the routine clinical setting. There are also several MR imaging methods that may provide information about the structure and physiology of cartilage. Physiologic imaging may allow detailed evaluation of the glycosaminoglycan matrix or collagen network of articular cartilage and may be the most sensitive method for detection of early changes. With the development of new therapies for osteoarthritis and cartilage injury, MR imaging of articular cartilage is of increasing clinical importance. MR imaging will play an important role in evaluation of the effectiveness of these therapies.

  View details for PubMedID 14518449

• Special focus session - What's new in cartilage? 88th Scientific Assembly and Annual Meeting of the Radiological-Society-of-North-America Gold, G. E., McCauley, T. R., Gray, M. L., Disler, D. G. RADIOLOGICAL SOC NORTH AMERICA. 2003: 1227–42

  View details for Web of Science ID 000185333900014

• Comparison of new sequences for high-resolution cartilage imaging MAGNETIC RESONANCE IN MEDICINE Hargreaves, B. A., Gold, G. E., Beaulieu, C. F., Vasanawala, S. S., Nishimura, D. G., Pauly, J. M. 2003; 49 (4): 700-709

  Abstract

  The high prevalence of osteoarthritis continues to demand improved accuracy in detecting cartilage injury and monitoring its response to different treatments. MRI is the most accurate noninvasive method of diagnosing cartilage lesions. However, MR imaging of cartilage is limited by scan time, signal-to-noise ratio (SNR), and image contrast. Recently, there has been renewed interest in SNR-efficient imaging sequences for imaging cartilage, including various forms of steady-state free-precession as well as driven-equilibrium imaging. This work compares several of these sequences with existing methods, both theoretically and in normal volunteers. Results show that the new steady-state methods increase SNR-efficiency by as much as 30% and improve cartilage-synovial fluid contrast by a factor of three. Additionally, these methods markedly decrease minimum scan times, while providing 3D coverage without the characteristic blurring seen in fast spin-echo images.

  View details for DOI 10.1002/mrm.10424

  View details for Web of Science ID 000182007200013

  View details for PubMedID 12652541

• Interactive and interventional sports medicine imaging. Topics in magnetic resonance imaging Beaulieu, C. F., Gold, G. E. 2003; 14 (2): 115-130

  Abstract

  The concepts and clinical potential of interactive magnetic resonance imaging (MRI) in which an examiner manipulates the joint of interest during MRI, and of interventional sports medicine imaging in which radiological guidance is used for targeted therapy of injuries and masses are described. As illustrated by a series of clinical cases, we believe that with further development, interactive MRI will play an important role in the comprehensive evaluation of patients with shoulder pain or dysfunction as well as other joint derangements. Interventional sports medicine takes advantage of the increasingly sophisticated diagnostic value of MRI and the radiologist's ability to use imaging to guide percutaneous therapy. We review our recent experience treating a wide variety of disorders such as cysts, hematomas, and inflammatory disorders, focusing on techniques utilizing ultrasound and MR guidance.

  View details for PubMedID 12777885

• Rapid MR imaging of articular cartilage with steady-state free precession and multipoint fat-water separation. AJR. American journal of roentgenology Reeder, S. B., Pelc, N. J., Alley, M. T., Gold, G. E. 2003; 180 (2): 357-362

  Abstract

  To obtain high-quality high-resolution images of articular cartilage with reduced imaging time, we combined a novel technique of generalized multipoint fat-water separation with three-dimensional (3D) steady-state free precession (SSFP) imaging.The cartilage of 10 knees in five healthy volunteers was imaged with 3D SSFP imaging and a multipoint fat-water separation method capable of separating fat and water with short TE increments. Fat-saturated 3D spoiled gradient-echo (SPGR) images were obtained for comparison.High-quality images of the knee with excellent fat-water separation were obtained with 3D SSFP imaging. Total imaging time required was 58% less than that required for 3D SPGR imaging with a comparable cartilage signal-to-noise ratio and spatial resolution. Unlike 3D SPGR images, 3D SSFP images exhibited bright synovial fluid, providing a potential arthrographic effect.High-quality high-resolution images of articular cartilage with improved fat-water separation, bright synovial fluid, and markedly reduced acquisition times can be obtained with 3D SSFP imaging combined with a fat-water separation technique.

  View details for PubMedID 12540434

• Rapid imaging cartilage with precession and of articular steady-state free multipoint fat water separation AMERICAN JOURNAL OF ROENTGENOLOGY Reeder, S. B., Pelc, N. J., Alley, M. T., Gold, G. E. 2003; 180 (2): 357-362

  Abstract

  To obtain high-quality high-resolution images of articular cartilage with reduced imaging time, we combined a novel technique of generalized multipoint fat-water separation with three-dimensional (3D) steady-state free precession (SSFP) imaging.The cartilage of 10 knees in five healthy volunteers was imaged with 3D SSFP imaging and a multipoint fat-water separation method capable of separating fat and water with short TE increments. Fat-saturated 3D spoiled gradient-echo (SPGR) images were obtained for comparison.High-quality images of the knee with excellent fat-water separation were obtained with 3D SSFP imaging. Total imaging time required was 58% less than that required for 3D SPGR imaging with a comparable cartilage signal-to-noise ratio and spatial resolution. Unlike 3D SPGR images, 3D SSFP images exhibited bright synovial fluid, providing a potential arthrographic effect.High-quality high-resolution images of articular cartilage with improved fat-water separation, bright synovial fluid, and markedly reduced acquisition times can be obtained with 3D SSFP imaging combined with a fat-water separation technique.

  View details for Web of Science ID 000180753200014

• Protocols in sports magnetic resonance imaging. Topics in magnetic resonance imaging Gold, G. E., Hargreaves, B. A., Beaulieu, C. F. 2003; 14 (1): 3-23

  Abstract

  Magnetic resonance imaging, with its multiplanar imaging capability and superior soft-tissue contrast, has become the preferred method for imaging sports-related injuries. Advances in gradient technology, receiver coils, and imaging software have allowed the imaging of the injured athlete to take place quickly and at high resolution. Understanding the tissues being imaged, the underlying anatomy, and the capabilities of today's scanners is crucial to the design of intelligent and efficient protocols.

  View details for PubMedID 12606866

• Multi-point "Dixon" fat-water separation and steady-state free precession 88th Scientific Assembly and Annual Meeting of the Radiological-Society-of-North-America Reeder, S. B., Wen, Z., Gold, G. E., Alley, M. T., Markl, M., Pelc, N. J. RADIOLOGICAL SOC NORTH AMERICA. 2002: 313–313

  View details for Web of Science ID 000178825100793

• MR imaging of knee cartilage with FEMR SKELETAL RADIOLOGY Vasnawala, S. S., Pauly, J. M., Nishimura, D. G., Gold, G. E. 2002; 31 (10): 574-580

  Abstract

  Fluctuating equilibrium magnetic resonance (FEMR) is a rapid three-dimensional (3D) imaging sequence with high signal-to-noise ratio (SNR). FEMR may be useful for detecting cartilage defects in the knee. At 1.5 T, FEMR uses a TR with odd multiples of 2.2 ms for fat/water separation. With a TR of 6.6 ms, high-resolution 3D imaging of cartilage is possible.The knees of 10 volunteers and two patients were imaged on a GE Signa 1.5 T scanner using an extremity coil. Scans were preceded by a shimming sequence optimizing linear terms. Subjects were imaged with FEMR, proton-density fast spin-echo (PD-FSE), T2-weighted fast spin-echo (T2-FSE), and 3D fat-suppressed spoiled-gradient-recalled echo (3D-SPGR).SNR and contrast-to-noise efficiency measurements for cartilage using FEMR were superior to those using PD-FSE, T2-FSE, and 3D-FS-SPGR. FSE images showed bright synovial fluid with limited cartilage detail. 3D-SPGR had comparable resolution to FEMR but suboptimal cartilage/fluid contrast and longer scan times (8 min versus 2 min). Cartilage surface detail, outlined by bright synovial fluid, was best seen on the FEMR images.FEMR obtains high-resolution 3D images of the entire knee in 2 min with excellent cartilage/fluid contrast. FEMR is sensitive to field inhomogeneity and requires shimming. Surface defects are outlined by bright synovial fluid, and cartilage has higher signal-to-noise efficiency compared with PD-FSE, T2-FSE, and 3D-SPGR techniques.

  View details for DOI 10.1007/s00256-002-0562-4

  View details for Web of Science ID 000178773000003

  View details for PubMedID 12324826

• In vivo motion of the rectus femoris muscle after tendon transfer surgery JOURNAL OF BIOMECHANICS Asakawa, D. S., Blemker, S. S., Gold, G. E., Delp, S. L. 2002; 35 (8): 1029-1037

  Abstract

  Rectus femoris transfer surgery is performed to convert the rectus femoris muscle from a knee extensor to a knee flexor. In this surgery, the distal tendon of the rectus femoris is detached from the patella and reattached to one of the knee flexor tendons. The outcomes of this procedure are variable, and it is not known if the surgery successfully converts the muscle to a knee flexor. We measured the motion of muscle tissue within the rectus femoris and vastus intermedius during knee extension in 10 unimpaired control subjects (10 limbs) and 6 subjects (10 limbs) after rectus femoris transfer using cine phase-contrast magnetic resonance imaging. Displacements of the vastus intermedius during knee extension were similar between control and tendon transfer subjects. In the control subjects, the rectus femoris muscle consistently moved in the direction of the knee extensors and displaced more than the vastus intermedius. The rectus femoris also moved in the direction of the knee extensors in the tendon transfer subjects; however, the transferred rectus femoris displaced less than the vastus intermedius. These results suggest that the rectus femoris is not converted to a knee flexor after its distal tendon is transferred to the posterior side of the knee, but its capacity for knee extension is diminished by the surgery.

  View details for Web of Science ID 000177318000003

  View details for PubMedID 12126662

• Short echo time MR spectroscopic imaging of the lung parenchyma JOURNAL OF MAGNETIC RESONANCE IMAGING Gold, G. E., Pauly, J. M., Leung, A. N., Block, W. F., Meyer, C. H., Sze, R., Macovski, A., Stark, P. 2002; 15 (6): 679-684

  Abstract

  To perform short echo time MR spectroscopic imaging of the lung parenchyma on normal volunteers.A short echo time projection-reconstruction spectroscopic imaging sequence was implemented on a commercial 1.5T whole body MRI scanner. Images and spectra of the lung parenchyma were obtained from five normal volunteers. Breath-held spectroscopic imaging was also performed.Spectroscopic imaging of short-T2* species allows visualization of different anatomic structures based upon their frequency shifts. A characteristic peak from the parenchyma was seen at three ppm from water frequency.Short echo time MR spectroscopic imaging of the lung parenchyma was demonstrated in normal volunteers. This method may improve proton imaging of the lungs and add specificity to the diagnosis of pulmonary disease.

  View details for DOI 10.1002/jmri.10113

  View details for Web of Science ID 000175918300008

  View details for PubMedID 12112518

• Handheld access to radiology teaching files: An automated system for format conversion and content creation Medical Imaging 2002 Conference Raman, R., Raman, L., Raman, B., Gold, G., Beaulieu, C. F. SPIE-INT SOC OPTICAL ENGINEERING. 2002: 249–259

  View details for Web of Science ID 000176733900029

• Future of MR imaging of articular cartilage. Seminars in musculoskeletal radiology Gold, G. E., Beaulieu, C. F. 2001; 5 (4): 313-327

  Abstract

  Osteoarthritis, based on either cartilage injury or degeneration, is a leading cause of disability in the United States. Over the last several decades, much progress has been made in understanding cartilage injury and repair. Magnetic resonance (MR) imaging, with its unique ability to noninvasively image and characterize soft tissue, has shown promise in assessment of cartilage integrity. In addition to standard MR imaging methods, MR imaging contrast mechanisms under development may reveal detailed information regarding the physiology and morphology of cartilage. MR imaging will play a crucial role in assessing the success or failure of therapies addressing cartilage injury and degeneration.

  View details for PubMedID 11745048

• Magnetic resonance imaging of articular cartilage CLINICAL ORTHOPAEDICS AND RELATED RESEARCH Recht, M., Bobic, V., Burstein, D., Disler, D., Gold, G., Gray, M., Kramer, J., Lang, P., McCauley, T., Winalski, C. 2001: S379-S396

  Abstract

  Magnetic resonance imaging is the optimal modality for assessing articular cartilage because of superior soft tissue contrast, direct visualization of articular cartilage, and multiplanar capability. Despite these advantages, there has been disagreement as to the efficacy of magnetic resonance imaging of articular cartilage. The reason for this controversy is multifactorial but in part is attributable to the lack of the use of optimized pulse sequences for articular cartilage. The current authors will review the current state of the art of magnetic resonance imaging of articular cartilage and cartilage repair procedures, discuss future new directions in imaging strategies and methods being developed to measure cartilage thickness and volume measurements, and propose a magnetic resonance imaging protocol to evaluate cartilage that is achievable on most magnetic resonance scanners, vendor independent, practical (time and cost efficient), and accepted and used by a majority of musculoskeletal radiologists.

  View details for Web of Science ID 000171624500035

  View details for PubMedID 11603721

• Dynamic MR imaging and stress testing in glenohumeral instability: Comparison with normal shoulders and clinical/surgical findings JOURNAL OF MAGNETIC RESONANCE IMAGING Hodge, D. K., Beaulieu, C. F., Thabit, G. H., Gold, G. E., Bergman, A. G., Butts, R. K., Dillingham, M. F., Herfkens, R. J. 2001; 13 (5): 748-756

  Abstract

  Our objectives were to test the hypotheses that: 1) during shoulder motion, glenohumeral alignment differs between asymptomatic shoulders and those with symptomatic instability; 2) during magnetic resonance (MR)-monitored physical exam or stress testing, glenohumeral alignment differs between asymptomatic shoulders and those with instability; and 3) glenohumeral translation during MR stress testing correlates with findings of shoulder instability by clinical exam and exam under anesthesia (EUA). Using an open-configuration 0.5 T MR imaging (MRI) system, we studied symptomatic shoulders in 11 subjects and compared them to their contralateral asymptomatic shoulders. Each shoulder was studied during abduction/adduction and internal/external rotation to determine the humeral head position on the glenoid. An examiner also performed the MR stress test on each shoulder by applying manual force on the humeral head during imaging. All shoulders were assigned an instability grade from the MR stress test, and this grade was correlated with: 1) clinical exam grade assigned during preoperative assessment by an orthopedic surgeon and 2) intraoperative instability grade by EUA immediately preceding arthroscopy. With dynamic abduction and internal/external rotation, the humeral head remained centered on the glenoid in 9 of 11 shoulders, but in two subjects there were dramatic demonstrations of subluxation. With stress testing, a trend toward more joint laxity was demonstrated in symptomatic than in asymptomatic joints (P = 0.11). MR grading of instability correlated directly with clinical grading in six cases and underestimated the degree of instability relative to clinical exam in the other cases. MR instability grading systematically underestimated instability compared with EUA in 7 of the 10 cases that underwent surgical repair. We concluded that dynamic MR evaluation of glenohumeral alignment did not demonstrate abnormalities in symptomatic shoulders in 8 of 10 patients, whereas 2 patients showed dramatic findings of subluxation. Manual stress testing during dynamic MR examination showed a strong correlation with clinical instability grading. Dynamic shoulder MR examination during stress testing could, with further validation, become a useful adjunct to shoulder instability evaluations. J. Magn. Reson. Imaging 2001;13:748-756.

  View details for Web of Science ID 000171296300012

  View details for PubMedID 11329197

• Plantar fasciitis and fascial rupture: MR imaging findings in 26 patients supplemented with anatomic data in cadavers 85th Annual Meeting and Scientific Assembly of the Radiological-Society-of-North-America (RSNA) Theodorou, D. J., Theodorou, S. J., Kakitsubata, Y., Lektrakul, N., Gold, G. E., Roger, B., Resnick, D. RADIOLOGICAL SOC NORTH AMERICA. 2000: S181–S197

  Abstract

  Understanding of the normal anatomy of the plantar aponeurosis (PA) and familiarity with pathologic conditions are required for an accurate evaluation of the patient with subcalcaneal heel pain. In this study, we evaluated the diagnostic capabilities of magnetic resonance (MR) imaging in the assessment of the PA with close anatomic correlation. Herein, we describe the MR imaging features of plantar fasciitis and fascial rupture in 26 patients. High-spatial-resolution MR imaging was performed in four cadaveric feet, and a prescribed imaging plane was used for depiction of the peroneal component of the PA. MR imaging delineated the anatomy of the PA and perifascial soft tissues. The peroneal component was best visualized in prescribed sagittal oblique images. Perifascial edema was the most common finding of plantar fasciitis, and it was remarkable in those cases with acute fascial rupture. MR imaging reliably delineated the anatomy of the PA and may allow precise localization and definition of the extent of involvement in disease processes.

  View details for Web of Science ID 000171512400013

  View details for PubMedID 11046170

• Motion correction and lipid suppression for H-1 magnetic resonance spectroscopy Scientific Meeting of the International-Society-for-Magnetic-Resonance-in-Medicine Star-Lack, J. M., Adalsteinsson, E., Gold, G. E., Ikeda, D. M., Spielman, D. M. JOHN WILEY & SONS INC. 2000: 325–30

  Abstract

  Spectral/spatial spin-echo pulses with asymmetric excitation profiles were incorporated into a PRESS-based localization sequence to provide lipid suppression while retaining a sufficient amount of water to allow for correction of motion-induced shot-to-shot phase variations. 1H magnetic resonance spectroscopy data were acquired at 1.5 Tesla from a motion phantom and in vivo from the human liver, kidney, and breast. The results demonstrated that lipids in the chemical shift stopband were completely suppressed and that full metabolite signal intensity was maintained after implementation of a regularization algorithm based on phasing the residual water signal. Liver and kidney spectra contained a large resonance at 3.2 ppm that was ascribed to trimethylammonium moieties (betaine plus choline) and a weaker signal at 3.7 ppm that may result from glycogen. A breast spectrum from a histologically proven invasive ductal carcinoma displayed a highly elevated choline signal (3.2 ppm) relative to that from a normal volunteer.

  View details for Web of Science ID 000085559100001

  View details for PubMedID 10725872

• Dynamic evaluation of shoulder instability using open MR imaging 14th International Congress and Exhibition on Computer Assisted Radiology and Surgery (CARS 2000) Beaulieu, C. F., Dillingham, M. F., Hodge, D. K., Butts, K., Gold, G. E., Thabit, G. H., Ladd, A. L., Bergman, A. G. ELSEVIER SCIENCE BV. 2000: 309–314

  View details for Web of Science ID 000165685600052

• MR imaging of articular cartilage using driven equilibrium Scientific Meeting of the International-Society-for-Magnetic-Resonance-in-Medicine Hargreaves, B. A., Gold, G. E., Lang, P. K., Conolly, S. M., Pauly, J. M., Bergman, G., Vandevenne, J., Nishimura, D. G. JOHN WILEY & SONS INC. 1999: 695–703

  Abstract

  The high incidence of osteoarthritis and the recent advent of several new surgical and non-surgical treatment approaches have motivated the development of quantitative techniques to assess cartilage loss. Although magnetic resonance (MR) imaging is the most accurate non-invasive diagnostic modality for evaluating articular cartilage, improvements in spatial resolution, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) would be valuable. Cartilage presents an imaging challenge due to its short T(2) relaxation time and its low water content compared with surrounding materials. Current methods sacrifice cartilage signal brightness for contrast between cartilage and surrounding tissue such as bone, bone marrow, and joint fluid. A new technique for imaging articular cartilage uses driven equilibrium Fourier transform (DEFT), a method of enhancing signal strength without waiting for full T(1) recovery. Compared with other methods, DEFT imaging provides a good combination of bright cartilage and high contrast between cartilage and surrounding tissue. Both theoretical predictions and images show that DEFT is a valuable method for imaging articular cartilage when compared with spoiled gradient-recalled acquisition in the steady state (SPGR) or fast spin echo (FSE). The cartilage SNR for DEFT is as high as that of either FSE or SPGR, while the cartilage-synovial fluid CNR of DEFT is as much as four times greater than that of FSE or SPGR. Implemented as a three-dimensional sequence, DEFT can achieve coverage comparable to that of other sequences in a similar scan time. Magn Reson Med 42:695-703, 1999.

  View details for Web of Science ID 000082944400011

  View details for PubMedID 10502758

• High-resolution three-dimensional in vivo imaging of atherosclerotic plaque MAGNETIC RESONANCE IN MEDICINE Luk-Pat, G. T., Gold, G. E., Olcott, E. W., Hu, B. S., Nishimura, D. G. 1999; 42 (4): 762-771

  Abstract

  The internal structure of atherosclerotic-plaque lesions may be a useful predictor of which lesions will rupture and cause sudden events such as heart attack or stroke. With lipid and flow suppression, we obtained high-resolution, three-dimensional (3D) images of atherosclerotic plaque in vivo that show the cap thickness and core size of the lesions. 3D GRASE was used because it provides flexible T(2) contrast and good resistance to off-resonance artifacts. While 2D RARE has similar properties, its resolution in the slice-select direction, which is important because of the irregular geometry of atherosclerotic lesions, is limited by achievable slice-excitation profiles. Also, 2D imaging generally achieves lower SNR than 3D imaging because, for SNR purposes, 3D image data is averaged over all the slices of a corresponding multislice 2D dataset. Although 3D RARE has many of the advantages of 3D GRASE, it requires a longer scan time because it uses more refocusing pulses to acquire the same amount of data. Finally, cardiac gating is an important part of our imaging sequence, but can make the imaging time quite long. To obtain reasonable scan times, a 2D excitation pulse was used to restrict the field of view. Magn Reson Med 42:762-771, 1999.

  View details for Web of Science ID 000082944400019

  View details for PubMedID 10502766

• Ultra-short echo-time 2D time-of-flight MR angiography using a half-pulse excitation MAGNETIC RESONANCE IN MEDICINE Nielsen, H. T., Gold, G. E., Olcott, E. W., Pauly, J. M., Nishimura, D. G. 1999; 41 (3): 591-599

  Abstract

  Flow-related artifacts remain a significant concern for magnetic resonance (MR) angiography because their appearance in angiograms adversely impacts accuracy in evaluation of arterial stenoses. In this paper, a half-pulse excitation scheme for improved two-dimensional time-of-flight (2D TOF) angiography is described. The proposed method eliminates the need for gradient moment nulling (of all orders), providing significant reductions in spin dephasing and consequent artifactual signal loss. Furthermore, because the post-excitation refocusing and flow compensation gradients are obviated, the achievable echo time is dramatically shortened. The half-pulse excitation is employed in conjunction with a fast radial-line acquisition, allowing ultra-short echo times on the order of 250-300 microsec. Radial-line acquisition methods also provide additional benefits for flow imaging: effective mitigation of pulsatile flow artifacts, full k-space coverage, and decreased scan times. The half-pulse excitation/radial-line sequence demonstrated improved performance in initial clinical evaluations of the carotid bifurcation when compared with a conventional 2D TOF sequence.

  View details for Web of Science ID 000079317800023

  View details for PubMedID 10204884

• Magnetic resonance imaging of knee cartilage repair. Topics in magnetic resonance imaging Gold, G. E., Bergman, A. G., Pauly, J. M., Lang, P., Butts, R. K., Beaulieu, C. F., Hargreaves, B., Frank, L., Boutin, R. D., Macovski, A., Resnick, D. 1998; 9 (6): 377-392

  Abstract

  Cartilage injury resulting in osteoarthritis is a frequent cause of disability in young people. Osteoarthritis, based on either cartilage injury or degeneration, is a leading cause of disability in the United States. Over the last several decades, much progress has been made in understanding cartilage injury and repair. Magnetic resonance (MR) imaging, with its unique ability to noninvasively image and characterize soft tissue, has shown promise in assessment of cartilage integrity. In addition to standard MR imaging methods, MR imaging contrast mechanisms under development may reveal detailed information regarding the physiology and morphology of cartilage. MR imaging will play a crucial role in assessing the success or failure of therapies for cartilage injury and degeneration.

  View details for PubMedID 9894740

• MR imaging of articular cartilage of the knee: New methods using ultrashort TEs AMERICAN JOURNAL OF ROENTGENOLOGY Gold, G. E., Thedens, D., Pauly, J. M., Fechner, K. P., Bergman, G., Beaulieu, C. F., Macovski, A. 1998; 170 (5): 1223-1226

  View details for Web of Science ID 000073257300016

  View details for PubMedID 9574589

• Three-dimensional flow-independent peripheral angiography MAGNETIC RESONANCE IN MEDICINE Brittain, J. H., Olcott, E. W., Szuba, A., Gold, G. E., Wright, G. A., Irarrazaval, P., Nishimura, D. G. 1997; 38 (3): 343-354

  Abstract

  A magnetization-prepared sequence, T2-Prep-IR, exploits T1, T2, and chemical shift differences to suppress background tissues relative to arterial blood. The resulting flow-independent angiograms depict vessels with any orientation and flow velocity. No extrinsic contrast agent is required. Muscle is the dominant source of background signal in normal volunteers. However, long-T2 deep venous blood and nonvascular fluids such as edema also contribute background signal in some patients. Three sets of imaging parameters are described to address patient-specific contrast requirements. A rapid, spiral-based, three-dimensional readout is utilized to generate high-resolution angiograms of the lower extremities. Comparisons with x-ray angiography and two-dimensional time-of-flight angiography indicate that this flow-independent technique has unique capabilities to accurately depict stenoses and to visualize slow flow and in-plane vessels.

  View details for Web of Science ID A1997XW16200001

  View details for PubMedID 9339435

• MR SPECTROSCOPIC IMAGING OF COLLAGEN - TENDONS AND KNEE MENISCI MAGNETIC RESONANCE IN MEDICINE Gold, G. E., Pauly, J. M., Macovski, A., Herfkens, R. J. 1995; 34 (5): 647-654

  Abstract

  Water molecules associated with collagen have short transverse (T2) relaxation times. Projection-reconstruction techniques are able to achieve an echo time (TE) much shorter than conventional techniques, allowing imaging of tissues with T2 < 5 ms. Using these techniques, a conventional 1.5-T MRI human imaging system can directly image collagen-associated water from knee menisci and tendons in normal volunteers and patients. Long-T2 suppression improves the contrast between these structures and the surrounding tissue with long-T2 relaxation times. Spectroscopic imaging provides improved lipid/water registration and information about chemical composition and relaxation times. Direct imaging of tendons and menisci may provide more information about these structures and provide a new way to assess both injury and repair.

  View details for Web of Science ID A1995TD42800001

  View details for PubMedID 8544684

• CHARACTERIZATION OF ATHEROSCLEROSIS WITH A 1.5-T IMAGING-SYSTEM JMRI-JOURNAL OF MAGNETIC RESONANCE IMAGING Gold, G. E., Pauly, J. M., Glover, G. H., Moretto, J. C., Macovski, A., Herfkens, R. J. 1993; 3 (2): 399-407

  Abstract

  It is shown that a conventional 1.5-T magnetic resonance (MR) imaging system can help characterize some of the key components of atherosclerotic plaque ex vivo. Fresh human aorta with atheromata was suspended in solutions of agarose and manganese chloride and heated to body temperature. The specimens were imaged with modified Dixon and projection-reconstruction imaging sequences. The specimens were then examined histologically to obtain direct correlation between images, spectra, and histologic characteristics. The results show that vessel wall and plaque components can be identified by means of their MR characteristics and correlated with their histologic appearance. The authors were able to identify normal vessel wall components, such as adventitial lipids and smooth muscle. They were also able to identify and localize plaque components such as fibrous tissue, calcification, lipids, and possible areas of hemorrhage and hemosiderin deposition.

  View details for Web of Science ID A1993KQ88100013

  View details for PubMedID 8448403

• GUARANTEEING REAL-TIME RESPONSE WITH LIMITED RESOURCES ARTIFICIAL INTELLIGENCE IN MEDICINE Ash, D., Gold, G., Seiver, A., HAYESROTH, B. 1993; 5 (1): 49-66

  Abstract

  Unanticipated problems detected by patient-monitoring systems may sometimes require real-time response in order to provide high-quality care and avoid catastrophic outcomes. In this paper, we present an approach for guaranteeing a response to such events by a monitoring agent even in situations where we have limited problem-solving resources. We show that an action-based hierarchy can accomplish this goal. We also analyze the performance of this hierarchy under varying resource availability and discuss decision-theoretic approaches to enable us to best structure such a hierarchy. We also describe an implementation of these ideas, called ReAct, in the BB1 architecture. All the ideas are illustrated with examples from the surgical intensive care unit (SICU).

  View details for Web of Science ID A1993KM93300004

  View details for PubMedID 8358486