Bio

Clinical Focus


  • Diagnostic Radiology
  • Radiology

Academic Appointments


Administrative Appointments


  • Associate Chair for Clinical Technology, Department of Radiology, Stanford University (2005 - Present)
  • Director of MRI, Department of Radiology, Stanford University (1990 - Present)
  • Director of Destination Digital (PACS–digital imaging transfer), Department of Radiology, Stanford University (2001 - Present)
  • Co-director of PET/CT, Department of Radiology, Stanford University (2002 - 2004)

Honors & Awards


  • Lauterbur Award, Society of Computed Body Tomography and MR ('01,02,03,04, 2005,2009)
  • Fellow, International Society of Magnetic Resonance in Medicine (2001)
  • President, International Society of Magnetic Resonance in Medicine (1998-1999)
  • Chair, Safety Committee, International Society of Magnetic Resonance in Medicine (1996-1997)

Professional Education


  • Medical Education:LOYOLA UNIVERSITY CHICAGO Marcella Niehoff School of Nursing (1974) IL
  • Fellowship:UCSF Medical Center (1980) CA
  • Fellowship:UCSF Medical Center (1979) CA
  • Board Certification: Diagnostic Radiology, American Board of Radiology (1979)
  • Board Certification: Nuclear Radiology, American Board of Radiology (1980)
  • Residency:UCSF Medical Center (1978) CA
  • Residency:Loyola University Medical Center (1976) IL
  • None, Creighton University, Chemistry
  • M.D., Loyola-Stritch SOM, Medicine (1974)
  • Residency, Loyola-Stritch, Internal Medicine (1976)
  • Residency, UCSF, Radiology (1978)
  • Research Fellowship, UCSF, Nuclear Medicine (1979)

Community and International Work


  • Multiple Committees

    Partnering Organization(s)

    American College of Radiology

    Populations Served

    Radiologists

    Location

    International

    Ongoing Project

    Yes

    Opportunities for Student Involvement

    No

Research & Scholarship

Current Research and Scholarly Interests


Imaging of cardiovascular diseases with CT, magnetic resonance imaging and spectroscopy

Clinical Trials


  • Evaluating Sunitinib Therapy in Renal Cell Carcinoma Using F-18 FDG PET/CT and DCE MRI Not Recruiting

    To learn whether FDG PET/CT and DCE MRI are better predictors of response to therapy than the current standard of care (CT or MRI).

    Stanford is currently not accepting patients for this trial. For more information, please contact Andrew Quon, (650) 736 - 1369.

    View full details

  • Cervical Nodal Mets in Squamous Cell Carcinoma of H&N - MRI, FDG-PET, & Histopathologic Correlation Not Recruiting

    The purpose of this study is to determine the value of novel non-invasive medical imaging methods for detecting the spread of head and neck squamous cell carcinoma to the lymph nodes in the neck by comparing their results to findings at the time of surgery.

    Stanford is currently not accepting patients for this trial. For more information, please contact Quynh-Thu Le, (650) 498 - 6184.

    View full details

  • Magnetic Resonance Imaging of Breast Cancer Recruiting

    To compare magnetic resonance imaging (MRI) with more well established diagnostic imaging techniques to determine which method best finds and defines breast cancer.

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  • PET/CT and Whole-Body MRI for Detection of Skeletal and Soft Tissue Metastases Recruiting

    Fluorine-18 Fluorodeoxyglucose (F-18 FDG) PET/CT is established as a powerful imaging tool for cancer detection and monitoring response to therapy. However, not all cancers are identified reliably due to variable rates of glucose metabolism. Whole-body MRI emerges currently as an excellent modality for morphological characterization of soft tissue and skeletal lesions. Sodium Fluorine-18 (F-18) was used in the 1970's for bone scanning and can be used as a skeletal tracer in current PET/CT scanners. The direct comparison of F-18/F-18 FDG PET/CT and whole-body MRI for skeletal metastases detection was not attempted to date. However, such an approach has the potential to improve cancer diagnosis, staging, prognosis, and therapy monitoring. The combination of these technologies may also allow for improved screening or earlier cancer detection. We will attempt a pilot study with 10 patients to acquire the preliminary results needed to proceed with additional 90 subjects.

    View full details

Teaching

2013-14 Courses


Publications

Journal Articles


  • Respiratory-Induced 3D Deformations of the Renal Arteries Quantified With Geometric Modeling During Inspiration and Expiration Breath-Holds of Magnetic Resonance Angiography JOURNAL OF MAGNETIC RESONANCE IMAGING Suh, G., Choi, G., Draney, M. T., Herfkens, R. J., Dalman, R. L., Cheng, C. P. 2013; 38 (6): 1325-1332

    Abstract

    PURPOSE: To quantify renal artery deformation due to respiration using magnetic resonance (MR) image-based geometric analysis. MATERIALS AND METHODS: Five males were imaged with contrast-enhanced MR angiography during inspiratory and expiratory breath-holds. From 3D models of the abdominal aorta, left and right renal arteries (LRA and RRA), we quantified branching angle, curvature, peak curve angle, axial length, and locations of branch points. RESULTS: With expiration, maximum curvature changes were 0.054 ± 0.025 mm(-1) (P < 0.01), and curve angle at the most proximal curvature peak increased by 8.0 ± 4.5° (P < 0.05) in the LRA. Changes in maximum curvature and curve angles were not significant in the RRA. The first renal bifurcation point translated superiorly and posteriorly by 9.7 ± 3.6 mm (P < 0.005) and 3.5 ± 2.1 mm (P < 0.05), respectively, in the LRA, and 10.8 ± 6.1 mm (P < 0.05) and 3.6 ± 2.5 mm (P < 0.05), respectively, in the RRA. Changes in branching angle, axial length, and renal ostia locations were not significant. CONCLUSION: The LRA and RRA deformed and translated significantly. Greater deformation of the LRA as compared to the RRA may be due to asymmetric anatomy and mechanical support by the inferior vena cava. The presented methodology can extend to quantification of deformation of diseased and stented arteries to help renal artery implant development. J. Magn. Reson. Imaging 2013;. © 2013 Wiley Periodicals, Inc.

    View details for DOI 10.1002/jmri.24101

    View details for Web of Science ID 000327756800003

    View details for PubMedID 23553967

  • Evaluation of Marfan patients status post valve-sparing aortic root replacement with 4D flow MAGNETIC RESONANCE IMAGING Hope, T. A., Kvitting, J. E., Hope, M. D., Miller, D. C., Markl, M., Herfkens, R. J. 2013; 31 (9): 1479-1484

    Abstract

    BACKGROUND: Over the past two decades elective valve-sparing aortic root replacement (V-SARR) has become more common in the treatment of patients with aortic root and ascending aortic aneurysms. Currently there are little data available to predict complications in the post-operative population. The study goal was to determine if altered flow patterns in the thoracic aorta, as measured by MRI, are associated with complications after V-SARR. METHODS: Time-resolved three-dimensional phase-contrast MRI (4D flow) was used to image 12 patients with Marfan syndrome after V-SARR. The patients were followed up for an average of 5.8years after imaging and 8.2years after surgery. Additionally 5 volunteers were imaged for comparison. Flow profiles were visualized during peak systole using streamlines. Wall shear stress estimates and normalized flow displacement were evaluated at multiple planes in the thoracic aorta. RESULTS: During the follow-up period, a single patient developed a Stanford Type B aortic dissection. At initial imaging, prior to the development of the dissection, the patient had altered flow patterns, wall shear stress estimates, and increased normalized flow displacement in the thoracic aorta in comparison to the remaining V-SARR patients and volunteers. CONCLUSIONS: This is the first follow-up study of patients after 4D flow imaging. An aortic dissection developed in one patient with altered flow patterns and hemodynamic stresses in the thoracic aorta. These results suggest that flow and altered hemodynamics may play a role in the development of post-operative intramural hematomas and dissections.

    View details for DOI 10.1016/j.mri.2013.04.003

    View details for Web of Science ID 000325839700003

    View details for PubMedID 23706513

  • Improvement of gadoxetate arterial phase capture with a high spatio-temporal resolution multiphase three-dimensional SPGR-dixon sequence. Journal of magnetic resonance imaging Hope, T. A., Saranathan, M., Petkovska, I., Hargreaves, B. A., Herfkens, R. J., Vasanawala, S. S. 2013; 38 (4): 938-945

    Abstract

    PURPOSE: To determine whether a multiphase method with high spatiotemporal resolution (STR) by means of a combination of parallel imaging, pseudorandom sampling and temporal view sharing improves the capture and intensity of gadoxetate arterial phase images as well as lesion enhancement. MATERIALS AND METHODS: Thirty-seven patients were imaged with a conventional spoiled gradient echo acquisition and 48 with a high STR multiphase acquisition after the administration of gadoxetate. Arterial phase capture, image quality, and quality of fat suppression were qualitatively graded. Fourteen lesions in the conventional group and 28 in the high STR multiphase group were imaged, including 34 focal nodular hyperplasias. The ratio of lesion to parenchyma enhancement as well as relative hepatic artery enhancement were calculated. Chi-squared, Mann-Whitney U and student t-tests were used to compare differences. RESULTS: The high STR multiphase acquisition included the arterial phase more frequently than conventional acquisitions (P < 0.001), with the arterial phase missed in 17% (95% CI of 4-28%) of patients with conventional acquisition compared with 2% (95% CI of 0-6%) with the high STR multiphase acquisition. There was no loss of image quality or degree of fat saturation. Additionally, there was increased relative intensity of the hepatic arteries (P < 0.001) as well as lesion enhancement (P = 0.01). CONCLUSION: The high STR multiphase acquisition resulted in more reliable gadoxetate arterial phase capture compared with a conventional acquisition while preserving image quality with robust fat saturation J. Magn. Reson. Imaging 2013. © 2013 Wiley Periodicals, Inc.

    View details for DOI 10.1002/jmri.24048

    View details for PubMedID 23371926

  • Respiration-induced Deformations of the Superior Mesenteric and Renal Arteries in Patients with Abdominal Aortic Aneurysms. Journal of vascular and interventional radiology Suh, G., Choi, G., Herfkens, R. J., Dalman, R. L., Cheng, C. P. 2013; 24 (7): 1035-1042

    Abstract

    To quantify respiration-induced deformations of the superior mesenteric artery (SMA), left renal artery (LRA), and right renal artery (RRA) in patients with small abdominal aortic aneurysms (AAAs).Sixteen men with AAAs (age 73 y ± 7) were imaged with contrast-enhanced magnetic resonance angiography during inspiratory and expiratory breath-holds. Centerline paths of the aorta and visceral arteries were acquired by geometric modeling and segmentation techniques. Vessel translations and changes in branching angle and curvature resulting from respiration were computed from centerline paths.With expiration, the SMA, LRA, and RRA bifurcation points translated superiorly by 12.4mm ± 9.5, 14.5mm ± 8.8, and 12.7mm ± 6.4 (P < .001), and posteriorly by 2.2mm ± 2.7, 4.9mm ± 4.2, and 5.6mm ± 3.9 (P < .05), respectively, and the SMA translated rightward by 3.9mm ± 4.9 (P < .01). With expiration, the SMA, LRA, and RRA angled upward by 9.7° ± 6.4, 7.5° ± 7.8, and 4.9° ± 5.3, respectively (P < .005). With expiration, mean curvature increased by 0.02mm(-1) ± 0.01, 0.01mm(-1) ± 0.01, and 0.01mm(-1) ± 0.01 in the SMA, LRA, and RRA, respectively (P < .05). For inspiration and expiration, RRA curvature was greater than in other vessels (P < .025).With expiration, the SMA, LRA, and RRA translated superiorly and posteriorly as a result of diaphragmatic motion, inducing upward angling of vessel branches and increased curvature. In addition, the SMA exhibited rightward translation with expiration. The RRA was significantly more tortuous, but deformed less than the other vessels during respiration.

    View details for DOI 10.1016/j.jvir.2013.04.006

    View details for PubMedID 23796090

  • 2013 ACCF/ACR/ASE/ASNC/SCCT/SCMR Appropriate Utilization of Cardiovascular Imaging in Heart Failure: An Executive Summary A Joint Report of the ACR Appropriateness Criteria (R) Committee and the ACCF Appropriate Use Criteria Task Force JOURNAL OF THE AMERICAN COLLEGE OF RADIOLOGY White, R. D., Patel, M. R., Abbara, S., Bluemke, D. A., Herfkens, R. J., Picard, M., Shaw, L. J., Silver, M., Stillman, A. E., Udelson, J. 2013; 10 (7): 493-500

    Abstract

    The ACR and the American College of Cardiology Foundation (ACCF) developed a joint process for determining the appropriate utilization (AU) of cardiovascular imaging modalities in heart failure (HF). This report represents an executive summary of the AU document which was aimed at critically and systematically creating, reviewing, and categorizing clinical situations where physicians order or use imaging tests for patients with suspected, incompletely characterized, or known HF.

    View details for DOI 10.1016/j.jacr.2013.05.002

    View details for Web of Science ID 000321998200007

    View details for PubMedID 23827001

  • Pilot prospective evaluation of 99mTc-MDP scintigraphy, 18F NaF PET/CT, 18F FDG PET/CT and whole-body MRI for detection of skeletal metastases. Clinical nuclear medicine Iagaru, A., Young, P., Mittra, E., Dick, D. W., Herfkens, R., Gambhir, S. S. 2013; 38 (7): e290-6

    Abstract

    The aim of this study was to compare Tc-MDP bone scanning, F NaF PET/CT, F FDG PET/CT, and whole-body MRI (WBMRI) for detection of known osseous metastases.This prospective pilot trial (September 2007-April 2009) enrolled 10 participants (5 men, 5 women, 47-81 years old) diagnosed with cancer and known osseous metastases. F NaF PET/CT, F FDG PET/CT, and WBMRI were performed within 1 month for each participant.The image quality and evaluation of extent of disease were superior by F NaF PET/CT compared to Tc-MDP scintigraphy in all patients with skeletal lesions and compared to F FDG PET/CT in 3 of the patients with skeletal metastases. F NaF PET/CT showed osseous metastases where F FDG PET/CT was negative in another 3 participants. Extraskeletal metastases were identified by F FDG PET/CT in 6 participants. WBMRI with the combination of iterative decomposition of water and fat with echo asymmetry and least-squares estimation, short tau inversion recovery, and diffusion-weighted imaging pulse sequences showed fewer lesions than F NaF PET/CT in 5 patients, same number of lesions in 2 patients, and more lesions in 1 patient. WBMRI showed fewer lesions than F FDG in 3 patients and same lesions in 6 patients.Our pilot phase prospective trial demonstrated superior image quality and evaluation of skeletal disease extent with F NaF PET/CT compared to Tc-MDP scintigraphy and F FDG PET/CT, as well as the feasibility of multisequence WBMRI. In addition, F FDG PET/CT provided valuable soft-tissue information that can change disease management. Further evaluation of these findings using the recently introduced PET/MRI scanners is warranted.

    View details for DOI 10.1097/RLU.0b013e3182815f64

    View details for PubMedID 23455520

  • 2013 ACCF/ACR/ASE/ASNC/SCCT/SCMR Appropriate Utilization of Cardiovascular Imaging in Heart Failure: A Joint Report of the American College of Radiology Appropriateness Criteria Committee and the American College of Cardiology Foundation Appropriate Use Criteria Task Force. Journal of the American College of Cardiology Patel, M. R., White, R. D., Abbara, S., Bluemke, D. A., Herfkens, R. J., Picard, M., Shaw, L. J., Silver, M., Stillman, A. E., Udelson, J. 2013; 61 (21): 2207-2231

    View details for DOI 10.1016/j.jacc.2013.02.005

    View details for PubMedID 23500216

  • Intravaginal Gel for Staging of Female Pelvic Cancers-Preliminary Report of Safety, Distention, and Gel-Mucosal Contrast During Magnetic Resonance Examination JOURNAL OF COMPUTER ASSISTED TOMOGRAPHY Young, P., Daniel, B., Sommer, G., Kim, B., Herfkens, R. 2012; 36 (2): 253-256

    Abstract

    To more fully outline cervical and vaginal contours and distend the vagina, we have filled the vagina with sterile water-based gel before the magnetic resonance (MR) examination. The technique is similar to that used for defecating MR proctography and other MR examinations, but has not been well described for MR imaging of female pelvic cancer. We present our preliminary clinical experience, including a review of safety imaging characteristics and maintenance of the distention during the examination.

    View details for DOI 10.1097/RCT.0b013e3182483c05

    View details for Web of Science ID 000302141800018

    View details for PubMedID 22446369

  • Rapid Pediatric Cardiac Assessment of Flow and Ventricular Volume With Compressed Sensing Parallel Imaging Volumetric Cine Phase-Contrast MRI AMERICAN JOURNAL OF ROENTGENOLOGY Hsiao, A., Lustig, M., Alley, M. T., Murphy, M., Chan, F. P., Herfkens, R. J., Vasanawala, S. S. 2012; 198 (3): W250-W259

    Abstract

    The quantification of cardiac flow and ventricular volumes is an essential goal of many congenital heart MRI examinations, often requiring acquisition of multiple 2D phase-contrast and bright-blood cine steady-state free precession (SSFP) planes. Scan acquisition, however, is lengthy and highly reliant on an imager who is well-versed in structural heart disease. Although it can also be lengthy, 3D time-resolved (4D) phase-contrast MRI yields global flow patterns and is simpler to perform. We therefore sought to accelerate 4D phase contrast and to determine whether equivalent flow and volume measurements could be extracted.Four-dimensional phase contrast was modified for higher acceleration with compressed sensing. Custom software was developed to process 4D phase-contrast images. We studied 29 patients referred for congenital cardiac MRI who underwent a routine clinical protocol, including cine short-axis stack SSFP and 2D phase contrast, followed by contrast-enhanced 4D phase contrast. To compare quantitative measurements, Bland-Altman analysis, paired Student t tests, and F tests were used.Ventricular end-diastolic, end-systolic, and stroke volumes obtained from 4D phase contrast and SSFP were well correlated (? = 0.91-0.95; r(2) = 0.83-0.90), with no statistically significant difference. Ejection fractions were well correlated in a subpopulation that underwent higher-resolution compressed-sensing 4D phase contrast (? = 0.88; r(2) = 0.77). Four-dimensional phase contrast and 2D phase contrast flow rates were also well correlated (? = 0.90; r(2) = 0.82). Excluding ventricles with valvular insufficiency, cardiac outputs derived from outlet valve flow and stroke volumes were more consistent by 4D phase contrast than by 2D phase contrast and SSFP.Combined parallel imaging and compressed sensing can be applied to 4D phase contrast. With custom software, flow and ventricular volumes may be extracted with comparable accuracy to SSFP and 2D phase contrast. Furthermore, cardiac outputs were more consistent by 4D phase contrast.

    View details for DOI 10.2214/AJR.11.6969

    View details for Web of Science ID 000301069000006

    View details for PubMedID 22358022

  • Cardiac Imaging: Part 2, Normal, Variant, and Anomalous Configurations of the Coronary Vasculature AMERICAN JOURNAL OF ROENTGENOLOGY Young, P. M., Gerber, T. C., Williamson, E. E., Julsrud, P. R., Herfkens, R. J. 2011; 197 (4): 816-826

    Abstract

    Noninvasive imaging of the heart and coronary vasculature using CT and MRI is a new and exciting opportunity for radiologists. The purpose of this pictorial essay is to review normal and variant anatomy of the coronary arteries and of several coronary anomalies that may be clinically significant. The coronary veins and artifacts simulating disease will also be briefly covered. This article will help radiologists learn and review normal coronary anatomy, normal variants, and coronary anomalies and recognize pitfalls, such as coronary veins and artifacts, that may be confusing when first encountered.The coronary arteries generally are predictable in their origin, course, and perfusion territories. Standardized reporting systems exist for describing the location of specific lesions, and radiologists who interpret CT and MR coronary images should be aware of and should attempt to integrate these reporting schemes into clinical practice.

    View details for DOI 10.2214/AJR.10.7249

    View details for Web of Science ID 000295081000051

    View details for PubMedID 21940568

  • Comparison of MR and Contrast Venography of the Cervical Venous System in Multiple Sclerosis AMERICAN JOURNAL OF NEURORADIOLOGY Zaharchuk, G., Fischbein, N. J., Rosenberg, J., Herfkens, R. J., Dake, M. D. 2011; 32 (8): 1482-1489

    Abstract

    MRV has been proposed as a possible screening method to identify chronic cerebrospinal venous insufficiency, which may play a role in MS. We report our initial experience comparing MRV and CV in MS patients to evaluate venous stenosis and collateral venous drainage.Time-of-flight and time-resolved imaging of contrast kinetics MRV and CV were performed in 39 MS patients. The presence and severity of both IJ vein caliber changes and non-IJ collaterals were graded by using a 4-point scale by 2 radiologists in an independent and blinded manner.Both studies frequently showed venous abnormalities, most commonly IJ flattening at the C1 level and in the lower neck. There was moderate-to-good agreement between the modalities (? = 0.55; 95% CI, 0.45%-0.65%). For collaterals, agreement was only fair (? = 0.30; 95% CI, 0.09%-0.50%). The prevalence of IJ segments graded mild or worse on CV was 54%. If CV was considered a standard, the sensitivity and specificity of MRV was 0.79 (0.71-0.86) and 0.76 (0.67-0.83), respectively. Degree of stenosis was related to the severity of collaterals for CV but not for MRV.IJ caliber changes were seen in characteristic locations on both MRV and CV in MS patients. Agreement between modalities was higher for stenosis than for collaterals. If CV is considered a standard, MRV performance is good but may require additional improvement before MRV can be used for screening.

    View details for DOI 10.3174/ajnr.A2549

    View details for Web of Science ID 000295706200021

    View details for PubMedID 21757521

  • Hemodynamic Changes Quantified in Abdominal Aortic Aneurysms with Increasing Exercise Intensity Using MR Exercise Imaging and Image-Based Computational Fluid Dynamics ANNALS OF BIOMEDICAL ENGINEERING Suh, G., Les, A. S., Tenforde, A. S., Shadden, S. C., Spilker, R. L., Yeung, J. J., Cheng, C. P., Herfkens, R. J., Dalman, R. L., Taylor, C. A. 2011; 39 (8): 2186-2202

    Abstract

    Abdominal aortic aneurysm (AAA) is a vascular disease resulting in a permanent, localized enlargement of the abdominal aorta. We previously hypothesized that the progression of AAA may be slowed by altering the hemodynamics in the abdominal aorta through exercise [Dalman, R. L., M. M. Tedesco, J. Myers, and C. A. Taylor. Ann. N.Y. Acad. Sci. 1085:92-109, 2006]. To quantify the effect of exercise intensity on hemodynamic conditions in 10 AAA subjects at rest and during mild and moderate intensities of lower-limb exercise (defined as 33 ± 10% and 63 ± 18% increase above resting heart rate, respectively), we used magnetic resonance imaging and computational fluid dynamics techniques. Subject-specific models were constructed from magnetic resonance angiography data and physiologic boundary conditions were derived from measurements made during dynamic exercise. We measured the abdominal aortic blood flow at rest and during exercise, and quantified mean wall shear stress (MWSS), oscillatory shear index (OSI), and particle residence time (PRT). We observed that an increase in the level of activity correlated with an increase of MWSS and a decrease of OSI at three locations in the abdominal aorta, and these changes were most significant below the renal arteries. As the level of activity increased, PRT in the aneurysm was significantly decreased: 50% of particles were cleared out of AAAs within 1.36 ± 0.43, 0.34 ± 0.10, and 0.22 ± 0.06 s at rest, mild exercise, and moderate exercise levels, respectively. Most of the reduction of PRT occurred from rest to the mild exercise level, suggesting that mild exercise may be sufficient to reduce flow stasis in AAAs.

    View details for DOI 10.1007/s10439-011-0313-6

    View details for Web of Science ID 000292268900008

    View details for PubMedID 21509633

  • Intraprocedure Visualization of the Esophagus Using Interventional C-arm CT as Guidance for Left Atrial Radiofrequency Ablation ACADEMIC RADIOLOGY Tognolini, A., Al-Ahmad, A., Wang, P. J., Hsia, H. H., Herfkens, R. J., Girard, E., Moore, T., Fahrig, R. 2011; 18 (7): 850-857

    Abstract

    During radiofrequency catheter ablation for atrial fibrillation, the esophagus is at risk for thermal injury. In this study, C-arm computed tomography (CT) was compared to clinical CT, without the administration of oral contrast, to visualize the esophagus and its relationship to the left atrium and the ostia of the pulmonary veins (PVs) during the radiofrequency ablation procedure.Sixteen subjects underwent both cardiac clinical CT and C-arm CT. Computed tomographic scans were performed on a multidetector scanner using a standard electrocardiographically gated protocol. C-arm computed tomographic scans were obtained using either a multisweep protocol with retrospective electrocardiographic gating or a non-gated single-sweep protocol. C-arm and clinical computed tomographic scans were analyzed in a random order and then compared for the following criteria: (1) visualization of the esophagus (yes or no), (2) relationship of esophageal position to the four PVs, and (3) direct contact or absence of a fat pad between the esophagus and the PV antrum.The esophagus was identified in all C-arm and clinical computed tomographic scans. In four cases, orthogonal planes were needed on C-arm CT (inferior PV level). In six patients, the esophageal location on C-arm CT was different from that on CT. Direct contact was reported in 19 of 64 of the segments (30%) examined on CT and in 26 of 64 (41%) on C-arm CT. In five of 64 segments (8%), C-arm CT overestimated a direct contact of the esophagus to the left atrium.C-arm computed tomographic image quality without the administration of oral contrast agents was shown to be sufficient for visualization of the esophagus location during a radiofrequency catheter ablation procedure for atrial fibrillation.

    View details for DOI 10.1016/j.acra.2011.01.023

    View details for Web of Science ID 000292066200010

    View details for PubMedID 21440465

  • Improved cardiovascular flow quantification with time-resolved volumetric phase-contrast MRI PEDIATRIC RADIOLOGY Hsiao, A., Alley, M. T., Massaband, P., Herfkens, R. J., Chan, F. P., Vasanawala, S. S. 2011; 41 (6): 711-720

    Abstract

    Cardiovascular flow is commonly assessed with two-dimensional, phase-contrast MRI (2-D PC-MRI). However, scan prescription and acquisition over multiple planes is lengthy, often requires direct physician oversight and has inconsistent results. Time-resolved volumetric PC-MRI (4-D flow) may address these limitations.We assess the degree of agreement and internal consistency between 2-D and 4-D flow quantification in our clinical population.Software enabling flow calculation from 4-D flow was developed in Java. With IRB approval and HIPAA compliance, 18 consecutive patients without shunts were identified who underwent both (1) conventional 2-D PC-MRI of the aorta and main pulmonary artery and (2) 4-D flow imaging. Aortic and pulmonary flow rates were assessed with both techniques.Both methods showed general agreement in flow rates (?: 0.87-0.90). Systemic and pulmonary arterial flow rates were well-correlated (?: 4-D 0.98-0.99, 2-D 0.93), but more closely matched with 4-D (P < 0.05, Brown-Forsythe). Pulmonary flow rates were lower than systemic rates for 2-D (P < 0.05, two-sample t-test). In a sub-analysis of patients without pulmonary or aortic regurgitation, 2-D showed improved correlation of flow rates while 4-D phase-contrast remained tightly correlated (?: 4-D 0.99-1.00, 2-D 0.99).4-D PC-MRI demonstrates greater consistency than conventional 2-D PC-MRI for flow quantification.

    View details for DOI 10.1007/s00247-010-1932-z

    View details for Web of Science ID 000290544500005

    View details for PubMedID 21221566

  • In-vivo Imaging of Femoral Artery Nitinol Stents for Deformation Analysis JOURNAL OF VASCULAR AND INTERVENTIONAL RADIOLOGY Ganguly, A., Simons, J., Schneider, A., Keck, B., Bennett, N. R., Herfkens, R. J., Coogan, S. M., Fahrig, R. 2011; 22 (2): 244-249

    Abstract

    The authors have developed a direct method to study femoral artery stent deformations in vivo. A previously described imaging and analysis approach based on a calibrated phantom was used to examine stents in human volunteers treated for atherosclerotic disease. In this pilot study, forces on stents were evaluated under different in-vivo flexion conditions.The optimized imaging protocol for imaging with a C-arm computed tomography system was first verified in an in-vivo porcine stent model. Human data were obtained by imaging 13 consenting volunteers with stents in femoral vessels. The affected leg was imaged in straight and bent positions to observe stent deformations. Semiautomatic software was used to calculate the changes in bending, extension, and torsion on the stents for the two positions.For the human studies, tension and bending calculation were successful. Bending was found to compress stent lengths by 4% ± 3% (-14.2 to 1.5 mm), increase their average eccentricity by 10% ± 9% (0.12 to -0.16), and change their mean curvature by 27% ± 22% (0 to -0.005 mm(-1)). Stents with the greatest change in eccentricity and curvature were located behind the knee or in the pelvis. Torsion calculations were difficult because the stents were untethered and are symmetric. In addition, multiple locations in each stent underwent torsional deformations.The imaging and analysis approach developed based on calibrated in vitro measurements was extended to in-vivo data. Bending and tension forces were successfully evaluated in this pilot study.

    View details for DOI 10.1016/j.jvir.2010.10.019

    View details for Web of Science ID 000287166600018

    View details for PubMedID 21276917

  • Quantification of Particle Residence Time in Abdominal Aortic Aneurysms Using Magnetic Resonance Imaging and Computational Fluid Dynamics ANNALS OF BIOMEDICAL ENGINEERING Suh, G., Les, A. S., Tenforde, A. S., Shadden, S. C., Spilker, R. L., Yeung, J. J., Cheng, C. P., Herfkens, R. J., Dalman, R. L., Taylor, C. A. 2011; 39 (2): 864-883

    Abstract

    Hemodynamic conditions are hypothesized to affect the initiation, growth, and rupture of abdominal aortic aneurysms (AAAs), a vascular disease characterized by progressive wall degradation and enlargement of the abdominal aorta. This study aims to use magnetic resonance imaging (MRI) and computational fluid dynamics (CFD) to quantify flow stagnation and recirculation in eight AAAs by computing particle residence time (PRT). Specifically, we used gadolinium-enhanced MR angiography to obtain images of the vessel lumens, which were used to generate subject-specific models. We also used phase-contrast MRI to measure blood flow at supraceliac and infrarenal locations to prescribe physiologic boundary conditions. CFD was used to simulate pulsatile flow, and PRT, particle residence index, and particle half-life of PRT in the aneurysms were computed. We observed significant regional differences of PRT in the aneurysms with localized patterns that differed depending on aneurysm geometry and infrarenal flow. A bulbous aneurysm with the lowest mean infrarenal flow demonstrated the slowest particle clearance. In addition, improvements in particle clearance were observed with increase of mean infrarenal flow. We postulate that augmentation of mean infrarenal flow during exercise may reduce chronic flow stasis that may influence mural thrombus burden, degradation of the vessel wall, and aneurysm growth.

    View details for DOI 10.1007/s10439-010-0202-4

    View details for Web of Science ID 000287213300022

    View details for PubMedID 21103933

  • Respiratory Navigated Free Breathing 3D Spoiled Gradient-Recalled Echo Sequence for Contrast-Enhanced Examination of the Liver: Diagnostic Utility and Comparison With Free Breathing and Breath-Hold Conventional Examinations AMERICAN JOURNAL OF ROENTGENOLOGY Young, P. M., Brau, A. C., Iwadate, Y., Vasanawala, S., Daniel, B. L., Tamrazi, A., Herfkens, R. J. 2010; 195 (3): 687-691

    Abstract

    The purpose of our study was to evaluate image quality in a 3D spoiled gradient-recalled echo (SPGR) sequence that was modified to incorporate respiratory navigation to limit the deleterious effects of respiratory motion and to compare it with conventional scanning during breath-holding and free breathing.Respiratory navigation of 3D SPGR sequences is technically feasible, and image quality is modestly improved over free breathing acquisitions using conventional 3D SPGR sequences. This may represent a promising imaging alternative for patients who cannot hold their breath.

    View details for DOI 10.2214/AJR.09.3892

    View details for Web of Science ID 000281180500022

    View details for PubMedID 20729447

  • Quantification of Hemodynamics in Abdominal Aortic Aneurysms During Rest and Exercise Using Magnetic Resonance Imaging and Computational Fluid Dynamics ANNALS OF BIOMEDICAL ENGINEERING Les, A. S., Shadden, S. C., Figueroa, C. A., Park, J. M., Tedesco, M. M., Herfkens, R. J., Dalman, R. L., Taylor, C. A. 2010; 38 (4): 1288-1313

    Abstract

    Abdominal aortic aneurysms (AAAs) affect 5-7% of older Americans. We hypothesize that exercise may slow AAA growth by decreasing inflammatory burden, peripheral resistance, and adverse hemodynamic conditions such as low, oscillatory shear stress. In this study, we use magnetic resonance imaging and computational fluid dynamics to describe hemodynamics in eight AAAs during rest and exercise using patient-specific geometric models, flow waveforms, and pressures as well as appropriately resolved finite-element meshes. We report mean wall shear stress (MWSS) and oscillatory shear index (OSI) at four aortic locations (supraceliac, infrarenal, mid-aneurysm, and suprabifurcation) and turbulent kinetic energy over the entire computational domain on meshes containing more than an order of magnitude more elements than previously reported results (mean: 9.0-million elements; SD: 2.3 M; range: 5.7-12.0 M). MWSS was lowest in the aneurysm during rest 2.5 dyn/cm(2) (SD: 2.1; range: 0.9-6.5), and MWSS increased and OSI decreased at all four locations during exercise. Mild turbulence existed at rest, while moderate aneurysmal turbulence was present during exercise. During both rest and exercise, aortic turbulence was virtually zero superior to the AAA for seven out of eight patients. We postulate that the increased MWSS, decreased OSI, and moderate turbulence present during exercise may attenuate AAA growth.

    View details for DOI 10.1007/s10439-010-9949-x

    View details for Web of Science ID 000276046600003

    View details for PubMedID 20143263

  • Navigated abdominal T1-W MRI permits free-breathing image acquisition with less motion artifact PEDIATRIC RADIOLOGY Vasanawala, S. S., Iwadate, Y., Church, D. G., Herfkens, R. J., Brau, A. C. 2010; 40 (3): 340-344

    Abstract

    T1-W imaging of the pediatric abdomen is often limited by respiratory motion artifacts. Although navigation has been commonly employed for coronary MRA and T2-W imaging, navigation for T1-W imaging is less developed. Thus, we incorporated a navigator pulse into a fat-suppressed T1-W SPGR sequence such that steady-state contrast was not disrupted. Ten children were scanned after gadolinium administration three times in immediate succession: breath-hold with no navigation, free-breathing with navigation, and free-breathing without navigation. Motion artifacts were scored for each sequence by two radiologists,showing fewer motion artifacts with navigation compared to free-breathing and greater motion artifacts than with breath-holding. This work demonstrates the feasibility and potential utility of navigation for pediatric abdominal T1-W imaging.

    View details for DOI 10.1007/s00247-009-1502-4

    View details for Web of Science ID 000274386700008

    View details for PubMedID 20066407

  • Quantifying In Vivo Hemodynamic Response to Exercise in Patients With Intermittent Claudication and Abdominal Aortic Aneurysms Using Cine Phase-Contrast MRI JOURNAL OF MAGNETIC RESONANCE IMAGING Tenforde, A. S., Cheng, C. P., Suh, G., Herfkens, R. J., Dalman, R. L., Taylor, C. A. 2010; 31 (2): 425-429

    Abstract

    To evaluate rest and exercise hemodynamics in patients with abdominal aortic aneurysms (AAA) and peripheral occlusive disease (claudicants) using phase-contrast MRI.Blood velocities were acquired by means of cardiac-gated cine phase-contrast in a 0.5 Tesla (T) open MRI. Volumetric flow was calculated at the supraceliac (SC), infrarenal (IR), and mid-aneurysm (MA) levels during rest and upright cycling exercise using an MR-compatible exercise cycle.Mean blood flow increased during exercise (AAA: 130%, Claudicants: 136% of resting heart rate) at the SC and IR levels for AAA participants (2.6 +/- 0.6 versus 5.8 +/- 1.6 L/min, P < 0.001 and 0.8 +/- 0.4 versus 5.1 +/- 1.7 L/min, P < 0.001) and claudicants (2.3 +/- 0.5 versus 4.5 +/- 0.9 L/min, P < 0.005 and 0.8 +/- 0.2 versus 3.3 +/- 0.9 L/min, P < 0.005). AAA participants had a significant decrease in renal and digestive blood flow from rest to exercise (1.8 +/- 0.7 to 0.7 +/- 0.6 L/min, P < 0.01). The decrease in renal and digestive blood flow during exercise correlated with daily activity level for claudicants (R = 0.81).Abdominal aortic hemodynamic changes due to lower extremity exercise can be quantified in patients with AAA and claudication using PC-MRI. The redistribution of blood flow during exercise was significant and different between the two disease states.

    View details for DOI 10.1002/jmri.22055

    View details for Web of Science ID 000274117200019

    View details for PubMedID 20099356

  • The Effect of Aging on Deformations of the Superficial Femoral Artery Resulting from Hip and Knee Flexion: Potential Clinical Implications JOURNAL OF VASCULAR AND INTERVENTIONAL RADIOLOGY Cheng, C. P., Choi, G., Herfkens, R. J., Taylor, C. A. 2010; 21 (2): 195-202

    Abstract

    Vessel deformations have been implicated in endoluminal device fractures, and therefore better understanding of these deformations could be valuable for device regulation, evaluation, and design. The purpose of this study is to describe geometric changes of the superficial femoral artery (SFA) resulting from hip and knee flexion in older subjects.The SFAs of seven healthy subjects aged 50-70 years were imaged with magnetic resonance angiography with the legs straight and with hip and knee flexion. From geometric models constructed from these images, axial, twisting, and bending deformations were quantified.There was greater shortening in the bottom third of the SFA than in the top two thirds (top, 5.9% +/- 3.0%; middle, 6.7% +/- 2.1%; bottom, 8.1% +/- 2.0% [mean +/- SD]; P < .05), significant twist in all sections (top, 1.3 degrees /cm +/- 0.8; middle, 1.8 degrees /cm +/- 1.1; bottom, 2.1 degrees /cm +/- 1.3), and greater curvature increase in the bottom third than in the top two thirds (top, 0.15 cm(-1) +/- 0.06; middle, 0.09 cm(-1) +/- 0.07; bottom, 0.41 cm(-1) +/- 0.22; P < .001).The SFA tends to deform more in the bottom third than in the other sections, likely because of less musculoskeletal constraint distal to the adductor canal and vicinity of knee flexion. The SFAs of these older subjects curve off axis with normal joint flexion, probably resulting from known loss of arterial elasticity with age. This slackening of the vessel enables a method for noninvasive quantification of in vivo SFA strain, which may be valuable for treatment planning and device design. In addition, the spatially resolved arterial deformations quantified in this study may be useful for commercial and regulatory device evaluation.

    View details for DOI 10.1016/j.jvir.2009.08.027

    View details for Web of Science ID 000277367600005

    View details for PubMedID 20022767

  • Nephrogenic Systemic Fibrosis in Rats Treated with Erythropoietin and Intravenous Iron RADIOLOGY Hope, T. A., High, W. A., LeBoit, P. E., Chaopathomkul, B., Rogut, V. S., Herfkens, R. J., Brasch, R. C. 2009; 253 (2): 390-398

    Abstract

    To use a rat model for nephrogenic systemic fibrosis (NSF) that was administered high-dose gadodiamide to determine whether the co-administration of erythropoietin (Epo) and intravenous iron potentiated development of skin lesions that are thought to be a marker for the development of NSF.The local committee for animal research approved this study. High-dose gadodiamide was administered, 2.5 mmol per kilogram of body weight for 20 days, or 500 times the U.S. Food and Drug Administration-approved dose, to four groups of Hannover-Wistar rats: group A, gadodiamide only; B, gadodiamide and Epo; C, gadodiamide and intravenous iron; and D, gadodiamide, Epo, and intravenous iron. The animals were sacrificed 7 days after final injection, and the authors examined dermal histologic findings from each animal and measured metal deposition by using inductively coupled plasma mass spectrometry. To compare the effect of metal deposition and cellularity, a linear mixed effects model was used to fit the data within PROC MIXED modeled with rat-specific random effects, and subsequently a Dunnett adjustment was performed.Rats treated with gadodiamide and both Epo and intravenous iron (group D) had significantly worse skin lesions at gross and histologic analysis (P = .004) compared with the rate treated with gadodiamide only (group A). Group D also had increased levels of deposited gadolinium as measured by means of mass spectrometry (P = .012).With a rat model similar to those already existing in the literature, skin changes were more marked in animals exposed to gadodiamide, Epo, and intravenous iron, as opposed to those animals exposed to gadodiamide alone; this experiment suggests that great caution may be warranted when prescribing gadolinium-based contrast agents to patients receiving Epo and intravenous iron.

    View details for DOI 10.1148/radiol.2532090580

    View details for Web of Science ID 000271275800014

    View details for PubMedID 19789237

  • Initial experience characterizing a type I endoleak from velocity profiles using time-resolved three-dimensional phase-contrast MRI JOURNAL OF VASCULAR SURGERY Hope, T. A., Zarins, C. K., Herfkens, R. J. 2009; 49 (6): 1580-1584

    Abstract

    We report the first utilization of time-resolved three-dimensional phase contrast magnetic resonance imaging, termed 4D flow, to image a type I endoleak after endovascular aneurysm repair. The combination of 4D flow and a traditional magnetic resonance angiogram can aid in the accurate detection and characterization of endoleaks by combining the three-dimensional resolution of cross-sectional imaging with the temporally resolved velocity data of Doppler ultrasound.

    View details for DOI 10.1016/j.jvs.2009.01.010

    View details for Web of Science ID 000266681000031

    View details for PubMedID 19223146

  • Nephrogenic Systemic Fibrosis in Patients With Chronic Kidney Disease Who Received Gadopentetate Dimeglumine INVESTIGATIVE RADIOLOGY Hope, T. A., Herfkens, R. J., Denianke, K. S., LeBoit, P. E., Hung, Y., Weil, E. 2009; 44 (3): 135-139

    Abstract

    To determine the prevalence of nephrogenic systemic fibrosis (NSF) in patients with chronic kidney disease (CKD) who have received gadopentetate dimeglumine.We retrospectively studied all patients who underwent contrast-enhanced magnetic resonance imagings (CE-MRIs) between January 1, 2004 and May 31, 2007, in the Kaiser Permanente Medical Care Program, a managed care organization providing care for more than 3.3 million residents in Northern California. All patients received gadopentetate dimeglumine. We used 4 methods to discover cases of NSF: review of pathology slides, review of coded diagnosis, review of visits to dermatologists and rheumatologists, and surveys of physicians.During the study period 115,252 CE-MRIs were performed, including 676 in 530 patients receiving dialysis (92% on chronic dialysis and 8% on acute dialysis) and 3,423 in 2,862 patients with elevated serum creatinine levels at the time of gadolinium chelate administration. One dialysis patient had a definite diagnosis of NSF. In 3 additional patients, 1 on chronic dialysis and 2 with CKD, NSF could not be ruled out.The prevalence of NSF in patients with CKD who received gadopentetate dimeglumine is lower than previously reported in patients who have received less stable formulations of gadolinium chelates.The prevalence of NSF in our patient population is likely underreported as all patients were not individually examined and histology was not available in the majority of patients. Furthermore, the prevalence is likely effected by the lower average dose and frequency of gadolinium chelate administration in this study compared with previous reports in the literature.

    View details for Web of Science ID 000263576800002

    View details for PubMedID 19151610

  • MRI and H-1 MRS of The Breast: Presence of a Choline Peak as Malignancy Marker is Related to k21 Value of the Tumor in Patients with Invasive Ductal Carcinoma BREAST JOURNAL Geraghty, P. R., van den Bosch, M. A., Spielman, D. M., Hunjan, S., Birdwell, R. L., Fong, K. J., Stables, L. A., Zakhour, M., Herfkens, R. J., Ikeda, D. M. 2008; 14 (6): 574-580

    Abstract

    To assess which specific morphologic features, enhancement patterns, or pharmacokinetic parameters on breast Magnetic Resonance Imaging (MRI) could predict a false-negative outcome of Proton MR Spectroscopy ((1)H MRS) exam in patients with invasive breast cancer. Sixteen patients with invasive ductal carcinoma of the breast were prospectively included and underwent both, contrast-enhanced breast MRI and (1)H MRS examination of the breast. The MR images were reviewed and the lesions morphologic features, enhancement patterns and pharmacokinetic parameters (k21-value) were scored according to the ACR BI-RADS-MRI lexicon criteria. For the in vivo MRS studies, each spectrum was evaluated for the presence of choline based on consensus reading. Breast MRI and (1)H MRS data were compared to histopathologic findings. In vivo (1)H MRS detected a choline peak in 14/16 (88%) cancers. A false-negative (1)H MRS study occurred in 2/16 (14%) cancer patients. K21 values differed between both groups: the 14 choline positive cancers had k21 values ranging from 0.01 to 0.20/second (mean 0.083/second), whereas the two choline-negative cancers showed k21 values of 0.03 and 0.05/second, respectively (mean 0.040/second). Also enhancement kinetics did differ between both groups; typically both cancers that were choline-negative showed a late phase plateau (100%), whereas this was only shown in 5/14 (36%) of the choline positive cases. There was no difference between both groups with regard to morphologic features on MRI. This study showed that false-negative (1)H MRS examinations do occur in breast cancer patients, and that the presence of a choline peak on (1)H MRS as malignancy marker is related to the k21 value of the invasive tumor being imaged.

    View details for DOI 10.1111/j.1524-4741.2008.00650.x

    View details for Web of Science ID 000261085300011

    View details for PubMedID 19000051

  • The aortopathy of bicuspid aortic valve disease has distinctive patterns and usually involves the transverse aortic arch JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY Fazel, S. S., Mallidi, H. R., Lee, R. S., Sheehan, M. P., Liang, D., Fleischman, D., Herfkens, R., Mitchell, S., Miller, D. C. 2008; 135 (4): 901-U54

    Abstract

    Bicuspid aortic valves are associated with a poorly characterized connective tissue disorder that predisposes to aortic catastrophes. Because no criterion exists dictating the appropriate extent of aortic resection in aneurysmal disease of the bicuspid aortic valve, we studied the patterns of aortic dilation in this population.Sixty-four patients with bicuspid aortic valves who underwent computed tomographic or magnetic resonance angiography and echocardiography were retrospectively identified between January 2002 and March 2006. Orthonormal 2-dimensional or 3-dimensional aortic diameters were measured at 10 levels. Agglomerative hierarchic clustering with centered correlation distance measurements and complete linkage analysis was used to detect distinct patterns of aortic dilatation.Mean aortic diameter was 28.1 +/- 0.7 mm at the annulus and 21.7 +/- 0.4 mm at the diaphragmatic hiatus. The aorta was largest in the tubular ascending aorta (45.9 +/- 1.0 mm). Compared with the descending aorta, the transverse aortic arch was also dilated (P < .01). Cluster analysis showed 4 patterns of aortic dilatation: cluster I, aortic root alone (n = 8, 13%); cluster II, tubular ascending aorta alone (n = 9, 14%); cluster III, tubular portion and transverse arch (n = 18, 28%); and, cluster IV, aortic root and tubular portion with tapering across the transverse arch (n = 29, 45%).Distinct patterns of aortic dilatation in patients with bicuspid aortic valves call for an individualized degree of aortic replacement to minimize late aortic complications and reoperation. Patients in clusters III and IV should have transverse arch replacement (plus concomitant root replacement in cluster IV). Patients in cluster I should undergo complete aortic root replacement, whereas in patients in cluster II supracommissural ascending aortic grafting is adequate.

    View details for DOI 10.1016/j.jtcvs.2008.01.022

    View details for Web of Science ID 000254423600028

    View details for PubMedID 18374778

  • Technical advances in cardiovascular imaging. Seminars in thoracic and cardiovascular surgery Fleischmann, D., Liang, D. H., Herfkens, R. J. 2008; 20 (4): 333-339

    Abstract

    Cardiovascular imaging technology is continuously evolving and provides an increasing array of tests to evaluate cardiovascular morphology and function. A basic understanding of imaging technology is helpful to select the best modality to answer a specific clinical question. This article provides a brief overview of recent technical developments in computed tomography (CT), magnetic resonance (MR), and echocardiography, which have increased our diagnostic understanding and may modulate treatment planning of patients with cardiovascular diseases: electrocardiographically (ECG)-gated CT, 4D-flow magnetic resonance imaging (MRI), and three-dimensional (3D) echocardiography.

    View details for DOI 10.1053/j.semtcvs.2008.11.015

    View details for PubMedID 19251174

  • Imaging of the thoracic aorta with time-resolved three-dimensional phase-contrast MRI: a review. Seminars in thoracic and cardiovascular surgery Hope, T. A., Herfkens, R. J. 2008; 20 (4): 358-364

    Abstract

    Time-resolved three-dimensional (3D) phase-contrast (PC) magnetic resonance imaging (MRI), or four-dimensional (4D) flow, is able to provide robust 3D images with three-directional velocities. This review discusses the technique and application of 4D flow in the imaging of thoracic aortic pathologies. It has been instrumental in describing normal flow patterns throughout the cardiac cycle in the ascending and descending aorta and has shown the variety of flow patterns that exist in ascending aortic aneurysms.

    View details for DOI 10.1053/j.semtcvs.2008.11.013

    View details for PubMedID 19251177

  • Comparison of flow patterns in ascending aortic aneurysms and volunteers using four-dimensional magnetic resonance velocity mapping JOURNAL OF MAGNETIC RESONANCE IMAGING Hope, T. A., Markl, M., Wigstrom, L., Alley, M. T., Miller, D. C., Herfkens, R. J. 2007; 26 (6): 1471-1479

    Abstract

    To determine the difference in flow patterns between healthy volunteers and ascending aortic aneurysm patients using time-resolved three-dimensional (3D) phase contrast magnetic resonance velocity (4D-flow) profiling.4D-flow was performed on 19 healthy volunteers and 13 patients with ascending aortic aneurysms. Vector fields placed on 2D planes were visually graded to analyze helical and retrograde flow patterns along the aortic arch. Quantitative analysis of the pulsatile flow was carried out on manually segmented planes.In volunteers, flow progressed as follows: an initial jet of blood skewed toward the anterior right wall of the ascending aorta is reflected posterolaterally toward the inner curvature creating opposing helices, a right-handed helix along the left wall and a left-handed helix along the right wall; retrograde flow occurred in all volunteers along the inner curvature between the location of the two helices. In the aneurysm patients, the helices were larger; retrograde flow occurred earlier and lasted longer. The average velocity decreased between the ascending aorta and the transverse aorta in volunteers (47.9 mm/second decrease, P = 0.023), while in aneurysm patients the velocity increased (145 mm/second increase, P < 0.001).Dilation of the ascending aorta skews normal flow in the ascending aorta, changing retrograde and helical flow patterns.

    View details for DOI 10.1002/jmri.21082

    View details for Web of Science ID 000252012100013

    View details for PubMedID 17968892

  • Molecular imaging techniques in body imaging RADIOLOGY Margolis, D. J., Hoffman, J. M., Herfkens, R. J., Jeffrey, R. B., Quon, A., Gambhir, S. S. 2007; 245 (2): 333-356

    Abstract

    Molecular imaging of the body involves new techniques to image cellular biochemical processes, which results in studies with high sensitivity, specificity, and signal-to-background. The most prevalently used molecular imaging technique in body imaging is currently fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET). FDG PET has become the method of choice for the staging and restaging of many of the most common cancers, including lymphoma, lung cancer, breast cancer, and colorectal cancer. FDG PET has also become extremely valuable in monitoring the response to therapeutic drugs in many cancers. New PET agents, such as fluorothymidine and acetate, have also shown promise in the evaluation of response to therapy and in the staging of prostate cancer. Magnetic resonance (MR) spectroscopy has shown promise in the evaluation of prostate cancer. Breast cancer evaluation benefits from advances in spectroscopic imaging and contrast-enhanced kinetic evaluation of vascular permeability, which is altered in neoplastic processes because of release of angiogenic factors. Superparamagnetic iron oxide (SPIO) particles represent the first of an expanding line of MR contrast agents that target specific cellular processes. SPIO particles have also been used in the evaluation of the cirrhotic liver and at MR lymphangiography.

    View details for DOI 10.1148/radiol.2452061117

    View details for Web of Science ID 000250343800007

    View details for PubMedID 17940297

  • Detection of bone metastases: Assessment of integrated FDG PET/CT imaging RADIOLOGY Taira, A. V., Herfkens, R. J., Gambhir, S. S., Quon, A. 2007; 243 (1): 204-211

    Abstract

    To retrospectively evaluate the positive predictive value (PPV) of fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) in the identification of malignant bone lesions when the PET and CT findings are discordant and concordant.The study conformed to HIPAA standards, and the need for informed consent was waived by the institutional review board that approved the study. FDG PET/CT reports of 712 patients were reviewed to identify patients with malignant bone lesions. Fifty-nine patients (30 female and 29 male patients; age range, 10-82 years) with 113 lesions were analyzed. With use of confirmation from histopathologic examination or clinical follow-up, the PPVs of the integrated examination and of the stand-alone CT and PET components of the examination were calculated. The results were stratified according to cancer type, chemotherapy status, and number of bone lesions and were compared by using Fisher exact tests.Of 47 lesions with positive findings at both PET and CT, 46 were malignant and one was benign, for a PPV of 98%. Of 31 lesions with positive findings at PET and negative findings at CT, 19 were malignant and 12 were benign, for a PPV of 61%. Of 35 lesions with negative findings at PET and positive findings at CT, six were malignant and 29 were benign, for a PPV of 17%. Independently, the PPV of all lesions with positive findings at PET was significantly higher than that of all lesions with positive findings at CT. Chemotherapy status for lesions with positive findings at CT and the number of lesions per patient had a statistically significant effect on the PPV of examinations (P = .02 and P < .001, respectively).PET/CT has a very high PPV for bone metastases (98%) when the findings at PET and CT are concordant; however, in lesions with discordant PET and CT findings at the integrated examination, PPV is markedly diminished.

    View details for DOI 10.1148/radiol.2431052104

    View details for Web of Science ID 000245312500025

    View details for PubMedID 17392254

  • Water-selective spectral-spatial contrast-enhanced breast MRI for cancer detection in patients with extracapsular and injected free silicone MAGNETIC RESONANCE IMAGING Po, J., Margolis, D. J., Cunningham, C. H., Herfkens, R. J., Ikeda, D. M., Daniel, B. L. 2006; 24 (10): 1363-1367

    Abstract

    This study investigates the use of contrast-enhanced, T1-weighted, water-selective spectral-spatial 3D gradient echo magnetic resonance imaging (MRI) with magnetization transfer (3DSSMT) for detecting breast cancer in patients with intraparenchymal silicone.Water-selective 3DSSMT provides superior fat and silicone suppression in patients with free silicone as compared with conventional fat saturation. It enables direct, high-quality, high-spatial-resolution, T1-weighted breast MRI of contrast enhancement without the need for subtraction processing and aids diagnosis of cancer in the breast with free silicone.

    View details for DOI 10.1016/j.mri.2006.08.003

    View details for Web of Science ID 000242946800011

    View details for PubMedID 17145408

  • Aortoiliac hemodynamic and morphologic adaptation to chronic spinal cord injury JOURNAL OF VASCULAR SURGERY Yeung, J. J., Kim, H. J., Abbruzzese, T. A., Vignon-Clementel, I. E., Draney-Blomme, M. T., Yeung, K. K., Perkash, I., Herfkens, R. J., Taylor, C. A., Dalman, R. L. 2006; 44 (6): 1254-1265

    Abstract

    Reduced lower limb blood flow and resistive hemodynamic conditions potentially promote aortic inflammation and aneurysmal degeneration. We used abdominal ultrasonography, magnetic resonance imaging, and computational flow modeling to determine the relationship between reduced infrarenal aortic blood flow in chronic spinal cord injury (SCI) subjects and risk for abdominal aortic aneurysm (AAA) disease.Aortic diameter in consecutive SCI subjects (n = 123) was determined via transabdominal ultrasonography. Aortic anatomic and physiologic data were acquired via magnetic resonance angiography (MRA; n = 5) and cine phase-contrast magnetic resonance flow imaging (n = 4) from SCI subjects whose aortic diameter was less than 3.0 cm by ultrasonography. Computational flow models were constructed from magnetic resonance data sets. Results were compared with those obtained from ambulatory control subjects (ultrasonography, n = 129; MRA/phase-contrast magnetic resonance flow imaging, n = 6) who were recruited at random from a larger pool of risk factor-matched individuals without known AAA disease.Age, sex distribution, and smoking histories were comparable between the SCI and control groups. In the SCI group, time since injury averaged 26 +/- 13 years (mean +/- SD). Aortic diameter was larger (P < .01), and the prevalence of large (> or = 2.5 cm; P < .01) or aneurysmal (> or = 3.0 cm; P < .05) aortas was greater in SCI subjects. Paradoxically, common iliac artery diameters were reduced in SCI subjects (< 1.0 cm; 48% SCI vs 26% control; P < .0001). Focal preaneurysmal enlargement was noted in four of five SCI subjects by MRA. Flow modeling revealed normal flow volume, biphasic and reduced oscillatory flow, slower pressure decay, and reduced wall shear stress in the SCI infrarenal aorta.Characteristic aortoiliac hemodynamic and morphologic adaptations occur in response to chronic SCI. Slower aortic pressure decay and reduced wall shear stress after SCI may contribute to mural degeneration, enlargement, and an increased prevalence of AAA disease.

    View details for DOI 10.1016/j.jvs.2006.08.026

    View details for Web of Science ID 000242564400022

    View details for PubMedID 17145427

  • Indirect MR lymphangiography of the head and neck using conventional gadolinium contrast: A pilot study in humans INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS Loo, B. W., Draney, M. T., Sivanandan, R., Ruehm, S. G., Pawlicki, T., Xing, L., Herfkens, R. J., Le, Q. 2006; 66 (2): 462-468

    Abstract

    To evaluate indirect magnetic resonance lymphangiography (MR-LAG) using interstitial injection of conventional gadolinium contrast (gadoteridol and gadopentetate dimeglumine) for delineating the primary lymphatic drainage of head-and-neck sites.We performed head-and-neck MR-LAG in 5 healthy volunteers, with injection of dermal and mucosal sites. We evaluated the safety of the procedure, the patterns of enhancement categorized by injection site and nodal level, the time course of enhancement, the optimal concentration and volume of contrast, and the optimal imaging sequence.The worst side effects of interstitial contrast injection were brief, mild pain and swelling at the injected sites that were self-limited. MR-LAG resulted in consistent visualization of the primary lymphatic drainage pattern specific to each injected site, which was reproducible on repeated examinations. The best enhancement was obtained with injection of small volumes (0.3-0.5 mL) of either agent diluted, imaging within 5-15 min of injection, and a three-dimensional fast spoiled gradient echo sequence with magnetization transfer.We found head-and-neck MR-LAG to be a safe, convenient imaging method that provides functional information about the lymphatic drainage of injected sites. Applied to head-and-neck cancer, it has the potential to identify sites at highest risk of occult metastatic spread for radiotherapy or surgical planning, and possibly to visualize micrometastases.

    View details for DOI 10.1016/j.ijrobp.2006.05.045

    View details for Web of Science ID 000240699500024

    View details for PubMedID 16965993

  • Abdominal aortic hemodynamics in young healthy adults at rest and during lower limb exercise: quantification using image-based computer modeling AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY Tang, B. T., Cheng, C. P., Draney, M. T., Wilson, N. M., Tsao, P. S., Herfkens, R. J., Taylor, C. A. 2006; 291 (2): H668-H676

    Abstract

    Localization of atherosclerotic lesions in the abdominal aorta has been previously correlated to areas of adverse hemodynamic conditions, such as flow recirculation, low mean wall shear stress, and high temporal oscillations in shear. Along with its many systemic benefits, exercise is also proposed to have local benefits in the vasculature via the alteration of these regional flow patterns. In this work, subject-specific models of the human abdominal aorta were constructed from magnetic resonance angiograms of five young, healthy subjects, and computer simulations were performed under resting and exercise (50% increase in resting heart rate) pulsatile flow conditions. Velocity fields and spatial variations in mean wall shear stress (WSS) and oscillatory shear index (OSI) are presented. When averaged over all subjects, WSS increased from 4.8 +/- 0.6 to 31.6 +/- 5.7 dyn/cm2 and OSI decreased from 0.22 +/- 0.03 to 0.03 +/- 0.02 in the infrarenal aorta between rest and exercise. WSS significantly increased, whereas OSI decreased between rest and exercise at the supraceliac, infrarenal, and suprabifurcation levels, and significant differences in WSS were found between anterior and posterior sections. These results support the hypothesis that exercise provides localized benefits to the cardiovascular system through acute mechanical stimuli that trigger longer-term biological processes leading to protection against the development or progression of atherosclerosis.

    View details for DOI 10.1152/ajpheart.01301.2005

    View details for Web of Science ID 000239020300021

    View details for PubMedID 16603687

  • In vivo MR angiographic quantification of axial and twisting deformations of the superficial femoral artery resulting from maximum hip and knee flexion JOURNAL OF VASCULAR AND INTERVENTIONAL RADIOLOGY Cheng, C. P., Wilson, N. M., Hallett, R. L., Herfkens, R. J., Taylor, C. A. 2006; 17 (6): 979-987

    Abstract

    The goal of this study was to quantify in vivo deformations of the superficial femoral artery (SFA) during maximum knee and hip flexion with use of magnetic resonance (MR) angiography to improve description of the complex, dynamic SFA environment.Contrast medium-enhanced MR angiography was performed on the leg vasculature of eight healthy adults in the supine and fetal positions. The SFA was defined as the centerline path of the iliofemoral segment from the profunda femoris to the descending genicular artery. Deformations that resulted from flexion from the supine position to the fetal position were quantified with the SFA path and its branches.Fourteen SFAs shortened from the supine position to fetal position, whereas two lengthened. Six of eight left SFAs twisted counterclockwise, and seven of eight right SFAs twisted clockwise. Straightness percentages for supine and fetal SFAs were 99.1%+/-0.4% and 98.7%+/-0.6%, respectively. From the supine position to the fetal position, the SFA shortened 13%+/-11% (P<.001) and twisted 60 degrees+/-34 degrees (P<.001). SFA arc length and percent shortening were strongly correlated (r>.8) between left and right limbs; however, no significant correlation existed for SFA twist angle.Complex and varying vascular and muscular anatomy among study participants made SFA lengths and deformations from the supine position to the fetal position unpredictable a priori; however, there were strong symmetries between left and right SFAs in terms of arc length, length change, and direction of twist. The data show that, from the supine position to the fetal position, the SFA tended to shorten and twist substantially, suggesting these as possible fracture mechanisms and also providing important parameters for stent design.

    View details for DOI 10.1097/01.RVI.0000220367.62137.E8

    View details for Web of Science ID 000238334500006

    View details for PubMedID 16778231

  • Peri-infarct ischemia determined by cardiovascular magnetic resonance evaluation of myocardial viability and stress perfusion predicts future cardiovascular events in patients with severe ischemic cardiomyopathy JOURNAL OF CARDIOVASCULAR MAGNETIC RESONANCE Tsukiji, M., Nguyen, P., Narayan, G., Hellinger, J., Chan, F., Herfkens, R., Pauly, J. M., McConnell, M. V., Yang, P. C. 2006; 8 (6): 773-779

    Abstract

    We assessed whether cardiovascular magnetic resonance imaging (CMR) of peri-infarct ischemia provides prognostic information in severe ischemic cardiomyopathy (ICM) patients referred for revascularization.Twenty-one patients with severe ICM were recruited prospectively for combined stress adenosine perfusion, late gadolinium enhancement, and rest perfusion studies. The patients were followed for in-hospital and post-discharge cardiovascular events.During 12+/- 9.8 months follow-up, 67% of the patients with peri-infarct ischemia and 13% of the patients without peri-infarct ischemia had cardiovascular events (p = 0.03). CONCLUSION. In severe ICM patients, the presence of peri-infarct ischemia was associated with a higher incidence of cardiovascular events.

    View details for DOI 10.1080/10976640600737615

    View details for Web of Science ID 000241485600002

    View details for PubMedID 17060098

  • The lactating breast: Contrast-enhanced MR Imaging of normal tissue and cancer RADIOLOGY Espinosa, L. A., Daniel, B. L., Vidarsson, L., Zakhour, M., Ikeda, D. M., Herfkens, R. J. 2005; 237 (2): 429-436

    Abstract

    To retrospectively describe the magnetic resonance (MR) imaging characteristics of normal breast tissue and breast cancer in the setting of lactation.The HIPAA-compliant study was exempt from institutional approval, and informed consent was not required. Unilateral MR imaging of 10 breasts was performed in seven lactating patients aged 27-42 years. For the three patients in whom both breasts were imaged, each breast was imaged on a separate day. Nonenhanced T1-weighted and fat-saturated T2-weighted images and contrast material-enhanced dynamic three-dimensional (3D) T1-weighted spiral gradient-echo images interleaved with T1-weighted high-spatial-resolution 3D gradient-echo images (2.0 x 1.0 x 0.4-mm voxels) were obtained. Three readers in consensus assessed the glandular density, T2-weighted signal intensity, milk duct appearance, and contrast enhancement in normal and tumor-containing breast regions. The pharmacokinetic contrast enhancement parameters of tumors were compared with those of normal tissue by using Student t and Mann-Whitney tests.MR findings of normal breast tissue in the seven women included increased glandular density in six women, high T2-weighted signal intensity in six, dilated central ducts in seven, and rapid initial glandular contrast enhancement in seven. MR findings of invasive ductal carcinoma in five women, compared with findings of the normal glandular tissue, included lower T2-weighted signal intensity in five women, more avid and rapid contrast enhancement in five, and early contrast enhancement washout in four. One minute after contrast agent injection, tumor signal intensity increased significantly more than normal lactating tissue signal intensity (153% vs 60% from baseline, P = .016). The median two-compartment model K(21) exchange rate in the tumors, 0.078 sec(-1), was significantly faster than the K(21) exchange rate in normal tissue, 0.011 sec(-1) (P = .03).Normal lactating glands have increased density, high T2-weighted signal intensity, and rapid moderate contrast enhancement. Breast cancers are visible during lactation owing to their lower signal intensity and more intense initial contrast enhancement with early washout compared with normal breast tissue.

    View details for DOI 10.1148/radiol.2372040837

    View details for Web of Science ID 000232743300008

    View details for PubMedID 16244250

  • Contrast-enhanced MRI of ductal carcinoma in situ: Characteristics of a new intensity-modulated parametric mapping technique correlated with histopathologic findings JOURNAL OF MAGNETIC RESONANCE IMAGING Mariano, M. N., van den Bosch, M. A., Daniel, B. L., Nowels, K. W., Birdwell, R. L., Fong, K. J., Desmond, P. S., Plevritis, S., Stables, L. A., Zakhour, M., Herfkens, R. J., Ikeda, D. M. 2005; 22 (4): 520-526

    Abstract

    To identify morphologic and dynamic enhancement magnetic resonance imaging (MRI) features of pure ductal carcinoma in situ (DCIS) by using a new intensity-modulated parametric mapping technique, and to correlate the MRI features with histopathologic findings.Fourteen patients with pure DCIS on pathology underwent conventional mammography and contrast-enhanced (CE) MRI using the intensity-modulated parametric mapping technique. The MR images were reviewed and the lesions were categorized according to morphologic and kinetic criteria from the ACR BI-RADS-MRI Lexicon, with BI-RADS 4 and 5 lesions classified as suspicious.With the use of a kinetic curve shape analysis, MRI classified seven of 14 lesions (50%) as suspicious, including four with initial-rapid/late-washout and three with initial-rapid/late-plateau. Using morphologic criteria, MRI classified 10/14 (71%) as suspicious, with the most prominent morphologic feature being a regional enhancement pattern. Using the intensity modulated parametric mapping technique, MRI classified 12/14 cases (86%) as suspicious. Parametric mapping identified all intermediate- and high-grade DCIS lesions.The intensity-modulated parametric mapping technique for breast MRI resulted in the highest detection rate for the DCIS cases. Furthermore, the parametric mapping technique identified all intermediate- and high-grade DCIS lesions, suggesting that a negative MRI using the parametric mapping technique may exclude intermediate- and high-grade DCIS. This finding has potential clinical implications.

    View details for DOI 10.1002/jmri.20405

    View details for Web of Science ID 000232317700010

    View details for PubMedID 16142701

  • Time-resolved three-dimensional magnetic resonance velocity mapping of aortic flow in healthy volunteers and patients after valve-sparing aortic root replacement JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY Markl, M., Draney, M. T., Miller, D. C., Levin, J. M., Williamson, E. E., Pelc, N. J., Liang, D. H., Herfkens, R. J. 2005; 130 (2): 456-463

    Abstract

    To provide more complete characterization of ascending aortic blood flow, including vortex formation behind the valve cusps, in healthy subjects and patients after valve-sparing aortic root replacement (David reimplantation).Time-resolved 3-dimensional magnetic resonance imaging velocity mapping was performed to analyze pulsatile blood flow by using encoded 3-directional vector fields in the thoracic aortas of 10 volunteers and 12 patients after David reimplantation using a cylindrical tube graft (T. David I) and two versions of neosinus recreation (T. David-V and T. David-V-S mod ). Aortic flow was evaluated by using 3-dimensional time-resolved particle traces and velocity vector fields reformatted onto 2-dimensional planes. Semiquantitative data were derived by using a blinded grading system (0-3: 0, none; 1, minimal; 2, medium; 3, prominent) to analyze the systolic vortex formation behind the cusps, as well as retrograde and helical flow in the ascending aorta.Systolic vortices were seen in both coronary sinuses of all volunteers (greater in the left sinus [2.5 +/- 0.5] than the right [1.8 +/- 0.8]) but in only 4 of 10 noncoronary sinuses (0.7 +/- 0.9). Comparable coronary vortices were detected in all operated patients. Vorticity was minimal in the noncoronary cusp in T. David-I repairs (0.7 +/- 0.7) but was prominent in T. David-V noncoronary graft pseudosinuses (1.5 +/- 0.6; P = .035). Retrograde flow (P = .001) and helicity (P = .028) were found in all patients but were not distinguishable from normal values in the T. David-V-S mod patients.Coronary cusp vorticity was preserved after David reimplantation, regardless of neosinus creation. Increased retrograde flow and helicity were more prominent in T. David-V patients. These novel magnetic resonance imaging methods can assess the clinical implications of altered aortic flow dynamics in patients undergoing various types of valve-sparing aortic root replacement.

    View details for DOI 10.1016/j.jtcvs.2004.08.056

    View details for Web of Science ID 000231069700034

    View details for PubMedID 16077413

  • Magnetic resonance imaging characteristics of fibrocystic change of the breast INVESTIGATIVE RADIOLOGY van den Bosch, M. A., Daniel, B. L., Mariano, M. N., Nowels, K. N., Birdwell, R. L., Fong, K. J., Desmond, P. S., Plevritis, S., Stables, L. A., Zakhour, M., Herfkens, R. J., Ikeda, D. M. 2005; 40 (7): 436-441

    Abstract

    The objective of this study was to identify magnetic resonance imaging (MRI) characteristics of fibrocystic change (FCC) of the breast.Fourteen patients with a histopathologic diagnosis of solitary FCC of the breast underwent x-ray mammography and MRI of the breast. Three experienced breast imaging radiologists retrospectively reviewed the MRI findings and categorized the lesions on morphologic and kinetic criteria according to the ACR BI-RADS-MRI Lexicon.The most striking morphologic feature of fibrocystic change was nonmass-like regional enhancement found in 6 of 14 (43%) FCC lesions. Based on morphologic criteria alone, 12 of 14 (86%) lesions were correctly classified as benign. According to analysis of the time-intensity curves, 10 of 14 (71%) FCC lesions were correctly classified as benign.Although FCC has a wide spectrum of morphologic and kinetic features on MRI, it most often presents as a mass or a nonmass-like regional enhancing lesion with benign enhancement kinetics.

    View details for Web of Science ID 000230018100007

    View details for PubMedID 15973135

  • Cardiac CINE imaging with IDEAL water-fat separation and steady-state free precession JOURNAL OF MAGNETIC RESONANCE IMAGING Reeder, S. B., Markl, M., Yu, H. Z., Hellinger, J. C., Herfkens, R. J., Pelc, N. J. 2005; 22 (1): 44-52

    Abstract

    To decompose multicoil CINE steady-state free precession (SSFP) cardiac images acquired at short echo time (TE) increments into separate water and fat images, using an iterative least-squares "Dixon" (IDEAL) method.Multicoil CINE IDEAL-SSFP cardiac imaging was performed in three volunteers and 15 patients at 1.5 T.Measurements of signal-to-noise ratio (SNR) matched theoretical expectations and were used to optimize acquisition parameters. TE increments of 0.9-1.0 msec permitted the use of repetition times (TRs) of 5 msec or less, and provided good SNR performance of the water-fat decomposition, while maintaining good image quality with a minimum of banding artifacts. Images from all studies were evaluated for fat separation and image quality by two experienced radiologists. Uniform fat separation and diagnostic image quality was achieved in all images from all studies. Examples from volunteers and patients are shown.Multicoil IDEAL-SSFP imaging can produce high quality CINE cardiac images with uniform water-fat separation, insensitive to Bo inhomogeneities. This approach provides a new method for reliable fat-suppression in cardiac imaging.

    View details for DOI 10.1002/jmri.20327

    View details for Web of Science ID 000230128900006

    View details for PubMedID 15971192

  • Proximal pulmonary artery blood flow characteristics in healthy subjects measured in an upright posture using MRI: The effects of exercise and age JOURNAL OF MAGNETIC RESONANCE IMAGING Cheng, C. P., Herfkens, R. J., Taylor, C. A., Feinstein, J. A. 2005; 21 (6): 752-758

    Abstract

    To use MRI to quantify blood flow conditions in the proximal pulmonary arteries of healthy children and adults at rest and during exercise in an upright posture.Cine phase-contrast MRI was used to calculate mean flow and reverse flow index (RFI) in the main (MPA), right (RPA), and left (LPA) pulmonary arteries in healthy children and adults in an open-MRI magnet equipped with an upright MRI-compatible ergometer.From rest to exercise (150% resting heart rate), blood flow (liters/minute/m2) increased in the RPA (1.4+/-0.3 vs. 2.5+/-0.4; P<0.001), LPA (1.1+/-0.3 vs. 2.2+/-0.6; P<0.001), and MPA (2.7+/-0.5 vs. 4.9+/-0.5; P<0.001). RFI decreased in the LPA (0.040+/-0.030 vs. 0.017+/-0.018; P<0.02) and MPA (0.025+/-0.024 vs. 0.008+/-0.007; P<0.03). Adults experienced greater retrograde flow in the MPA than the children (0.042+/-0.029 vs. 0.014+/-0.012; P<0.02).It appears that at both rest and during exercise, in children and adults alike, RPA/LPA mean blood flow distribution is predominantly determined by distal vascular resistance, while retrograde flow is affected by proximal pulmonary bifurcation geometry.

    View details for DOI 10.1002/jmri.20333

    View details for Web of Science ID 000229453900012

    View details for PubMedID 15906332

  • Pericardial lymph node involvement in lymphoma as identified on PET CLINICAL NUCLEAR MEDICINE Franc, B., Yoshida, E., Herfkens, R., Goris, M. 2004; 29 (11): 741-742

    View details for Web of Science ID 000224716000021

    View details for PubMedID 15483497

  • Quantification of vessel wall motion and cyclic strain using cine phase contrast MRI: In vivo validation in the porcine aorta MAGNETIC RESONANCE IN MEDICINE Draney, M. T., Arko, F. R., Alley, M. T., Markl, M., Herfkens, R. J., Pelc, N. J., Zarins, C. K., Taylor, C. A. 2004; 52 (2): 286-295

    Abstract

    Artery wall motion and strain play important roles in vascular remodeling and may be important in the pathogenesis of vascular disease. In vivo observations of circumferentially nonuniform wall motion in the human aorta suggest that nonuniform strain may contribute to the localization of vascular pathology. A velocity-based method to investigate circumferential strain variations was previously developed and validated in vitro; the current study was undertaken to determine whether accurate displacement and strain fields can be calculated from velocity data acquired in vivo. Wall velocities in the porcine thoracic aorta were quantified with PC-MRI and an implanted coil and were then time-integrated to compute wall displacement trajectories and cyclic strain. Displacement trajectories were consistent with observed aortic wall motion and with the displacements of markers in the aortic wall. The mean difference between velocity-based and marker-based trajectory points was 0.1 mm, relative to an average pixel size of 0.4 mm. Propagation of error analyses based on the precision of the computed displacements were used to demonstrate that 10% strain results in a standard deviation of 3.6%. This study demonstrates that it is feasible to accurately quantify strain from low wall velocities in vivo and that the porcine thoracic aorta does not deform uniformly.

    View details for DOI 10.1002/mrm.20137

    View details for Web of Science ID 000223121400008

    View details for PubMedID 15282810

  • Blood flow conditions in the proximal pulmonary arteries and vena cavae: healthy children during upright cycling exercise AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY Cheng, C. P., Herfkens, R. J., Lightner, A. L., Taylor, C. A., Feinstein, J. A. 2004; 287 (2): H921-H926

    Abstract

    Diagnostic testing in patients with congenital heart disease is usually performed supine and at rest, conditions not representative of their typical hemodynamics. Upright exercise measurements of blood flow may prove valuable in the assessment of these patients, but data in normal subjects are first required. With the use of a 0.5-T open magnet, a magnetic resonance-compatible exercise cycle, and cine phase-contrast techniques, time-dependent blood flow velocities were measured in the right (RPA), left (LPA), and main (MPA) pulmonary arteries and superior (SVC) and inferior (IVC) vena cavae of 10 healthy 10- to 14-yr-old subjects. Measurements were made at seated rest and during upright cycling exercise (150% resting heart rate). Mean blood flow (l/min) and reverse flow index were computed from the velocity data. With exercise, RPA and LPA mean flow increased 2.0 +/- 0.5 to 3.7 +/- 0.7 (P < 0.05) and 1.6 +/- 0.4 to 2.9 +/- 0.8 (P < 0.05), respectively. Pulmonary reverse flow index (rest vs. exercise) decreased with exercise as follows: MPA: 0.014 +/- 0.012 vs. 0.006 +/- 0.006 [P = not significant (NS)], RPA: 0.005 +/- 0.004 vs. 0.000 +/- 0.000 (P < 0.05), and LPA: 0.041 +/- 0.019 vs. 0.014 +/- 0.016 (P < 0.05). SVC and IVC flow increased from 1.5 +/- 0.2 to 1.9 +/- 0.6 (P = NS) and 1.6 +/- 0.4 to 4.9 +/- 1.3 (P < 0.05), respectively. A 56/44% RPA/LPA flow distribution at both rest and during exercise suggests blood flow distribution is dominated by distal pulmonary resistance. Reverse flow in the MPA appears to originate solely from the LPA while the RPA is in relative isolation. During seated rest, the SVC-to-IVC venous return ratio is 50/50%. With light/moderate cycling exercise, IVC flow increases by threefold, whereas SVC remains essentially constant.

    View details for DOI 10.1152/ajpheart.00022.2004

    View details for Web of Science ID 000222848000064

    View details for PubMedID 15031121

  • Time-resolved 3-dimensional velocity mapping in the thoracic aorta - Visualization of 3-directional blood flow patterns in healthy volunteers and patients JOURNAL OF COMPUTER ASSISTED TOMOGRAPHY Markl, M., Draney, M. T., Hope, M. D., Levin, J. M., Chan, F. P., Alley, M. T., Pelc, N. J., Herfkens, R. J. 2004; 28 (4): 459-468

    Abstract

    An analysis of thoracic aortic blood flow in normal subjects and patients with aortic pathologic findings is presented. Various visualization tools were used to analyze blood flow patterns within a single 3-component velocity volumetric acquisition of the entire thoracic aortaTime-resolved, 3-dimensional phase-contrast magnetic resonance imaging (3D CINE PC MRI) was employed to obtain complete spatial and temporal coverage of the entire thoracic aorta combined with spatially registered 3-directional pulsatile blood flow velocities. Three-dimensional visualization tools, including time-resolved velocity vector fields reformatted to arbitrary 2-dimensional cut planes, 3D streamlines, and time-resolved 3D particle traces, were applied in a study with 10 normal volunteers. Results from 4 patient examinations with similar scan prescriptions to those of the volunteer scans are presented to illustrate flow features associated with common pathologic findings in the thoracic aorta.Previously reported blood flow patterns in the thoracic aorta, including right-handed helical outflow, late systolic retrograde flow, and accelerated passage through the aortic valve plane, were visualized in all volunteers. The effects of thoracic aortic disease on spatial and temporal blood flow patterns are illustrated in clinical cases, including ascending aortic aneurysms, aortic regurgitation, and aortic dissection.Time-resolved 3D velocity mapping was successfully applied in a study of 10 healthy volunteers and 4 patients with documented aortic pathologic findings and has proven to be a reliable tool for analysis and visualization of normal characteristic as well as pathologic flow features within the entire thoracic aorta.

    View details for Web of Science ID 000222861400005

    View details for PubMedID 15232376

  • Images in cardiovascular medicine. Four-dimensional magnetic resonance velocity mapping in a healthy volunteer with pseudocoarctation of the thoracic aorta. Circulation Hope, M. D., Levin, J. M., Markl, M., Draney, M. T., Alley, M., Herfkens, R. J. 2004; 109 (25): 3221-3222

    View details for PubMedID 15226232

  • Steady-state free precession MR imaging: Improved myocardial tag persistence and signal-to-noise ratio for analysis of myocardial motion RADIOLOGY Markl, M., Reeder, S. B., Chan, F. P., Alley, M. T., Herfkens, R. J., Pelc, N. J. 2004; 230 (3): 852-861

    Abstract

    Tagging with balanced steady-state free-precession (SSFP) magnetic resonance (MR) imaging by using a steady-state storage scheme for myocardial motion analysis was evaluated. Signal-to-noise ratio (SNR), blood-tissue contrast, and tag persistence in volunteers and phantoms showed improved performance of SSFP imaging with tagging compared with that of radiofrequency spoiled gradient-echo (SPGR) MR imaging with tagging. Choice of flip angle with SSFP imaging involved a trade-off among SNR, blood-tissue contrast, and tag persistence. Increased SNR and tag persistence can be achieved simultaneously with SSFP imaging compared with SPGR tagging methods. As a result, the proposed technique may be useful for analysis of diastolic ventricular function.

    View details for DOI 10.1148/radiol.2303030181

    View details for Web of Science ID 000189186500037

    View details for PubMedID 14990847

  • Breast magnetic resonance image screening and ductal lavage in women at high genetic risk for breast carcinoma CANCER Hartman, A. R., Daniel, B. L., Kurian, A. W., Mills, M. A., Nowels, K. W., Dirbas, F. M., Kingham, K. E., Chun, N. M., Herfkens, R. J., Ford, J. M., Plevritis, S. K. 2004; 100 (3): 479-489

    Abstract

    Intensive screening is an alternative to prophylactic mastectomy in women at high risk for developing breast carcinoma. The current article reports preliminary results from a screening protocol using high-quality magnetic resonance imaging (MRI), ductal lavage (DL), clinical breast examination, and mammography to identify early malignancy and high-risk lesions in women at increased genetic risk of breast carcinoma.Women with inherited BRCA1 or BRCA2 mutations or women with a >10% risk of developing breast carcinoma at 10 years, as estimated by the Claus model, were eligible. Patients were accrued from September 2001 to May 2003. Enrolled patients underwent biannual clinical breast examinations and annual mammography, breast MRI, and DL.Forty-one women underwent an initial screen. Fifteen of 41 enrolled women (36.6%) either had undergone previous bilateral oophorectomy and/or were on tamoxifen at the time of the initial screen. One patient who was a BRCA1 carrier had high-grade ductal carcinoma in situ (DCIS) that was screen detected by MRI but that was missed on mammography. High-risk lesions that were screen detected by MRI in three women included radial scars and atypical lobular hyperplasia. DL detected seven women with cellular atypia, including one woman who had a normal MRI and mammogram.Breast MRI identified high-grade DCIS and high-risk lesions that were missed by mammography. DL detected cytologic atypia in a high-risk cohort. A larger screening trial is needed to determine which subgroups of high-risk women will benefit and whether the identification of malignant and high-risk lesions at an early stage will impact breast carcinoma incidence and mortality.

    View details for DOI 10.1002/cncr.11926

    View details for Web of Science ID 000188611400006

    View details for PubMedID 14745863

  • Helical MR: Continuously moving table axial imaging with radial acquisitions MAGNETIC RESONANCE IN MEDICINE Shankaranarayanan, A., Herfkens, R., Hargreaves, B. M., Polzin, J. A., Santos, J. M., Brittain, J. H. 2003; 50 (5): 1053-1060

    Abstract

    A technique for extended field of view MRI is presented. Similar to helical computed tomography, the method utilizes a continuously moving patient table, a 2D axial slice that remains fixed relative to the MRI magnet, and a radial k-space trajectory. A fully refocused SSFP acquisition enables spatial resolution comparable to current clinical protocols in scan times that are sufficiently short to allow a reasonable breathhold duration. RF transmission and signal reception are performed using the RF body coil and the images are reconstructed in real time. Experimental results are presented that illustrate the technique's ability to resolve small structures in the table-motion direction. Simulation experiments to study the steady-state response of the fully refocused SSFP acquisition during continuous table motion are also presented. Finally, whole body images of healthy volunteers demonstrate the high image quality achieved using the helical MRI approach.

    View details for DOI 10.1002/mrm.10621

    View details for Web of Science ID 000186326400019

    View details for PubMedID 14587016

  • Abdominal aortic hemodynamic conditions in healthy subjects aged 50-70 at rest and during lower limb exercise: in vivo quantification using MR1 ATHEROSCLEROSIS Cheng, C. P., Herfkens, R. J., Taylor, C. A. 2003; 168 (2): 323-331

    Abstract

    The prevalence of atherosclerosis in the abdominal aorta increases with age and is hypothesized to be related to adverse hemodynamic conditions including flow recirculation and low wall shear stress. Exercise has been shown to modulate these adverse conditions observed in the infrarenal aorta of healthy young subjects at rest. A custom magnetic resonance (MR)-compatible stationary cycle, an open MRI, and custom image processing software were used to quantify hemodynamic conditions in the abdominal aorta at rest and during cycling exercise in healthy subjects aged 50-70 years. The subjects increased their heart rate from 63+/-8 bpm at rest to 95+/-12 bpm during cycling exercise. Supraceliac blood flow increased from 2.3+/-0.4 to 6.0+/-1.4 l/min (P<0.001) and infrarenal flow increased from 0.9+/-0.3 to 4.9+/-1.7 l/min (P<0.001) from rest to exercise. Wall shear stress increased from 2.0+/-0.7 to 7.3+/-2.4 dynes/cm(2) at the supraceliac level (P<0.001) and 1.4+/-0.8 to 16.5+/-5.1 dynes/cm(2) at the infrarenal level (P<0.001) from rest to exercise. Flow and shear oscillations present at rest were eliminated during exercise. At rest, these older subjects experienced lower mean wall shear stress at the supraceliac level of the aorta and greater oscillations in wall shear stress as compared to a group of younger subjects (23.6+/-2.2 years). Compared to the younger subjects, the older subjects also experienced greater increases in mean wall shear stress and greater decreases in wall shear stress oscillations from rest to exercise.

    View details for DOI 10.1016/S0021-9150(03)00099-6

    View details for Web of Science ID 000183784900015

    View details for PubMedID 12801616

  • Inferior vena caval hemodynamics quantified in vivo at rest and during cycling exercise using magnetic resonance imaging AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY Cheng, C. P., Herfkens, R. J., Taylor, C. A. 2003; 284 (4): H1161-H1167

    Abstract

    Compared with the abdominal aorta, the hemodynamic environment in the inferior vena cava (IVC) is not well described. With the use of cine phase-contrast magnetic resonance imaging (MRI) and a custom MRI-compatible cycle in an open magnet, we quantified mean blood flow rate, wall shear stress, and cross-sectional lumen area in 11 young normal subjects at the supraceliac and infrarenal levels of the aorta and IVC at rest and during dynamic cycling exercise. Similar to the aorta, the IVC experienced significant increases in blood flow and wall shear stress as a result of exercise, with greater increases in the infrarenal level compared with the supraceliac level. At the infrarenal level during resting conditions, the IVC experienced higher mean flow rate than the aorta (1.2 +/- 0.5 vs. 0.9 +/- 0.4 l/min, P < 0.01) and higher mean wall shear stress than the aorta (2.0 +/- 0.6 vs. 1.3 +/- 0.6 dyn/cm(2), P < 0.005). During exercise, wall shear stress remained higher in the IVC compared with the aorta, although not significantly. It was also observed that, whereas the aorta tapers inferiorly, the IVC tapers superiorly from the infrarenal to the supraceliac location. The hemodynamic and anatomic data of the IVC acquired in this study add to our understanding of the venous circulation and may be useful in a clinical setting.

    View details for DOI 10.1152/ajpheart.00641.2002

    View details for Web of Science ID 000181425900016

    View details for PubMedID 12595296

  • Time-resolved three-dimensional phase-contrast MRI JOURNAL OF MAGNETIC RESONANCE IMAGING Markl, M., Chan, F. P., Alley, M. T., Wedding, K. L., Draney, M. T., Elkins, C. J., Parker, D. W., Wicker, R., Taylor, C. A., Herfkens, R. J., Pelc, N. J. 2003; 17 (4): 499-506

    Abstract

    To demonstrate the feasibility of a four-dimensional phase contrast (PC) technique that permits spatial and temporal coverage of an entire three-dimensional volume, to quantitatively validate its accuracy against an established time resolved two-dimensional PC technique to explore advantages of the approach with regard to the four-dimensional nature of the data.Time-resolved, three-dimensional anatomical images were generated simultaneously with registered three-directional velocity vector fields. Improvements compared to prior methods include retrospectively gated and respiratory compensated image acquisition, interleaved flow encoding with freely selectable velocity encoding (venc) along each spatial direction, and flexible trade-off between temporal resolution and total acquisition time.The implementation was validated against established two-dimensional PC techniques using a well-defined phantom, and successfully applied in volunteer and patient examinations. Human studies were performed after contrast administration in order to compensate for loss of in-flow enhancement in the four-dimensional approach.Advantages of the four-dimensional approach include the complete spatial and temporal coverage of the cardiovascular region of interest and the ability to obtain high spatial resolution in all three dimensions with higher signal-to-noise ratio compared to two-dimensional methods at the same resolution. In addition, the four-dimensional nature of the data offers a variety of image processing options, such as magnitude and velocity multi-planar reformation, three-directional vector field plots, and velocity profiles mapped onto selected planes of interest.

    View details for DOI 10.1002/jmri.10272

    View details for Web of Science ID 000182453200016

    View details for PubMedID 12655592

  • Dynamic exercise imaging with an MR-Compatible stationary cycle within the general electric open magnet MAGNETIC RESONANCE IN MEDICINE Cheng, C. P., Schwandt, D. F., Topp, E. L., Anderson, J. H., Herfkens, R. J., Taylor, C. A. 2003; 49 (3): 581-585

    Abstract

    Many cases of muscular ischemia do not manifest without increased metabolic demand. Hence, diagnosis of intermittent claudication often requires inducing physiologic challenge, such as by exercise. Cine phase-contrast MRI can concurrently acquire cross-sectional vascular anatomy and through-plane blood velocities, enabling blood flow rate quantification. An MR-compatible stationary cycle was designed, constructed, and tested for flow quantification in large arteries during lower-limb exercise in a General Electric Signa SP 0.5 T open magnet. The cycle demonstrated smooth cycling during image acquisition, has freewheeling capability, is adjustable for subject size and strength, and can quantify workload. A healthy 59-year-old male was imaged at the supraceliac and infrarenal levels of the abdominal aorta at rest and during exercise. An exercise workload of 47.9 W was achieved. His heart rate increased from 52 to 78 bpm, supraceliac flow increased from 1.7 to 3.7 L/min, and infrarenal flow increased from 0.4 to 3.2 L/min from rest to exercise.

    View details for DOI 10.1002/mrm.10364

    View details for Web of Science ID 000181297200024

    View details for PubMedID 12594764

  • Comparison of abdominal aortic hemodynamics between men and women at rest and during lower limb exercise JOURNAL OF VASCULAR SURGERY Cheng, C. P., Herfkens, R. J., Taylor, C. A. 2003; 37 (1): 118-123

    Abstract

    Biologic variations between men and women have been hypothesized to contribute to the differences in atherosclerosis epidemiology of the two genders. Hemodynamics are also hypothesized to play an important role in the localization of atherosclerosis in the abdominal aorta. However, the hemodynamics of men and women have not been compared at this location at rest or during lower limb exercise conditions.A magnetic resonance-compatible exercise bicycle, magnetic resonance imaging techniques, and custom data processing software were used to quantify blood flow rate, wall shear stress, and oscillations in flow and wall shear stress at the supraceliac and infrarenal levels of the abdominal aorta of young healthy men and women at rest and during lower limb exercise.Heart rate increased from 73 +/- 6.2 bpm at rest to 110 +/- 8.8 bpm during exercise (P <.0001). No statistical differences were found at the infrarenal level for mean blood flow rate (men, 0.9 +/- 0.4 L/min; women, 0.8 +/- 0.4 L/min) or mean wall shear stress (men, 1.2 +/- 0.5 dynes/cm(2); women, 1.4 +/- 0.7 dynes/cm(2)) at rest or mean blood flow rate (men, 5.9 +/- 1.3 L/min; women, 5.2 +/- 0.8 L/min) or mean wall shear stress (men, 5.1 +/- 0.8 dynes/cm(2); women, 5.4 +/- 2.1 dynes/cm(2)) during exercise. Also, no differences were seen in temporal flow and wall shear stress oscillations between men and women at rest or during exercise. Similarly, no significant hemodynamic differences were found between the genders at the supraceliac level.These similarities suggest that hemodynamics may not play a significant role in abdominal aortic disease differentiation between the genders and that biologic factors may be more important.

    View details for DOI 10.1067/mva.2002.107

    View details for Web of Science ID 000180465200027

    View details for PubMedID 12514587

  • Quantification of vessel wall cyclic strain using cine phase contrast magnetic resonance imaging ANNALS OF BIOMEDICAL ENGINEERING Draney, M. T., Herfkens, R. J., Hughes, T. J., Pelc, N. J., Wedding, K. L., Zarins, C. K., Taylor, C. A. 2002; 30 (8): 1033-1045

    Abstract

    In vivo quantification of vessel wall cyclic strain has important applications in physiology and disease research and the design of intravascular devices. We describe a method to calculate vessel wall strain from cine PC-MRI velocity data. Forward-backward time integration is used to calculate displacement fields from the velocities, and cyclic Green-Lagrange strain is computed in segments defined by the displacements. The method was validated using a combination of in vitro cine PC-MRI and marker tracking studies. Phantom experiments demonstrated that wall displacements and strain could be calculated accurately from PC-MRI velocity data, with a mean displacement difference of 0.20 +/- 0.16 mm (pixel size 0.39 mm) and a mean strain difference of 0.01 (strain extent 0.20). A propagation of error analysis defined the relationship between the standard deviations in displacements and strain based on original segment length and strain magnitude. Based on the measured displacement standard deviation, strain standard deviations were calculated to be 0.015 (validation segment length) and 0.045 (typical segment length). To verify the feasibility of using this method in vivo, cyclic strain was calculated in the thoracic aorta of a normal human subject. Results demonstrated nonuniform deformation and circumferential variation in cyclic strain, with a peak average strain of 0.08 +/- 0.11.

    View details for DOI 10.1114/1.1513566

    View details for Web of Science ID 000179121200005

    View details for PubMedID 12449764

  • Intraoperative MR imaging: Can image guidance improve therapy? ACADEMIC RADIOLOGY Daniel, B., Herfkens, R. 2002; 9 (8): 875-877

    View details for Web of Science ID 000177347900001

    View details for PubMedID 12186434

  • MR imaging features of infiltrating lobular carcinoma of the breast: Histopathologic correlation AMERICAN JOURNAL OF ROENTGENOLOGY Qayyum, A., Birdwell, R. L., Daniel, B. L., Nowels, K. W., Jeffrey, S. S., Agoston, T. A., Herfkens, R. J. 2002; 178 (5): 1227-1232

    Abstract

    Our study aimed to correlate the dynamic contrast-enhanced MR appearance of infiltrating lobular carcinoma of the breast with histopathologic findings.We retrospectively reviewed the high-resolution, fat-suppressed and dynamic contrast-enhanced MR images of 13 of 20 women diagnosed with pathologically proven infiltrating lobular carcinoma of the breast. Twelve of the 13 women presented with breast symptoms and underwent mammography. Five of the women also had breast sonography. MR imaging was performed for evaluation of disease extent before the patients underwent modified radical mastectomy (n = 11) or lumpectomy (n = 2). Three experienced radiologists reviewed the MR scans. The tumor pattern types described on imaging were correlated with a detailed analysis of the pathology.We found three patterns of infiltrating lobular carcinoma on MR imaging. The tumor pattern on imaging correlated with pathologic tumor morphology. We found the following patterns of infiltrating lobular carcinoma: a solitary mass with irregular margins (n = 4) that corresponded to the same appearance at pathology; multiple lesions, either connected by enhancing strands (n = 6) or separated by nonenhancing intervening tissue (n = 2), that correlated with the pathologic appearance of noncontiguous tumor foci, with malignant cells streaming in single-file fashion in the breast stroma or small tumor aggregates separated by normal tissue; and enhancing septa only, which were correlated with the histopathologic appearance of tumor cells streaming in the breast stroma (n = 1).Infiltrating lobular carcinoma may be detected on MR imaging as solitary or multiple lesions that correspond to tumor morphology on pathologic examination. The appearance of multiple lesions or of enhancing fibroglandular breast elements on MR imaging is suggestive of infiltrating lobular carcinoma.

    View details for Web of Science ID 000175077200034

    View details for PubMedID 11959737

  • In vivo quantification of blood flow and wall shear stress in the human abdominal aorta during lower limb exercise ANNALS OF BIOMEDICAL ENGINEERING Taylor, C. A., Cheng, C. P., Espinosa, L. A., Tang, B. T., Parker, D., Herfkens, R. J. 2002; 30 (3): 402-408

    Abstract

    Magnetic resonance (MR) imaging techniques and a custom MR-compatible exercise bicycle were used to measure, in vivo, the effects of exercise on hemodynamic conditions in the abdominal aorta of eleven young, healthy subjects. Heart rate increased from 73 +/- 6.2 beats/min at rest to 110 +/- 8.8 beats/min during exercise (p<0.0001). The total blood flow through the abdominal aorta increased from 2.9 +/- 0.6 L/min at rest to 7.2 +/- 1.4 L/min during exercise (p <0.0005) while blood flow to the digestive and renal circulations decreased from 2.1 +/- 0.5 L/min at rest to 1.6 +/- 0.7 L/min during exercise (p<0.01). Infrarenal blood flow increased from 0.9 +/- 0.4 L/min at rest to 5.6 +/- 1.1 L/min during exercise (p<0.0005). Wall shear stress increased in the supraceliac aorta from 3.5 +/- 0.8 dyn/cm2 at rest to 6.2 +/- 0.5 dyn/cm2 during exercise (p<0.0005) and increased in the infrarenal aorta from 1.3 +/- 0.8 dyn/cm2 at rest to 5.2 +/- 1.3 dyn/cm2 during exercise (p<0.0005).

    View details for DOI 10.1114/1.1476016

    View details for Web of Science ID 000175849500012

    View details for PubMedID 12051624

  • Magnetic resonance imaging for the evaluation of hydronephrosis, reflux and renal scarring in children JOURNAL OF UROLOGY Rodriguez, L. V., Spielman, D., Herfkens, R. J., Shortliffe, L. D. 2001; 166 (3): 1023-1027

    Abstract

    We studied the effectiveness of magnetic resonance imaging (MRI) for evaluating hydronephrosis, differential renal function, vesicoureteral reflux and renal scarring in children.A total of 16 patients with hydronephrosis were evaluated with MRI. Coronal T1 and axial T1 and T2-weighted images were obtained before and after the administration of intravenous contrast material. Patients with vesicoureteral reflux underwent magnetic resonance voiding cystourethrography. Differential renal function was estimated from differential parenchymal volumes determined from MRI using computer software. The results were compared to standard imaging modalities.A total of 19 MRI studies were performed in 16 patients, including 3 for ureteropelvic junction obstruction, 11 for vesicoureteral reflux and 2 for other conditions. MRI provided the best anatomic detail and clear corticomedullary differentiation. MRI identified renal scarring and cortical thinning in 8 cases, while mercaptoacetyltriglycine 3 scans did not show any renal scarring and single photon emission computerized tomography-dimercapto-succinic acid nuclear scans diagnosed only 4 of 5 cases. There was good correlation between differential function obtained from nuclear scans and differential parenchymal volumes obtained from MRI (correlation coefficient 0.86, r2 = 0.74). Magnetic resonance voiding cystourethrography diagnosed reflux in 4 of 5 patients in whom vesicoureteral reflux was previously documented by standard voiding cystourethrography.MRI provides an alternative for the evaluation of hydronephrosis in children by combining the information provided by functional and anatomic nuclear scans, voiding cystourethrography and ultrasonography in a single study without ionizing radiation. MRI appears to be as good as existing modalities in the evaluation of renal scarring and cortical thinning.

    View details for Web of Science ID 000170453600083

    View details for PubMedID 11490289

  • 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

  • Intensity-modulated parametric mapping for simultaneous display of rapid dynamic and high-spatial-resolution breast MR imaging data RADIOGRAPHICS Agoston, A. T., Daniel, B. L., Herfkens, R. J., Ikeda, D. M., Birdwell, R. L., Heiss, S. G., Sawyer-Glover, A. M. 2001; 21 (1): 217-226

    Abstract

    Contrast material-enhanced magnetic resonance (MR) imaging of the breast has variable specificity for differentiation of breast cancer from other enhancing conditions. Two principal strategies to improve its specificity are rapid dynamic MR imaging and high-spatial-resolution MR imaging. A method was developed of combining contemporaneously acquired dynamic and high-spatial-resolution MR imaging data into a single integrated display. Whole-breast rapid dynamic data were condensed into a color map by using pharmacokinetic analysis. The pharmacokinetic results were combined with the high-spatial-resolution images with a new technique that preserves underlying morphologic details. This new method was evaluated by five radiologists for eight breast lesions, and the results were compared with those of the standard method of overlaying parametric map data. The radiologists' ratings showed a statistically significant preference for the intensity-modulated parametric map display method over the overlaid parametric display method for 10 of the 12 evaluation criteria. The new method enabled simultaneous visualization of pharmacokinetic and morphologic information, facilitated assessment of lesion extent, and improved the suppression of noise in the pharmacokinetic data. The ability to simultaneously assess both dynamic and high-spatial-resolution features may ultimately improve the specificity of breast MR imaging.

    View details for Web of Science ID 000170928100018

    View details for PubMedID 11158656

  • Phase-contrast cine MR angiography detection of thoracic aortic dissection INTERNATIONAL JOURNAL OF CARDIAC IMAGING Silverman, J. M., Raissi, S., Tyszka, J. M., Trento, A., Herfkens, R. J. 2000; 16 (6): 461-470

    Abstract

    To assess prospectively the accuracy of phase-contrast cine MR angiography in the detection of thoracic aortic dissection with operative correlation.One hundred and ninety-seven symptomatic patients suspected of having thoracic aortic dissection or aneurysm as well as 13 patients suspected of having thoracic aortic coarctation and 20 asymptomatic normals (as controls) were examined prospectively with phase-contrast cine MR angiography on a 1.5-T MR imager. Seventy-eight of these patients had operative correlation, and only these 78 patients were included in the statistical analysis.There were 51 true positive and 27 true negative findings of thoracic aortic dissection in this study for an accuracy of 100%.Phase-contrast cine MR angiography is an accurate non-invasive imaging technique for evaluating patients suspected of having thoracic aortic dissection.

    View details for Web of Science ID 000169333800007

    View details for PubMedID 11482712

  • Partial fat-saturated contrast-enhanced three-dimensional MR angiography compared with non-fat-saturated and conventional fat-saturated MR angiography RADIOLOGY Hilfiker, P. R., Herfkens, R. J., Heiss, S. G., Alley, M. T., Fleischmann, D., Pelc, N. J. 2000; 216 (1): 298-303

    Abstract

    Abdominal three-dimensional magnetic resonance angiography was performed in 35 patients in the equilibrium phase without fat saturation, with conventional fat saturation, and with fast partial fat saturation. Qualitative and quantitative evaluation demonstrated significantly better vessel visualization with both fat-saturated techniques. The partial fat-saturated technique provided water-specific images within a breath hold, reducing motion artifacts significantly.

    View details for Web of Science ID 000087829500044

    View details for PubMedID 10887265

  • Single-shot fluid attenuated inversion recovery (FLAIR) magnetic resonance imaging of the bladder JOURNAL OF MAGNETIC RESONANCE IMAGING Daniel, B. L., Shimakawa, A., Blum, M. R., Herfkens, R. J. 2000; 11 (6): 673-677

    Abstract

    The purpose of this study was to reduce artifacts and increase imaging speed in fluid-attenuated inversion recovery (FLAIR) imaging of the urinary bladder. An existing half-Fourier, single-shot fast spin-echo imaging sequence was modified to allow presaturation with a non-slice-selective inversion recovery pulse (NSI SSFLAIR). Four independent, blinded readers rated severity of bladder artifacts and image quality in six normal male volunteers. NSI SSFLAIR effectively suppressed bladder urine signal in all six cases using a TI of 2900-3100 msec. Although NSI SSFLAIR images were noisier than standard fast spin-echo images, imaging time was only 10 seconds per slice location. Furthermore, perceived image sharpness was only minimally reduced, and conspicuity of the seminal vesicles and peripheral zone of the prostate were nearly equivalent. NSI SSFLAIR provides rapid T2-weighted imaging of the bladder wall and perivesicular tissues with nearly complete negation of signal from urine in the bladder.

    View details for Web of Science ID 000171294400014

    View details for PubMedID 10862067

  • Dynamic breast MRI with spiral trajectories: 3D versus 2D JOURNAL OF MAGNETIC RESONANCE IMAGING Yen, Y. F., Han, K. F., Daniel, B. L., Heiss, S., Birdwell, R. L., Herfkens, R. J., Sawyer-Glover, A. M., Glover, G. H. 2000; 11 (4): 351-359

    Abstract

    A three-dimensional (3)D spiral sequence was developed for dynamic breast magnetic resonance (MR) imaging with much improved image quality. Partial Z phase encoding was applied to obtain thinner slices for a coverage of the whole breast. Comparison between the 3D and a previously developed multi-slice 2D spiral sequences was performed on ten healthy volunteers without contrast and five breast patients with gadolinium-diethylene triamine pentaacetic acid (Gd-DTPA). The 3D spiral images had significantly less off-resonance blurring and spiral artifacts. With a small compromise on temporal resolution (7.7 seconds in 2D and 10.6 seconds in 3D), we obtained 32 interpolated 3-5 mm slices (with 20 Z phase encodes) for a full coverage of 10-16 cm breast with the same 1 x 1 mm2 in-plane resolution as the 2D sequence, which had 12 8-13 mm slices. Contrast between glandular and soft tissue in normal breasts was increased by about 25%. The reduced repetition time in the 3D spiral acquisition led to an increased Gd-enhanced signal. The difference between the enhancement of malignant and benign lesions increased by sevenfold. We expect that this new development could lead to improved specificity in characterizing breast lesions using MR imaging.

    View details for Web of Science ID 000087572700002

    View details for PubMedID 10767063

  • Three-dimensional cardiac cine magnetic resonance imaging with an ultrasmall superparamagnetic iron oxide blood pool agent (NC100150) JOURNAL OF MAGNETIC RESONANCE IMAGING Amano, Y., Herfkens, R. J., Shifrin, R. Y., Alley, M. T., Pelc, N. J. 2000; 11 (2): 81-86

    Abstract

    The purpose of this study was to assess image quality of three-dimensional (3D) cardiac cine magnetic resonance (MR) imaging before and after administration of a T1-shortening ultrasmall superparamagnetic iron oxide blood pool agent (NC100150). 3D cardiac cine MR imaging was performed in 13 volunteers using a radiofrequency-spoiled cardiac-gated 3D cine gradient-echo sequence with short repetition and echo times. Compared with precontrast images, postcontrast images showed no enhancement in fat and skeletal muscle, moderate enhancement in myocardium, and significant enhancement in ventricular cavity. After contrast injection, the signal ratio of the ventricular chamber to the myocardium significantly increased, and dramatic improvements were seen in the quality of the cineangiographic images and the depiction of cardiac valves. This quantitative study has shown that 3D cardiac cine MR imaging using a blood pool agent provided MR ventriculography and cineangiography with excellent image quality.

    View details for Web of Science ID 000086078100002

    View details for PubMedID 10713938

  • Characterization of breast lesion morphology with delayed 3DSSMT: An adjunct to dynamic breast MRI JOURNAL OF MAGNETIC RESONANCE IMAGING Leong, C. S., Daniel, B. L., Herfkens, R. J., Birdwell, R. L., Jeffrey, S. S., Ikeda, D. M., Sawyer-Glover, A. M., Glover, G. H. 2000; 11 (2): 87-96

    Abstract

    The purpose of the study was to determine the sensitivity and specificity of various morphologic criteria in distinguishing malignant from benign breast lesions using a new sequence (3DSSMT) performed immediately after dynamic breast MRI. 3DSSMT combines a water-selective spectral-spatial excitation and an on-resonance magnetization transfer pulse with three-dimensional spoiled gradient-echo imaging. Morphologic features of 87 pathologically confirmed lesions were analyzed. The presence of either skin thickening, or a combination of a spiculated or microlobulated border, with a rim, ductal, linear, or clumped enhancement pattern was 94% specific and 54% sensitive for malignancy. Conversely, the presence of either a perfectly smooth border, a well-defined margin, non-enhancing internal septations, or a macrolobulated border was 97% specific and 35% sensitive for a benign diagnosis. In conclusion, delayed 3DSSMT discriminates a significant number of benign and malignant breast lesions; it has the potential to improve the diagnostic accuracy of dynamic breast MRI.

    View details for Web of Science ID 000086078100003

    View details for PubMedID 10713939

  • Silicone breast implant rupture: Pitfalls of magnetic resonance imaging and relative efficacies of magnetic resonance, mammography, and ultrasound PLASTIC AND RECONSTRUCTIVE SURGERY Ikeda, D. M., Borofsky, H. B., Herfkens, R. J., Sawyer-Glover, A. M., Birdwell, R. L., Glover, G. H. 1999; 104 (7): 2054-2062

    Abstract

    The objective of this study was to evaluate the relative efficacies of magnetic resonance (MR) imaging, ultrasonography, and mammography in implant rupture detection and to illustrate pitfalls in MR image interpretation. Thirty patients referred by plastic surgeons with suspected breast implant rupture were prospectively evaluated using MR, ultrasonography, and mammography. Imaging examinations were interpreted independently and blindly for implant rupture and correlated to operative findings. Surgical correlation in 16 patients (53 percent) with 31 implants showed 13 (42 percent) were intact, 5 (16 percent) had severe gel bleed, and 13 (42 percent) were ruptured. MR sensitivity was 100 percent and specificity was 63 percent. Accuracy for rupture was 81 percent with MR, higher than with ultrasonography and mammography (77 and 59 percent, respectively). We describe a specific pitfall in MR interpretation, the "rat-tail" sign, composed of a medial linear extension of silicone along the chest wall. Seen in eight cases (four intact, three ruptures, one gel bleed), the rat-tail sign may lead to misdiagnosis of implant rupture if seen in isolation. Magnetic resonance imaging is more accurate and sensitive than ultrasonography and mammography in detecting breast implant rupture. We describe a new sign (rat-tail sign) composed of medial compression of the implant simulating silicone extrusion as a potential false-positive MR finding for rupture. This article presents clinical experience with magnetic resonance, mammography, and ultrasound in the diagnosis of implant rupture and defines and illustrates potential pitfalls of MR interpretation, including the new rat-tail sign.

    View details for Web of Science ID 000083854900017

    View details for PubMedID 11149768

  • Glenohumeral relationships during physiologic shoulder motion and stress testing: Initial experience with open MR imaging and active imaging-plane registration RADIOLOGY Beaulieu, C. F., Hodge, D. K., Bergman, A. G., Butts, K., Daniel, B. L., Napper, C. L., Darrow, R. D., Dumoulin, C. L., Herfkens, R. J. 1999; 212 (3): 699-705

    Abstract

    To test the hypotheses that open dynamic magnetic resonance (MR) imaging can (a) be used to evaluate and define normal shoulder motion in active joint motion and muscle contraction and (b) be used in conjunction with physical examination.With an open-configuration, 0.5-T MR imaging system and active image-plane tracking, 10 shoulders were studied in five asymptomatic subjects to establish normal patterns of glenohumeral motion during abduction and adduction and internal and external rotation. Preliminary studies of physical examination during MR imaging, in which a physician examiner applied mechanical force to the humeral head, were also performed.During abduction and adduction and internal and external rotation maneuvers with active subjects muscle contraction, the humeral head remained precisely centered on the glenoid fossa in all asymptomatic subjects, which is in agreement with findings of previous radiographic studies. Application of force to the humeral head by an examiner was associated with as much as 6 mm of anterior translation and 13 mm of posterior translation.Dynamic MR imaging of the glenohumeral joint is possible over a wide range of physiologic motion in vertically open systems. Use of an MR tracking coil enabled accurate tracking of the anatomy of interest. These preliminary measurements of normal glenohumeral motion patterns begin to establish normal ranges of motion and constitute a necessary first step in characterizing pathologic motion in patients with common clinical problems such as instability and impingement.

    View details for Web of Science ID 000082196600016

    View details for PubMedID 10478235

  • A multisite Phase III study of the safety and efficacy of a new manganese chloride-based gastrointestinal contrast agent for MRI of the abdomen and pelvis JOURNAL OF MAGNETIC RESONANCE IMAGING Small, W. C., DeSimone-Macchi, D., Parker, J. R., Sukerkar, A., Hahn, P. F., Rubin, D. L., Zelch, J. V., Kuhlman, J. E., Outwater, E. K., Weinreb, J. C., Brown, J. J., De Lange, E. E., Woodward, P. J., Arildsen, R., Foster, G. S., Runge, V. M., Aisen, A. M., Muroff, L. R., Thoeni, R. F., Parisky, Y. R., Tanenbaum, L. N., TOTTERMAN, S., Herfkens, R. J., Knudsen, J., Laster, R. E., Duerinckx, A., Stillman, A. E., Spritzer, C. E., Saini, S., Rofsky, N. M., Bernardino, M. E. 1999; 10 (1): 15-24

    Abstract

    The purpose of this study was to evaluate the safety and efficacy of a manganese chloride-based oral magnetic resonance (MR) contrast agent during a Phase III multisite clinical trial. Two hundred seventeen patients were enrolled who were already scheduled for MRI of the abdomen and/or pelvis. In this group of patients, it was postulated that the use of an oral agent would better allow discrimination of pathology from bowel. Patients with known gastrointestinal pathology including peptic ulcer disease, inflammatory bowel disease, obstruction, or perforation were excluded to minimize confounding variables that could affect the safety assessment. Of these 217 patients, 18 received up to 900 mL of placebo, and 199 patients were given up to 900 mL of a manganese chloride-based oral contrast agent, LumenHance (Bracco Diagnostics, Inc.). Safety was determined by comparing pre- and post-dose physical examinations, vital signs, and laboratory examinations and by documenting adverse events. Efficacy was assessed by unblinded site investigators and two blinded reviewers who compared pre- and post-dose T1- and T2-weighted MRI scans of the abdomen and/or pelvis. In 111 (57%) of the 195 cases evaluated for efficacy by site investigators (unblinded readers), MRI after LumenHance provided additional diagnostic information. Increased information was found by two blinded readers in 52% and 51% of patients, respectively. In 44/195 cases (23%) unblinded readers felt the additional information would have changed patient diagnosis and in 50 patients (26%), it would have changed management and/or therapy. Potential changes in patient diagnosis or management/therapy were seen by the two blinded readers in 8-20% of patients. No clinically significant post-dose laboratory changes were seen. Forty-eight patients (24%) receiving LumenHance and four patients (22%) receiving placebo experienced one or more adverse events. Gastrointestinal tract side effects were most common, seen in 29 (15%) of LumenHance patients and in 3 (17%) of the placebo patients. LumenHance is a safe and efficacious oral gastrointestinal contrast agent for MRI of the abdomen and pelvis.

    View details for Web of Science ID 000081199600003

    View details for PubMedID 10398973

  • Fast 3D cardiac cine MR imaging JOURNAL OF MAGNETIC RESONANCE IMAGING Alley, M. T., Napel, S., Amano, Y., Paik, D. S., Shifrin, R. Y., Shimakawa, A., Pelc, N. J., Herfkens, R. J. 1999; 9 (5): 751-755

    Abstract

    We describe a technique for three-dimensional cine MR imaging. By using short repetition times (TR) and interleaved slice encoding, volumetric cine data can be acquired throughout the cardiac cycle with a temporal resolution of approximately 80 msec. A T1-shortening agent is used to produce contrast between blood and myocardium. A comparison between the acquisition times of this and several other two-dimensional techniques is presented.

    View details for Web of Science ID 000083418000021

    View details for PubMedID 10331775

  • MR-guided transjugular portosystemic shunt placement in a swine model JOURNAL OF VASCULAR AND INTERVENTIONAL RADIOLOGY Kee, S. T., Rhee, J. S., Butts, K., Daniel, B., Pauly, J., Kerr, A., O'Sullivan, G. J., Sze, D. Y., Razavi, M. K., Semba, C. P., Herfkens, R. J., Dake, M. D. 1999; 10 (5): 529-535

    Abstract

    To evaluate the performance of portal venous puncture with use of magnetic resonance (MR) guidance, and to place a transjugular intrahepatic portosystemic shunt (TIPS) in a swine model.A study of 12 swine was performed to evaluate the ability of interventional MR imaging to guide portal vein puncture and TIPS placement. Six swine had catheters placed in the right hepatic vein under C-arm fluoroscopy. A nitinol guide wire was left in the vein and the animals were then moved into an open configuration MR imaging unit. A TIPS needle set was used to puncture the portal vein using MR fluoroscopy. The animals were transferred to the C-arm, and venography confirmed portal vein puncture. A follow-up study was performed in six additional swine to place a TIPS using only MR imaging guidance. MR tracking was used to advance a catheter from the right atrium into the inferior vena cava. Puncture of the portal vein was performed and a nitinol stent was placed, bridging the hepatic parenchyma. MR venogram confirmed placement.Successful portal vein puncture was achieved in all animals. The number of punctures required decreased from 12 in the first animal to a single puncture in the last eight swine. A stent was successfully placed across the hepatic tract in all six swine.Real-time MR imaging proved to be a feasible method to guide portal vein puncture and TIPS placement in pigs.

    View details for Web of Science ID 000084345500001

  • Breast disease: Dynamic spiral MR imaging RADIOLOGY Daniel, B. L., Yen, Y. F., Glover, G. H., Ikeda, D. M., Birdwell, R. L., Sawyer-Glover, A. M., Black, J. W., Plevritis, S. K., Jeffrey, S. S., Herfkens, R. J. 1998; 209 (2): 499-509

    Abstract

    To compare various subjective, empiric, and pharmacokinetic methods for interpreting findings at dynamic magnetic resonance (MR) imaging of the breast.Dynamic spiral breast MR imaging was performed in 52 women suspected of having or with known breast disease. Gadolinium-enhanced images were obtained at 12 locations through the whole breast every 7.8 seconds for 8.5 minutes after bolus injection of contrast material. Time-signal intensity curves from regions of interest corresponding to 57 pathologically proved lesions were analyzed by means of a two-compartment pharmacokinetic model, and the diagnostic performance of various parameters was analyzed.Findings included invasive carcinoma in 17 patients, isolated ductal carcinoma in situ (DCIS) in six, and benign lesions in 34. Although some overlap between carcinomas and benign diagnoses was noted for all parameters, receiver operating characteristic analysis indicated that the exchange rate constant had the greatest overall ability to discriminate benign and malignant disease. The elimination rate constant and washout were the most specific parameters. The exchange rate constant, wash-in, and extrapolation point were the most sensitive parameters. DCIS was not consistently distinguished from benign disease with any method.Dynamic spiral breast MR imaging proved an excellent method with which to collect contrast enhancement data rapidly enough that accurate comparisons can be made between many analytic methods.

    View details for Web of Science ID 000076618000034

    View details for PubMedID 9807580

  • Successful transplantation of adult-sized kidneys into infants requires maintenance of high aortic blood flow TRANSPLANTATION Salvatierra, O., Singh, T., Shifrin, R., Conley, S., Alexander, S., Tanney, D., Lemley, K., Sarwal, M., Mackie, F., Alfrey, E., Orlandi, P., Zarins, C., Herfkens, R. 1998; 66 (7): 819-823

    Abstract

    Nationally, results of renal transplantation in infants are inferior to those in older children and adults. Within the infant group, best results are obtained with adult-sized kidneys (ASKs) rather than size-compatible pediatric kidneys. However, transplantation of ASKs into infants has an increased risk of acute tubular necrosis and graft loss from vascular thrombosis and primary nonfunction. The aim of this study was to define and understand the hemodynamic changes induced by ASK transplantation, so that outcomes of transplantation in infants can be improved.Nine hemodynamically stable and optimally hydrated infants were studied under a controlled sedation with cine phase-contrast magnetic resonance at three time periods: before transplantation, 8-12 days after transplantation, and 4-6 months after transplantation. Cross-sectional images of both the infant aorta and the adult transplant renal artery were obtained and blood flow was quantitated. Renal volumes were also obtained, and expected renal artery blood flow based on early posttransplant volume was calculated. In addition, renal artery blood flow was determined in 10 in situ native adult kidneys prior to donor nephrectomy. Supplemental nasogastric or gastrostomy tube feeding was carried out during the blood flow study period to optimize intravascular volume.Mean infant aortic blood flows were 331+/-148 ml/min before transplantation, 761+/-272 ml/ min at 8-12 days after transplantation (P=0.0006 with pretransplant flow), and 665+/-138 ml/min at 4-6 months after transplantation (P=0.0001 with pretransplant flow). Mean transplanted renal artery flows were 385+/-158 ml/min at 8-12 days and 296+/-113 ml/min at 4-6 months after transplantation. Transplanted renal artery flows were less than prenephrectomy in situ donor renal artery blood flow (618+/-130 ml/min; P=0.02 and P=0.0003) and expected normal renal artery blood flow (666+/-87 ml/min; P=0.003 and P=0.001) at both 8-12 days and 4-6 months after transplantation. A 26% reduction in renal volume (P=0.003) occurred between the two postoperative time periods, and this paralleled the decrease in posttransplant renal artery flow. One-year graft and patient survival in the nine infants was 100%. The mean serum creatinine levels at 3, 6, and 12 months were 0.43+/-0.10, 0.48+/-0.15, and 0.49+/-0.16 mg/dl.This study is the first to quantitatively document the blood flow changes occurring after ASK transplantation in infants. There was a greater than two-fold increase in aortic blood flow after ASK transplantation, and this increase was sustained for at least 4 months and appeared to be driven by the blood flow demand of the ASK. However, actual posttransplant renal artery blood flow was significantly less than normal renal artery flow. Our study suggests that aggressive intravascular volume maintenance may be necessary to achieve and maintain optimum aortic blood flow, so as not to further compromise posttransplant renal artery flow and to avoid low-flow states that could induce acute tubular necrosis, vascular thrombosis, or primary nonfunction.

    View details for Web of Science ID 000076585400001

    View details for PubMedID 9798687

  • The International Society for Magnetic Resonance in Medicine. Research directions in MR imaging. Radiology Glover, G. H., Herfkens, R. J. 1998; 207 (2): 289-295

    View details for PubMedID 9577469

  • Breast lesion localization: A freehand, interactive MR imaging-guided technique RADIOLOGY Daniel, B. L., Birdwell, R. L., Ikeda, D. M., Jeffrey, S. S., Black, J. W., Block, W. F., Sawyer-Glover, A. M., Glover, G. H., Herfkens, R. J. 1998; 207 (2): 455-463

    Abstract

    To evaluate interactive magnetic resonance (MR) imaging-guided preoperative needle localization and hookwire placement in the noncompressed breast in patients in the prone position.Nineteen MR imaging-guided breast lesion localization procedures were performed in 17 patients aged 38-70 years (mean age, 48 years) by using an open-platform breast coil in either a 1.5-T, closed-bore imager (n = 14) or a 0.5-T, open-bore imager (n = 5). Rapid imaging (fast spin-echo, water-selective fast spin-echo, or water-specific three-point Dixon gradient-echo) was alternated with freehand manipulation of an MR-compatible needle to achieve accurate needle placement.Up to three manipulations of the needle were required during an average of 9 minutes to reach the target lesion. MR imaging findings confirmed the final needle position within 9 mm of the target in all cases. The accuracy of 10 localizations was independently corroborated either at mammography or at ultrasonography. Nine lesions were visible on MR images only.Interactive MR imaging-guided, freehand needle localization is simple, accurate, and requires no special stereotactic equipment. Lesions throughout the breast, including those in the anterior part of the breast and those near the chest wall, which can be inaccessible with standard grid or compression-plate techniques, can be localized. A variety of needle trajectories in addition to the horizontal path are possible, including circumareolar approaches and tangential needle paths designed to avoid puncture of implants.

    View details for Web of Science ID 000073204300031

    View details for PubMedID 9577495

  • Anterior cruciate ligament injury: Fast spin-echo MR imaging with arthroscopic correlation in 217 examinations AMERICAN JOURNAL OF ROENTGENOLOGY Ha, T. P., Li, K. C., Beaulieu, C. F., Bergman, G., Ch'en, I. Y., Eller, D. J., Cheung, L. P., Herfkens, R. J. 1998; 170 (5): 1215-1219

    Abstract

    Our objective was to evaluate the accuracy of MR imaging strategy that uses primarily fast spin-echo sequences for the diagnosis of anterior cruciate ligament tears.The original clinical interpretations of MR images of 217 examinations of the knee joint were correlated with subsequent arthroscopic results. Each MR examination included a double-echo fast spin-echo sequence as the only imaging sequence in the sagittal plane. Subsequent discordant MR and arthroscopic examinations were then subjected to reanalysis by two observers who were unaware of arthroscopic results to determine if misinterpretations were observer or image dependent. Two hundred sixteen patients who underwent MR imaging for suspected internal derangement of the knee subsequently underwent arthroscopic surgery. Two patients had both knees evaluated. One patient was excluded because he was referred for evaluation for osteomyelitis, not internal derangement. This yielded a total number of 217 MR examinations for suspected internal derangement of the knee.For 56 arthroscopically proven tears, the sensitivity of MR imaging was 96%. The specificity was 98%, yielding an overall accuracy rate of 98%. The positive and negative predictive values were 95% and 99%, respectively. These values are within the ranges of previously reported MR imaging strategies using conventional spin-echo sequences.Fast spin-echo MR imaging of the knee can be an alternative to conventional spin-echo imaging for the detection of anterior cruciate ligament tears.

    View details for Web of Science ID 000073257300014

    View details for PubMedID 9574587

  • Breast cancer: Gadolinium-enhanced MR imaging with a 0.5-T open imager and three-point Dixon technique RADIOLOGY Daniel, B. L., Butts, K., Glover, G. H., Cooper, C., Herfkens, R. J. 1998; 207 (1): 183-190

    Abstract

    To investigate the three-point Dixon technique as a method for obtaining fat-nulled images of contrast material-enhancing breast lesions with a 0.5-T open magnetic resonance (MR) imager.Real and imaginary source images were obtained with an interleaved gradient-echo sequence with a repetition time of 550 msec and echo times of 12.8, 19.8, and 26.8 msec. Twenty-four to 28 sections were obtained in the sagittal plane with a 90 degrees flip angle, 256 x 192 matrix, 3-4.5-mm section thickness, and acquisition time of 10 minutes 54 seconds. A three-point Dixon reconstruction algorithm was used to generate water-specific, fat-specific, and combined images from the raw image data. Twelve breasts in 10 patients and one healthy volunteer were imaged.Three-point Dixon images were superior to extended two-point Dixon and fat-suppressed images and to images generated by means of subtraction of three-dimensional fast spoiled gradient-echo images obtained before contrast material injection from those obtained after.Three-point Dixon imaging provides a robust method for creating fat-nulled images of enhancing breast lesions in the 0.5-T open MR environment. Water-specific three-point Dixon images are successful in regions of B0 heterogeneity and are superior to fat-suppressed images. They are much less susceptible to motion artifact than are subtraction images.

    View details for Web of Science ID 000072662500027

    View details for PubMedID 9530315

  • Ultrafast contrast-enhanced three-dimensional MR angiography: State of the art RADIOGRAPHICS Alley, M. T., Shifrin, R. Y., Pelc, N. J., Herfkens, R. J. 1998; 18 (2): 273-285

    Abstract

    Ultrafast breath-hold contrast material-enhanced magnetic resonance (MR) angiography can be performed with a flexible imaging sequence. With the current generation of high-speed imaging gradients, it is possible to achieve sequence repetition times of 4 msec or less. These repetition times make it possible to obtain high-resolution (512 x 512 x 64) images in under 30 seconds. Applications of this versatile technique include imaging of aortic dissection, thoracic and abdominal aortic aneurysm, pulmonary embolus, carotid stenosis, and peripheral vascular disease. The administration of contrast material must be tailored to the vascular anatomy under examination to avoid venous enhancement. The rapid data acquisition times can be used to image multiple temporal phases or multiple locations. With this technique and administration of a T1-shortening contrast agent, high-quality MR angiography can be routinely performed in a variety of vascular regions (eg, thoracic and abdominal aorta, pulmonary arteries, carotid arteries, lower extremities).

    View details for Web of Science ID 000072493100003

    View details for PubMedID 9536477

  • Three-dimensional shaded-surface rendering of MR images of the breast: technique, applications, and impact on surgical management of breast disease. Radiographics Daniel, B. L., Jeffrey, S. S., Birdwell, R. L., Ikeda, D. M., Sawyer-Glover, A. M., Herfkens, R. J. 1998; 18 (2): 483-496

    Abstract

    Contrast material-enhanced magnetic resonance (MR) imaging is reported to be the most accurate modality for determining the extent of breast cancer before surgery. Three-dimensionally rendered MR images can be used as an adjunct in planning breast surgery. Semiautomated methods are used to isolate the breast tissue within high-resolution MR images and to render the skin with a shaded-surface method. Cut-away views reveal lesions in the interior of the breast. Cut-plane shaded-surface display provides the surgeon with information on the size, extent, and spatial relationships of a breast lesion in a simple, intuitive format. This technique can help the surgeon plan a breast biopsy, lumpectomy, or mastectomy that will maximize local control of breast cancer while minimizing cosmetic damage to the unaffected portions of the breast. In a review of 15 clinical cases, cut-plane shaded-surface rendering aided surgical planning in 10 cases.

    View details for PubMedID 9536491

  • Interactive MR-guided, 14-gauge core-needle biopsy of enhancing lesions in a breast phantom model ACADEMIC RADIOLOGY Daniel, B. L., Birdwell, R. L., Black, J. W., Ikeda, D. M., Glover, G. H., Herfkens, R. J. 1997; 4 (7): 508-512

    Abstract

    The authors attempted to determine the accuracy of magnetic resonance (MR) imaging-guided core-needle biopsy performed with a titanium biopsy needle in a breast phantom.Eight 6-7-mm lesions were created at random positions in a lard breast phantom. Each 0.2-mL lesion contained 0.118 mg of gadopentetate dimeglumine, 0.0025 mL of methylene blue dye, and 23.8 mg of gelatin. Rapid fast spin-echo MR imaging was used to guide placement of a 14-gauge titanium core-biopsy needle. A 1.5-T MR imager was used with an open-platform phased-array breast coil.Visualization of blue dye in core specimens confirmed successful biopsy in 16 of 16 attempts. One (n = 13) or two (n = 3) passes through the "skin" of the phantom were necessary for biopsy. The needle trajectory was adjusted less than three times for each pass through the "skin" in 15 of 16 biopsies. Cores that contained lesion material were obtained in the first sample in 15 of 16 biopsies. On T1-weighted images, needles cast 7-mm-diameter artifacts.MR imaging can be used accurately to guide core-needle biopsy of 6-7-mm lesions in a breast phantom.

    View details for Web of Science ID A1997XG51800009

    View details for PubMedID 9232171

  • Analysis of cardiac function by MRI and stereology JOURNAL OF MICROSCOPY Roberts, N., CRUZORIVE, L. M., Bourne, M., Herfkens, R. J., Karwoski, R. A., Whitehouse, G. H. 1997; 187: 31-42

    Abstract

    Design-based stereology and phase contrast magnetic resonance imaging (MRI) were combined to monitor changes in the volume of the four chambers of the human heart during the cardiac cycle. The data set consisted of 18 adjacent slices (or 'scanning levels') of 0.5 cm thickness, perpendicular to the long axis of the body, and encompassing the whole heart of a healthy volunteer. At each scanning level, a cardiac gated MR image was obtained at each of 16 equally spaced time frames within the cardiac cycle. Given stationarity with respect to time, absence of image artefacts and appropriate definition of chamber boundaries, for each time frame unbiased estimates of total blood volume in the relevant heart chambers were efficiently obtained using the Cavalieri method and point counting. Combined with a proper MRI acquisition, modern stereological methods constitute an efficient and reliable tool to quantify cardiac function noninvasively.

    View details for Web of Science ID A1997XL43500005

    View details for PubMedID 9263438

  • Meniscal tears of the knee: Accuracy of detection with fast spin-echo MR imaging and arthroscopic correlation in 293 patients RADIOLOGY Cheung, L. P., Li, K. C., HOLLETT, M. D., Bergman, A. G., Herfkens, R. J. 1997; 203 (2): 508-512

    Abstract

    To evaluate the accuracy of a magnetic resonance (MR) imaging strategy that uses primarily fast spin-echo (SE) sequences for the diagnosis of meniscal tears.The original clinical interpretations of MR images in 293 patients who underwent imaging for suspected internal derangement of a knee joint were correlated with results from subsequent arthroscopy. MR examination included a double-echo fast SE sequence as the only imaging in the sagittal plane.The sensitivity and specificity for 143 confirmed tears of the medial meniscus were 89% and 84%, respectively, while the values for 96 confirmed tears of the lateral meniscus were 72% and 93%. These values are within the ranges of values recently reported for imaging strategies relying predominantly on conventional SE sequences.Fast SE imaging of the knee can be an alternative to conventional SE imaging for the detection of meniscal tears.

    View details for Web of Science ID A1997WU53200042

    View details for PubMedID 9114113

  • GADOTERIDOL-ENHANCED MR-IMAGING OF MALIGNANT HEPATIC-TUMORS - EFFECTS OF TRIPLE VERSUS STANDARD DOSES ON LESION-LIVER CONTRAST AMERICAN JOURNAL OF ROENTGENOLOGY Petersein, J., Saini, S., Mitchell, D. G., Davis, P. L., Johnson, C. D., Kuhlman, J. E., Parisky, Y. R., Runge, V. M., Weinreb, J., Bernardino, M. E., Delange, E. E., Gorczyca, D., Herfkens, R. J., Schnall, M. 1995; 165 (5): 1157-1161

    Abstract

    The purpose of this study was to compare liver signal-to-noise ratio (SNR), lesion SNR, and lesion-liver contrast-to-noise-ratio (CNR) in patients with malignant liver lesions after the administration of a standard dose (0.1 mmol/kg of body weight) or a triple dose (0.3 mmol/kg) of a gadolinium chelate (gadoteridol). We hypothesized that the higher dose would produce a higher lesion-liver CNR and therefore increase the conspicuity of hepatic lesions.A total of 85 patients with malignant hepatic masses (61 metastases, 22 hepatocellular carcinomas, and two lymphomas) proved by histologic or follow-up studies underwent MR imaging at 1.5 T. T1-weighted spin-echo imaging and gradient-echo imaging were done before and within 1 min after (gradient echo) as well as 5 (spin echo) and 15 (spin echo) min after the injection of 0.1 or 0.3 mmol of gadoteridol per kg, randomized before the start of the study (39 patients received the standard dose, and 46 received the triple dose). The signal intensities of the liver and lesions and the SD of background noise were measured by use of regions of interest to calculate the SNR of the liver and malignant lesions and the lesion-liver CNR.The lesion-liver CNR was increased significantly at 5 and 15 min after the administration of gadoteridol. No significant differences in the liver SNR, lesion SNR, and lesion-liver CNR (after 1 min: standard dose, -5 +/- 8, and triple dose, -4 +/- 14; after 5 min: standard dose, -1 +/- 5, and triple dose, 2 +/- 8; and after 15 min: standard dose, 1 +/- 5, and triple dose, 6 +/- 20) were found between the doses at all time points.Triple-dose gadoteridol does not improve the lesion-liver contrast of malignant hepatic lesions over that provided by the standard dose and is not warranted for liver MR imaging.

    View details for Web of Science ID A1995TA73300027

    View details for PubMedID 7572495

  • 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

  • CINE SPIRAL IMAGING MAGNETIC RESONANCE IN MEDICINE Liao, J. R., Sommer, F. G., Herfkens, R. J., Pelc, N. J. 1995; 34 (3): 490-493

    Abstract

    Interleaved spiral scanning of k-space is an efficient and fast method for imaging dynamic processes. In this article, a cine version of interleaved spiral imaging is presented. The method is shown to overcome the "lightning-flash" artifacts of the conventional triggered (gated) method. Compared with the segmented k-space 2DFT method, it achieves better temporal resolution in a comparable or shorter scan time. Preliminary human studies show that the method is a promising tool for imaging dynamic processes.

    View details for Web of Science ID A1995RR68700029

    View details for PubMedID 7500891

  • TRACKING OF CYCLIC MOTION WITH PHASE-CONTRAST CINE MR VELOCITY DATA JMRI-JOURNAL OF MAGNETIC RESONANCE IMAGING Pelc, N. J., Drangova, M., Pelc, L. R., Zhu, Y., Noll, D. C., BOWMAN, B. S., Herfkens, R. J. 1995; 5 (3): 339-345

    Abstract

    A method of computing trajectories of objects by using velocity data, particularly as acquired with phase-contrast magnetic resonance (MR) imaging, is presented. Starting from a specified location at one time point, the method recursively estimates the trajectory. The effects of measurement noise and eddy current-induced velocity offsets are analyzed. When the motion is periodic, trajectories can be computed by integrating in both the forward and backward temporal directions, and a linear combination of these trajectories minimizes the effect of velocity offsets and maximizes the precision of the combined trajectory. For representative acquisition parameters and signal-to-noise ratios, the limitations due to measurement noise are acceptable. In a phantom with reciprocal rotation, the measured and true trajectories agreed to within 3.3%. Sample trajectory estimates of human myocardial regions are encouraging.

    View details for Web of Science ID A1995QZ28100015

    View details for PubMedID 7633112

  • SIMULTANEOUS TEMPORAL RESOLUTION OF CARDIAC AND RESPIRATORY MOTION IN MR-IMAGING RADIOLOGY Fredrickson, J. O., WEGMULLER, H., Herfkens, R. J., Pelc, N. J. 1995; 195 (1): 169-175

    Abstract

    To evaluate a magnetic resonance (MR) imaging method that allows for simultaneous resolution of both the cardiac and respiratory cycles.Conventional and phase-contrast cine sequences were modified to provide additional resolution of the respiratory cycle. Data were collected in 11 healthy volunteers during MR imaging of the heart and portal vein. The imaging time was increased over that of a conventional cine acquisition by a factor equal to the number of frames in the respiratory cycle. Data were compared with those from comparable sequences in which only one motion cycle was resolved.In the heart, motion due to cardiac dynamics was separated from respiration-induced excursions. The extent of motion could be measured, and artifacts were minimized. Changes in flow rate as a function of both motion cycles were resolved and quantified in both the portal vein and superior vena cava.This method allows for simultaneous resolution of cardiac and respiratory motion cycles and helps provide a more physiologic view of the effects of cardiac and respiratory variations.

    View details for Web of Science ID A1995QM66300033

    View details for PubMedID 7892461

  • PHASE-CONTRAST MRI ASSESSMENT OF PEDAL BLOOD-FLOW EUROPEAN RADIOLOGY Debatin, J. F., Dalman, R., Herfkens, R. J., Harris, E. J., Pelc, N. J. 1995; 5 (1): 36-42
  • EVALUATION OF MYOCARDIAL MOTION TRACKING WITH CINE-PHASE CONTRAST MAGNETIC-RESONANCE-IMAGING INVESTIGATIVE RADIOLOGY Pelc, L. R., Sayre, J., Yun, K., Castro, L. J., Herfkens, R. J., Miller, D. C., Pelc, N. J. 1994; 29 (12): 1038-1042

    Abstract

    The accuracy of myocardial motion measurements, computed from cine-phase contrast (cine-PC) magnetic resonance (MR) velocity data, was compared with directly visualized motion of MR signal voids caused by implanted tantalum markers in anesthetized dogs.Magnetic resonance imaging (MRI) data were electrocardiogram-gated and divided into 16 phases per cardiac cycle. Myocardial trajectories as a function of time in the cardiac cycle were measured using both methods for four to seven markers in each of eight animals.The peak observed in-plane excursion was 4.0 +/- 2.1 mm. The average deviation between displacements derived from velocity data versus displacements visualized directly was 1.1 +/- 0.7 mm (27.5% of the peak displacement). The difference was less if three separate MR scans were used to measure each velocity component in the cine-PC method. This improvement is probably caused by improved temporal resolution.Cine-PC MRI offers a noninvasive method for accurate quantification of myocardial motion.

    View details for Web of Science ID A1994QG42000005

    View details for PubMedID 7721545

  • MAGNETIC-RESONANCE-IMAGING EVALUATION OF PULMONARY VASCULAR MALFORMATIONS CHEST Silverman, J. M., JULIEN, P. J., Herfkens, R. J., Pelc, N. J. 1994; 106 (5): 1333-1338

    Abstract

    The purpose of our study was to establish magnetic resonance imaging (MRI) criteria for the diagnosis of pulmonary vascular malformations (PVMs).Since 1987, 11 patients have been referred for chest MRI at our institution because of findings suggestive of a PVM. They were evaluated with a 1.5-T MRI system, incorporating a combination of spin-echo, gradient-recalled echo (GRE) cine, and 2-D phase contrast (PC) cine sequences. We used the following MRI criteria to diagnose PVM: (1) flow void or intermediate gray signal on spine-echo sequences; (2) bright signal on GRE cine sequences; and (3) bright signal consistent with flow detected on PC cine sequences using relatively low velocity ranges. Twelve patients not suspected of having a PVM served as controls; all had both MRI and pulmonary angiography to evaluate for central pulmonary embolus.Eight patients in the study group had PVM as determined with MRI using these criteria. In four of these patients, a PVM was confirmed by subsequent pulmonary angiography. Three patients did not have PVM utilizing these criteria; two had neoplasms and one had presumed mucus plugging and/or atelectasis that resolved spontaneously. The smallest vascular malformation detected by MRI was 1 cm. None of the control patients had PVM by MRI or pulmonary angiography.Utilizing these criteria, we believe that MRI is potentially an excellent noninvasive modality to evaluate PVM, and we stress that some form of PC cine sequence must be performed to determine if indeed there is blood flow within a suspicious lesion.

    View details for Web of Science ID A1994PR29300009

    View details for PubMedID 7956380

  • Magnetic resonance imaging in adult congenital heart disease. Journal of thoracic imaging Wexler, L., Higgins, C. B., Herfkens, R. J. 1994; 9 (4): 219-229

    Abstract

    Some patients with congenital cardiac anomalies develop their first symptoms as adults, and many more will survive to adulthood with congenital lesions that have been treated surgically. Magnetic resonance imaging (MRI) currently provides sufficient morphological information to allow the anatomical diagnosis of congenital abnormalities involving the heart and the great arteries. Newer MR techniques have also been developed that provide functional information such as measurements of valve gradients, stroke volumes, regurgitant volumes, and shunt volumes. Cardiac evaluation utilizing MR techniques may soon replace cardiac catheterization for the preoperative diagnosis of congenital heart disease and its long-term follow-up.

    View details for PubMedID 7830293

  • HEPATIC METASTASES AND CAVERNOUS HEMANGIOMAS - DISTINCTION WITH STANDARD-DOSE AND TRIPLE-DOSE GADOTERIDOL-ENHANCED MR-IMAGING RADIOLOGY Mitchell, D. G., Saini, S., Weinreb, J., Delange, E. E., Runge, V. M., Kuhlman, J. E., Parisky, Y., Johnson, C. D., Brown, J. J., Schnall, M., Herfkens, R. J., Davis, P. L., Gorczyca, D., Sica, G., Foster, G. S., Bernardino, M. E. 1994; 193 (1): 49-57
  • QUANTITATIVE MAGNETIC-RESONANCE FLOW IMAGING MAGNETIC RESONANCE QUARTERLY Pelc, N. J., Sommer, F. G., Li, K. C., Brosnan, T. J., Herfkens, R. J., Enzmann, D. R. 1994; 10 (3): 125-147

    Abstract

    Time-of-flight and phase shift methods have both been used for vascular imaging with magnetic resonance. Phase methods, and phase contrast in particular, are well suited to quantitative measurements of velocity and volume flow rate. The most robust methods for measuring flow encode through-plane velocity into phase shift and compute flow by integrating the measured velocity over the vessel lumen. The accuracy of the flow data can be degraded by the effects of acceleration and eddy currents and by partial volume effects, including the effects of finite slice thickness and resolution, pulsatile waveforms, motion, and chemical shift. The reproducibility depends on the signal-to-noise of the data and the strength of the flow encoding and can be degraded by inconsistent definition of the vessel boundary. The adjustable flow sensitivity inherent in this method is a particular asset, allowing phase contrast flow measurement to operate over a dynamic range exceeding 10(5). Recently developed rapid imaging methods are helpful in applications that would be compromised by respiratory motion. With care, excellent quantitative data can be quickly obtained in vivo, and the resulting flow information is valuable for the diagnosis and management of a variety of conditions.

    View details for Web of Science ID A1994PM96800001

    View details for PubMedID 7811608

  • SINGLE BREATH-HOLD PULMONARY MAGNETIC-RESONANCE ANGIOGRAPHY - OPTIMIZATION AND COMPARISON OF 3 IMAGING STRATEGIES INVESTIGATIVE RADIOLOGY Rubin, G. D., Herfkens, R. J., Pelc, N. J., Foo, T. K., Napel, S., Shimakawa, A., Steiner, R. M., Bergin, C. J. 1994; 29 (8): 766-772

    Abstract

    Ultrafast gradient-recalled-echo techniques for obtaining high-quality pulmonary magnetic resonance angiograms within a single breath-hold were optimized.Fourteen subjects were imaged with both the body coil and a phased-array surface coil, using three gradient-recalled-echo pulse sequences: 1) two-dimensional sequential; 2) two-dimensional interleaved; and 3) volumetric acquisitions. Image quality was assessed with varied flip angle, receiver bandwidth, slice thickness/number, and matrix size. Cardiac compensation diminished ghost artifacts in the interleaved sequence. Individual sagittal sections and maximum intensity projections were reviewed.Pulmonary magnetic resonance angiograms acquired with volumetric and two-dimensional interleaved gradient-recalled-echo pulse sequences benefit greatest from intravenous gadolinium and result in greater pulmonary arterial visualization than traditional time-of-flight techniques. Phased-array coils result in improved vessel detection.High-quality breath-held pulmonary magnetic resonance angiography can be obtained with an intravenous contrast-enhanced gradient-recalled-echo acquisition; however, image quality is dependent on the pulse sequence.

    View details for Web of Science ID A1994PE81100006

    View details for PubMedID 7960627

  • MAGNETIC-RESONANCE-IMAGING AND MEASUREMENT OF BLOOD-FLOW WESTERN JOURNAL OF MEDICINE McDonnell, C. H., Herfkens, R. J., Norbash, A. M., Rubin, G. D. 1994; 160 (3): 237-242

    Abstract

    Blood flow can be shown as a negative image with magnetic resonance spin-echo techniques or as a positive image with gradient-echo techniques. Phase contrast refers to techniques where structures can be seen because of flow-induced phase shifts. These techniques can show the presence (slow flow) and also the direction of flow. Gradient-echo techniques--including phase-contrast versions--can be used with cardiac synchronization to obtain multiple images during the cardiac cycle. These images can be viewed in a movie or cine format to provide dynamic information about blood flow. Blood flow can be measured by using contrast media in boluses or even more elegantly with phase-contrast methods. Clinical applications of flow measurements are growing rapidly. Phase-contrast or gradient-echo techniques can be used to create magnetic resonance angiography, which was first used to study the carotid bifurcation and intracranial circulation and is now being used throughout the body.

    View details for Web of Science ID A1994NB98200004

    View details for PubMedID 8191756

  • RENAL-ARTERY BLOOD-FLOW - QUANTITATION WITH PHASE-CONTRAST MR-IMAGING WITH AND WITHOUT BREATH-HOLDING RADIOLOGY Debatin, J. F., Ting, R. H., WEGMULLER, H., Sommer, F. G., Fredrickson, J. O., Brosnan, T. J., BOWMAN, B. S., Myers, B. D., Herfkens, R. J., Pelc, N. J. 1994; 190 (2): 371-378

    Abstract

    To compare the accuracy of 16-frame cine phase-contrast (PC) magnetic resonance (MR) imaging with those of two breath-hold PC techniques in the measurement of renal artery blood flow.In vitro flow measurements were performed in a segment of harvested human artery embedded in gel. For the cine PC acquisition, respiratory motion was simulated. In eight subjects with recently obtained para-amino-hippurate-clearance renal blood flow data, renal artery flow measurements were subsequently performed with two breath-hold imaging techniques and with cine PC imaging during shallow respiration.Breath-hold sequences were significantly more accurate than conventional cine PC sequences both in vitro (P < .005) and in vivo (P < .05). Cine PC imaging tended to overestimate flow (in vivo mean, 24.47% +/- 9.94), reflecting artifactual enlargement of the apparent vessel size.Reliable blood flow measurements in the renal artery are possible with breath-hold PC MR imaging.

    View details for Web of Science ID A1994MW44400017

    View details for PubMedID 8284383

  • DETERMINING THE VOLUME OF PROSTATIC-CARCINOMA - VALUE OF MR-IMAGING WITH AN EXTERNAL-ARRAY COIL AMERICAN JOURNAL OF ROENTGENOLOGY Sommer, F. G., Nghiem, H. V., Herfkens, R., McNeal, J., Low, R. N. 1993; 161 (1): 81-86

    Abstract

    The size of prostatic carcinomas, as determined by estimations of the tumor volume, has a direct correlation with the histologic grade and stage. Therefore, accurate information about tumor volume can play an important role in determining appropriate treatment and establishing a patient's prognosis. Accordingly, we performed a study to assess the accuracy of MR imaging with external-array coils and the fast spin-echo technique for determining tumor volume in patients with prostatic cancer.In a prospective study, 20 patients with biopsy-proved prostatic cancer had MR imaging before radical prostatectomy. A 1.5-T system, a prototype external-array coil, and fast spin-echo technique were used to obtain axial T2-weighted (4000/120 [TR/TE]) MR images throughout the prostate and seminal vesicles. Contiguous 5-mm sections were obtained with a 256 x 256 or 256 x 192 matrix, 24-cm field of view, four excitations, and fat suppression. The volumes of cancer obtained with MR imaging and surgical specimens were determined independently. The areas of tumor were determined from individual axial sections by summing and multiplying by the section thickness.Seventeen of the 20 cancers were detected on MR images. A significant correlation between the volume of the tumor as determined with MR imaging and measurements of the specimens was observed (r = .81, p < .001). Four transition zone tumors were detected as zones of rather homogeneous decreased intensity. One important source of error for volumes determined with MR images was a limitation in the histologic specificity of MR imaging for the delineation of cancer; in some cases benign changes or normal prostates were interpreted as cancer. Another limitation was the presence of changes after biopsy that concealed portions of 10 of the 17 tumors visualized.The accuracy of the MR technique used was not sufficient for reliable prediction of tumor volume. The lack of specificity of T2-weighted MR imaging for cancer detection and the presence of changes caused by biopsy were major sources of error.

    View details for Web of Science ID A1993LW01500018

    View details for PubMedID 8517328

  • FAST MULTIPLANAR SPOILED GRADIENT-RECALLED IMAGING OF THE LIVER - PULSE SEQUENCE OPTIMIZATION AND COMPARISON WITH SPIN-ECHO MR IMAGING AMERICAN JOURNAL OF ROENTGENOLOGY Low, R. N., Francis, I. R., Herfkens, R. J., Jeffrey, R. B., Glazer, G. M., Foo, T. K., Shimakawa, A., Pelc, N. J. 1993; 160 (3): 501-509

    Abstract

    The purpose of this study was to optimize a new rapid-acquisition MR pulse sequence, called fast multiplanar spoiled gradient-recalled (FMPSPGR) imaging, for breath-hold imaging of the liver and to compare unenhanced and contrast-enhanced FMPSPGR with standard spin-echo imaging in detecting liver tumors.The pulse sequence was optimized at 1.5 T with a healthy volunteer. Various scanning parameters were evaluated, and liver-spleen signal difference/noise measurements were used to estimate lesion contrast-to-noise ratios. We examined 24 patients with hepatic masses using the optimized sequence with spin-echo T1-weighted and T2-weighted imaging as well as unenhanced and gadopentetate dimeglumine-enhanced FMPSPGR imaging. The contrast-to-noise ratio for the hepatic tumors was determined for each sequence. Three radiologists who did not know the biopsy or test results reviewed all images for lesion conspicuity, lesion tissue specificity, and overall image quality.A comparison of unenhanced FMPSPGR images with spin-echo T1-weighted images showed a 40% improvement in mean contrast-to-noise ratio and a 70% improvement in liver signal-to-noise ratio for the FMPSPGR images. A comparison of gadopentetate dimeglumine-enhanced FMPSPGR images with spin-echo T1- and T2-weighted images showed a superior contrast-to-noise ratio for the enhanced FMPSPGR images in 17 (68%) of 25 hepatic lesions, which included all hepatic cysts (n = 3) and all hepatomas (n = 6), and in six of 12 patients with other liver tumors. The results of contrast-to-noise ratio for four patients with hemangiomas were mixed. For the remaining eight lesions, the contrast-to-noise ratio for spin-echo T1- and T2-weighted images predominated in three and five cases, respectively. Contrast-enhanced FMPSPGR images revealed a 40% and 300% increase in contrast-to-noise ratio compared with T2- and T1-weighted images, respectively. All three radiologists preferred the contrast-enhanced FMPSPGR images for overall image quality. For lesion conspicuity and specificity, however, the three radiologists differed, with a preference for the FMPSPGR images in 52%, 80%, and 40% of cases for lesion conspicuity and in 68%, 40%, and 60% of cases for lesion specificity.FMPSPGR is a new, ultrafast MR sequence that provides T1-weighted images of the liver during suspended respiration. Contrast-to-noise ratio and liver signal-to-noise ratio are significantly improved over those on conventional spin-echo T1-weighted images. The combination of breath-hold FMPSPGR with gadopentetate dimeglumine is an excellent technique that can be used to rapidly evaluate the liver with superior overall image quality. Contrast-to-noise ratios are generally superior to T2-weighted spin-echo images, making this technique a useful adjunct to conventional spin-echo MR imaging.

    View details for Web of Science ID A1993KM93500009

    View details for PubMedID 8381572

  • 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

  • GADOLINIUM-ENHANCED MRI OF THE ABNORMAL PROSTATE MAGNETIC RESONANCE IMAGING Sommer, F. G., Nghiem, H. V., Herfkens, R., McNeal, J. 1993; 11 (7): 941-948

    Abstract

    A prospective study of the use of a low osmolar gadolinium-based intravenous contrast material for MRI of the abnormal prostate was performed. Eight patients scheduled for prostatectomy, six with prostate cancer and two with benign prostatic hyperplasia (BPH), were imaged preoperatively on a 1.5 T system using a pelvic coil array and employing Gadodiamide (0.3 mmol/kg). T2-weighted fast-spin echo (FSE) imaging was also performed in the same axial planes employed for gadolinium-enhanced studies. Detailed pathologic correlation was performed for the six patients with carcinoma. While regions of BPH and cancer enhanced to a similar degree following intravenous contrast agent, BPH enhancement was more heterogeneous than cancer. No advantages in detecting prostate cancer, in differentiating cancer from BPH or normal prostatic tissue, or in assessing extra-prostatic spread of cancer were observed for the contrast-enhanced studies compared to T2-weighted FSE imaging.

    View details for Web of Science ID A1993MB03400005

    View details for PubMedID 7694028

  • ARTERIAL AND VENOUS-BLOOD FLOW - NONINVASIVE QUANTITATION WITH MR IMAGING RADIOLOGY Pelc, L. R., Pelc, N. J., Rayhill, S. C., Castro, L. J., Glover, G. H., Herfkens, R. J., Miller, D. C., Jeffrey, R. B. 1992; 185 (3): 809-812

    Abstract

    Quantitative measurements of arterial and venous blood flow were obtained with phase-contrast cine magnetic resonance (MR) imaging and compared with such measurements obtained by means of implanted ultrasound (US) blood flow probes in anesthetized dogs. The US flowmeter was enabled during a portion of each MR imaging sequence to allow virtually simultaneous data acquisition with the two techniques. MR imaging data were gated by means of electrocardiography and divided into 16 phases per cardiac cycle. The rates of portal venous blood flow measured with MR imaging and averaged across the cardiac cycle (710 mL/min +/- 230 [standard deviation]) correlated well with those measured with the flowmeter and averaged in like fashion (751 mL/min +/- 238) (r = .995, slope = 1.053). The correspondence in arterial blood flow was almost as good. No statistically significant difference existed between the paired measurements of blood flow obtained with MR imaging and the implanted probe. It is concluded that, as a noninvasive means of accurate quantification of blood flow, phase-contrast MR imaging may be especially useful in deep blood vessels in humans.

    View details for Web of Science ID A1992JZ34700042

    View details for PubMedID 1438767

  • THE PELVIS - T2-WEIGHTED FAST SPIN-ECHO MR-IMAGING RADIOLOGY Nghiem, H. V., Herfkens, R. J., Francis, I. R., Sommer, F. G., Jeffrey, R. B., Li, K. C., Steiner, R. M., Glover, G. H. 1992; 185 (1): 213-217

    Abstract

    Fast spin-echo (SE) T2-weighted magnetic resonance (MR) imaging provides images with highly T2-weighted contrast in substantially reduced imaging times. In a prospective evaluation, fast SE T2-weighted imaging of the pelvis was compared with conventional SE T2-weighted imaging in 30 consecutive patients in whom pelvic pathologic conditions were suspected. Three reviewers independently analyzed the images for (a) overall image quality, (b) pelvic organ definition, (c) conspicuity of pelvic fluid, and (d) conspicuity of pelvic pathologic conditions. Fast SE images were rated superior to conventional SE T2-weighted images in 60% (54 of 90) of the case reviews for overall image quality, in 69% (62 of 90) for pelvic organ definition, in 63% (57 of 90) for conspicuity of pelvic fluid, and in 68% (43 of 63) for conspicuity of pelvic pathologic conditions. The fast SE examinations were typically three to four times faster than conventional SE T2-weighted examinations. No pathologic findings seen on conventional SE T2-weighted images were undetected on fast SE images. Fast SE images may replace conventional SE T2-weighted images in MR imaging of the pelvis.

    View details for Web of Science ID A1992JN60800039

    View details for PubMedID 1523311

  • A METHOD FOR THE PREPARATION OF METHEMOGLOBIN-CONTAINING HUMAN RED-CELL SUSPENSIONS CLINICAL AND LABORATORY HAEMATOLOGY KOEPKE, J. R., Koepke, J. A., Boyko, O., Herfkens, R. J. 1992; 14 (1): 69-72

    Abstract

    The variables affecting the formation and stability of intracellular methaemoglobin were examined. A method is proposed for the preparation of intracellular methaemoglobin specimens.

    View details for Web of Science ID A1992HP52900009

    View details for PubMedID 1600695

  • Phase contrast cine magnetic resonance imaging. Magnetic resonance quarterly Pelc, N. J., Herfkens, R. J., Shimakawa, A., Enzmann, D. R. 1991; 7 (4): 229-254

    Abstract

    Phase contrast cine magnetic resonance imaging (MRI) combines the flow-dependent contrast of phase contrast MRI with the ability of cardiac cine imaging to produce images throughout the cardiac cycle. Two pulse sequence types are used for sensitivity to flow in one direction, whereas four are needed for sensitivity in all directions. Several alternatives for synchronization of the data to the cardiac cycle exist. Retrospectively interpolated methods can image the entire cardiac cycle efficiently. Rapid interleaving of the various sequence types ensures immunity to motion misregistration. The technique produces images in which contrast is related to flow velocity as well as magnitude images such as those of conventional cine MRI. The data can be interpreted qualitatively to demonstrate the presence, magnitude, and direction of flow, and quantitatively to provide estimates of flow velocity, volume flow rate, and displaced volumes. Phase contrast cine MRI is helpful in the diagnosis of aortic dissections, in the study of flow distributions in large vessels such as pulmonary arteries, as well as in smaller vessels such as carotid and basilar arteries, and in the evaluation of complex anatomical variants. Future developments are expected to reduce imaging time and expand the quantitative applications.

    View details for PubMedID 1790111

  • EVALUATION OF ACUTE-RENAL-FAILURE WITH MAGNETIC-RESONANCE-IMAGING USING GRADIENT-ECHO AND GD-DTPA INVESTIGATIVE RADIOLOGY Munechika, H., SULLIVAN, D. C., Hedlund, L. W., Beam, C. A., Sostman, H. D., Herfkens, R. J., Pelc, N. J. 1991; 26 (1): 22-27

    Abstract

    Detection of acute renal failure (ARF) using fast-scan magnetic resonance imaging (MRI) with Gd-DTPA was studied in a dog model. ARF was produced in five dogs by infusion of norepinephrine (0.75 micrograms/kg/min) into the renal arteries for 40 minutes. MRI was performed 1 hour later and compared with baseline (pre-ARF) MRI. There was no significant difference in the ratios of signal intensity-vs.-time curves from 0 to 35 seconds after injection of Gd-DTPA. However, a difference between the outer and inner medulla was significant in the time period of 5 to 20 minutes after Gd-DTPA injection. These later signal intensity differences by fast-scan (gradient-echo) technique may be useful in the evaluation of ARF.

    View details for Web of Science ID A1991ER52500005

    View details for PubMedID 2022449

  • INTERVERTEBRAL-DISK - NORMAL AGE-RELATED-CHANGES IN MR SIGNAL INTENSITY RADIOLOGY Modic, M. T., Herfkens, R. J. 1990; 177 (2): 332-333

    View details for Web of Science ID A1990EE79900006

    View details for PubMedID 2217764

  • NMR assessment of valvular disease. La Radiologia medica Herfkens, R. J. 1990; 80 (1-2): 111-117

    View details for PubMedID 2217928

  • DETECTION, CHARACTERIZATION AND FUNCTIONAL ASSESSMENT OF REPERFUSED Q-WAVE ACUTE MYOCARDIAL-INFARCTION BY CINE MAGNETIC-RESONANCE-IMAGING AMERICAN JOURNAL OF CARDIOLOGY Meese, R. B., Spritzer, C. E., NEGROVILAR, R., Bashore, T., Herfkens, R. J. 1990; 66 (1): 1-9

    Abstract

    The capability of dynamic gradient-refocused magnetic resonance imaging (cine MRI) to detect, localize and functionally assess acute myocardial infarction (AMI) in 25 patients at a mean time interval of 7 days after AMI was evaluated. Fifteen asymptomatic volunteers were also examined to determine the specificity of the observations. Upon presentation, each patient received intravenous thrombolytic therapy, underwent immediate cardiac catheterization and had percutaneous transluminal coronary angioplasty performed when coronary reperfusion was absent. Twenty-four of the patients had documented coronary reperfusion at a mean interval of 259 +/- 129 minutes. Global ejection fraction and regional wall motion abnormalities were evaluated at 7 days by cine MRI, left ventriculography and radionuclide angiography. Twenty patients with both an absolute decrease in myocardial signal and a matched regional wall motion abnormality had AMI properly identified by cine MRI. In contrast, the finding of both decreased signal intensity and a matched regional wall motion abnormality was absent in the group of asymptomatic volunteers. The ejection fraction by cine MRI correlated better with the ejection fraction by left ventriculography (r = 0.94, standard error of the estimate = 3.6) than did the ejection fraction by radionuclide angiography (r = 0.82, standard error of the estimate = 5.8). The regional wall motion concordance rate in comparison to left ventriculography was similar for both cine MRI (69%) and radionuclide angiography (65%). These findings suggest that cine MRI may play an important role in the future detection and functional characterization of AMI.

    View details for Web of Science ID A1990DL65800001

    View details for PubMedID 2360522

  • HEPATIC HEMANGIOMAS VS METASTASES - MR DIFFERENTIATION AT 1.5-T AMERICAN JOURNAL OF ROENTGENOLOGY LOMBARDO, D. M., Baker, M. E., Spritzer, C. E., Blinder, R., Meyers, W., Herfkens, R. J. 1990; 155 (1): 55-59

    Abstract

    We retrospectively studied the value of MR imaging at 1.5 T in distinguishing hepatic hemangiomas (n = 15) from metastases (n = 15) by using (1) lesion/liver signal-intensity ratios, (2) contrast/noise ratios, and (3) T2 relaxation time on long TR/TE spin-echo (SE) sequences. Lesion/liver margin sharpness, lesion shape, and overall lesion morphologic pattern were evaluated also. Univariate logistic regression analysis of the quantitative data showed that T2 was the only statistically significant (p less than .02) variable for distinguishing a hemangioma from a metastasis. A receiver-operator-characteristic plot of T2 produced an area of 0.80 (+/- 0.08). T2 values for these lesions still overlapped with those for metastases. Morphologically, hemangiomas were sharply marginated (80%), rounded or oval (93%), homogeneous, hyperintense lesions (73%), whereas metastases were poorly marginated (66%) and inhomogenous (67%) lesions. The marked, hyperintense appearance was present in 27% of metastases. Retrospective, multivariate logistic regression analysis of T2 and the presence of hyperintense morphology did not improve results based on T2 alone. Morphologic criteria are helpful in differentiation, as some metastases have a prolonged T2 and are not homogenous, hyperintense lesions. In cases where T2 or morphology are equivocal, other diagnostic tests may help confirm the MR findings. We currently use a T2 of greater than 88 msec and the presence of hyperintense morphology to diagnose hemangiomas. Despite both quantitative and qualitative analysis, data for these hemangiomas and metastases still overlap.

    View details for Web of Science ID A1990DK48700010

    View details for PubMedID 2112864

  • BRAIN T1 MEASURED BY MAGNETIC-RESONANCE-IMAGING IN BULIMIA BIOLOGICAL PSYCHIATRY HOFFMAN, G. W., Ellinwood, E. H., ROCKWELL, W. J., Herfkens, R. J., NISHITA, J. K., GUTHRIE, L. F. 1990; 27 (1): 116-119

    View details for Web of Science ID A1990CH93200016

    View details for PubMedID 2297548

  • MR-TUTOR - A PROGRAM FOR TEACHING THE INTERDEPENDENCE OF FACTORS WHICH INFLUENCE SIGNAL INTENSITY IN MAGNETIC-RESONANCE IMAGING COMPUTERIZED MEDICAL IMAGING AND GRAPHICS POSTERARO, R. H., Blinder, R. A., Herfkens, R. J. 1989; 13 (5): 393-406

    Abstract

    Magnetic resonance (MR) imaging is a valuable diagnostic radiologic procedure. The appearance of tissues on the MR scan is dependent upon a complex relationship among a number of variables. We have written a computer program which teaches students of magnetic resonance imaging the interdependence of these variables and how they affect the appearance of tissues on MR images. The program is written in BASIC for the IBM* and compatible computers. A listing of the program appears in the Appendix of this article.

    View details for Web of Science ID A1989AR37600003

    View details for PubMedID 2680054

  • HETEROGENEOUS SIGNAL INTENSITY IN MAGNETIC-RESONANCE IMAGES OF HYPERTROPHIED LEFT-VENTRICULAR MYOCARDIUM MAGNETIC RESONANCE IMAGING Zahler, R., Chelmow, D., Gore, J., Wilkens, K., Pope, C., Sostman, H. D., MEESE, R., NEGROVILAR, R., Herfkens, R. J., Wackers, F. J., Zaret, B. L. 1989; 7 (5): 517-528

    Abstract

    Left ventricular hypertrophy is associated with decreased longevity and often leads to congestive heart failure. An exploratory study of magnetic resonance imaging in human left ventricular hypertrophy was performed. First, 13 patients with left ventricular hypertrophy and 7 controls of similar ages were studied using electrocardiogramgated end-diastolic images. Visual inspection suggested that low-intensity zones were frequently found within the hypertrophied myocardium. To verify this observation, the images were processed with semi-automatic edge detection and a derivative-based tissue characterization algorithm, yielding tissue heterogeneity indices (THI-A and THI-V) which objectively measured the low-intensity zones. THI-A and THI-V were both significantly greater in left ventricular hypertrophy patients than in controls (THI-A: 0.111 vs 0.038, p = 0.009). THI was also significantly correlated with duration of disease and electrocardiographic abnormalities. To validate these initial findings prospectively, the same quantitative analysis was applied to magnetic resonance images of an additional 20 left ventricular hypertrophy patients and 12 controls from two institutions, using different imaging systems and different acquisition parameters. Again, THI was significantly greater in patients than in controls. Analysis of end-systolic images yielded similar results. In four dogs with left ventricular hypertrophy induced by aortic banding, THI showed a statistically significant increase as left ventricular hypertrophy developed. Hypertrophied myocardium thus shows reproducible differences from normal tissue with magnetic resonance imaging; hence, quantitative magnetic resonance tissue characterization may be useful in assessing pathologic changes in LVH.

    View details for Web of Science ID A1989AT87000008

    View details for PubMedID 2532699

  • MR EVALUATION OF ADRENAL MASSES AT 1.5-T AMERICAN JOURNAL OF ROENTGENOLOGY Baker, M. E., Blinder, R., SPRITZER, C., Leight, G. S., Herfkens, R. J., Dunnick, N. R. 1989; 153 (2): 307-312

    Abstract

    We retrospectively studied the value of MR imaging at 1.5 T to distinguish between nonadenomatous (n = 17) and adenomatous (n = 15) adrenal masses on the basis of (1) signal-intensity ratios on T1- and T2-weighted spin-echo images, (2) T2 relaxation times, and (3) T2 relaxation-time ratios. Univariate and then multivariate logistic regression were applied to these quantitative parameters to determine which of these best discriminated nonadenomas from adenomas, and whether or not more than one of these parameters improved the prediction. The adrenal mass/liver signal-intensity ratio on T2-weighted spin-echo images could not be used to differentiate nonadenomas from adenomas. Adrenal mass/fat signal-intensity ratios on T2-weighted spin-echo images, adrenal/liver T2 relaxation-time ratios, and adrenal mass T2 relaxation times were best for distinguishing nonadenomas from adenomas. By using a T2 value of greater than 61 msec, the true-positive ratio/false-positive ratio of differentiating nonadenomas from adenomas was 100%/20%; at greater than 82 msec, it was 64%/0.06%. The adrenal mass/fat signal-intensity ratios on T2-weighted spin-echo images and the adrenal/liver T2 relaxation-time ratios showed similar inherent discriminatory capacity. Overlap remains despite the use of these parameters. On the basis of this preliminary information, we conclude that MR has merit for the characterization of adrenal masses at 1.5 T. T2 relaxation time of the adrenal mass shows the greatest promise for discriminating nonadenomas from adenomas.

    View details for Web of Science ID A1989AG02100018

    View details for PubMedID 2750617

  • HERNIATION PITS OF THE FEMORAL-NECK - APPEARANCE AT MR IMAGING RADIOLOGY NOKES, S. R., Vogler, J. B., Spritzer, C. E., Martinez, S., Herfkens, R. J. 1989; 172 (1): 231-234

    Abstract

    Herniation pits of the femoral neck are benign lesions recognized because of their characteristic appearance and location on plain radiographs. The appearance of this lesion in seven magnetic resonance (MR) examinations of the hips in five patients is described. MR revealed a well-marginated, round to oval defect in the superior lateral quadrant of the femoral neck with anterior cortical extension in all cases. With T1 weighting the signal intensity within each lesion was uniformly low. All but one case revealed a peripheral margin of absent signal intensity on T2-weighted and out-of-phase images. The MR appearance and location are sufficiently characteristic to allow identification of this lesion and aid in differentiating it from pathologic processes such as avascular necrosis, with which it may be confused.

    View details for Web of Science ID A1989AB75000047

    View details for PubMedID 2740509

  • CEREBRAL ATROPHY IN ANOREXIA-NERVOSA - A PILOT-STUDY BIOLOGICAL PSYCHIATRY HOFFMAN, G. W., Ellinwood, E. H., ROCKWELL, W. J., Herfkens, R. J., NISHITA, J. K., GUTHRIE, L. F. 1989; 26 (3): 321-324

    View details for Web of Science ID A1989AB09900013

    View details for PubMedID 2742947

  • CEREBRAL ATROPHY IN BULIMIA BIOLOGICAL PSYCHIATRY HOFFMAN, G. W., Ellinwood, E. H., ROCKWELL, W. J., Herfkens, R. J., NISHITA, J. K., GUTHRIE, L. F. 1989; 25 (7): 894-902

    Abstract

    The extent of cerebral atrophy in 8 consecutively chosen unmedicated bulimics and 8 normal controls was determined by magnetic resonance imaging. There was no history of anorexia nervosa or alcoholism in either group. Measures obtained included the ratio of cerebral to cranial area at the midsagittal section, as well as maximum ventricle/brain ratio in the axial plane. Sagittal cerebral/cranial ratio was significantly less in the bulimic group than in controls [0.82 +/- 0.04 (SD) versus 0.90 +/- 0.03, Z = -2.74, p = 0.006, two-tailed Mann-Whitney U-test], whereas ventricle/brain ratio was not significantly different between groups. Implications for the occurrence of cortical atrophy in normal-weight bulimics, as well as for the relative absence of ventricular enlargement in these patients, are discussed.

    View details for Web of Science ID A1989U234400009

    View details for PubMedID 2720004

  • FLUID SHEAR AND SPIN-ECHO IMAGES MAGNETIC RESONANCE IN MEDICINE Kuethe, D. O., Herfkens, R. J. 1989; 10 (1): 57-70

    Abstract

    Because clinical studies have indicated that shear in fluids may be one of the major causes of magnetic resonance image artifacts, we imaged an apparatus that would separate the effects of shear from the plethora of other motion artifacts. The apparatus contained fluid between two concentric cylinders. To produce shear, we turned the outer cylinder. To produce motion without shear, we turned both cylinders as one. Shear rates near 200 s-1 (similar to those in large arteries) can cause pixel intensities either to increase 40% or decrease to background levels. Increases can occur when the velocities are nearly parallel to the phase-encoding gradient. Decreases can occur when velocities are in the direction of the frequency gradient. The decreases are similar to those predicted from phase dispersion within a "voxel" so long as the voxel's phase warp does not exceed 2 pi.

    View details for Web of Science ID A1989U147600005

    View details for PubMedID 2755334

  • EVALUATION OF FLOW THROUGH SIMULATED VASCULAR STENOSES WITH GRADIENT ECHO MAGNETIC-RESONANCE IMAGING INVESTIGATIVE RADIOLOGY PODOLAK, M. J., Hedlund, L. W., Evans, A. J., Herfkens, R. J. 1989; 24 (3): 184-189

    Abstract

    Magnetic resonance imaging using gradient echo sequences can quickly generate dynamic images of the cardiovascular system. We used a gradient echo sequence (repetition time = 21 milliseconds, echo time = 12 milliseconds, flip angle = 30 degrees) to evaluate how a simulated vascular stenoses affects the signal intensity of flowing fluid. Axial slices were obtained at regular intervals along a plastic tube containing a circular constriction (25%, 51%, or 73% reduction of cross-sectional area). Image data collected at each slice level were used to reconstruct 32 images evenly spaced in time over one cycle of pulsatile flow. Contrast ratios were calculated between signal intensities from tube lumen and surrounding stationary water jacket. Upstream from each stenosis, signal intensity increased during systole and decreased during diastole, paralleling the changes in velocity we measured with a flow probe. However, within the 51% and 73% stenoses and just beyond them, there were consistent decreases in systolic signal intensity. Flow through the 25% constriction had little effect on the signal intensity pattern. These results suggest that the gradient echo pulse sequence may be useful in evaluating disturbed flow associated with vascular stenoses.

    View details for Web of Science ID A1989T670100001

    View details for PubMedID 2753632

  • CINE GRADIENT-REFOCUSED MR IMAGING OF CENTRAL PULMONARY EMBOLI AMERICAN JOURNAL OF ROENTGENOLOGY POSTERARO, R. H., Sostman, H. D., Spritzer, C. E., Herfkens, R. J. 1989; 152 (3): 465-468

    Abstract

    We studied the use of MR imaging with a limited-flip-angle, gradient-refocused pulse sequence to show central pulmonary emboli in 11 patients and to distinguish acute from chronic emboli. The central pulmonary vasculature was imaged by using a cine-limited-flip-angle (cine-MR) pulse sequence with 63/13 (TR/TE) and a 30 degrees flip angle (theta), as well as standard spin-echo sequences. Patients were selected on the basis of suspicion of central pulmonary embolism and correlative studies done within 24 hr of the MR examination. Correlations with other studies were based on the original MR report and blinded review of the MR images by two observers in consensus. Emboli were shown in all cases by cine-MR, and they corresponded to the locations of angiographic abnormalities and mismatched perfusion defects on scintigraphy. In three patients considered to have acute pulmonary embolus on the basis of angiography, the cine-MR studies were consistent with acute pulmonary embolus in two patients and chronic pulmonary embolus in one patient (however, in that patient pathologic examination showed chronic embolism). In one case in which angiography led to the diagnosis of acute and chronic pulmonary embolism, the cine-MR study showed acute embolism. In three patients thought to have chronic pulmonary embolus on the basis of angiography, the cine-MR study was interpreted as representing acute embolus in one patient and chronic embolus in two patients. In this highly selected, small group of patients, cine-MR imaging was accurate in showing central pulmonary embolism.

    View details for Web of Science ID A1989T281800005

    View details for PubMedID 2783797

  • CHEMICAL-SHIFT IMAGING OF ATHEROSCLEROSIS AT 7.0-TESLA INVESTIGATIVE RADIOLOGY Maynor, C. H., Charles, H. C., Herfkens, R. J., Suddarth, S. A., Johnson, G. A. 1989; 24 (1): 52-60

    Abstract

    Chemical shift imaging (CSI) was performed on cadaveric atherosclerotic fibrous plaques, periaortic adipose tissue, and cholesterol standards using a 7.0 Tesla horizontal bore prototype imaging spectrometer. Proton spectroscopy of intact tissue and deuterated chloroform extracted samples was done at the equivalent field strength of 7.0 Tesla on a vertical bore spectrometer, including studies of temperature dependence and T2 relaxation measurements. Spectra obtained using CSI on the imaging magnet were comparable with those from the conventional vertical spectrometer. Fibrous plaques and adipose tissue had unique spectral features, differing in the ratios of their water and various fat components. Chloroform extractions revealed a typical cholesteric ester spectrum for the fibrous plaque in contrast to the triglyceride spectrum of the adipose tissue. These two tissues also had different T2 relaxation measurements of their major fat resonances, with fibrous plaques having a short T2 compared to adipose tissue (15.9 milliseconds vs. 46.2 milliseconds). Temperature dependence studies showed that spectral signal intensity of the fat resonance of the fibrous plaque increased while linewidth decreased with increasing temperature from 24 degrees C to 37 degrees C. Atherosclerotic lesions may be studied at 7.0 Tesla, and NMR parameters defined in the present study may be used for further studies at other magnetic field strengths.

    View details for Web of Science ID A1989R896500011

    View details for PubMedID 2917823

  • VASCULAR MORPHOLOGY BY 3-DIMENSIONAL MAGNETIC-RESONANCE IMAGING MAGNETIC RESONANCE IMAGING Cline, H. E., Lorensen, W. E., Herfkens, R. J., Johnson, G. A., Glover, G. H. 1989; 7 (1): 45-54

    Abstract

    A three-dimensional examination of blood vessels is provided using MR data from seven cases. The vascular surfaces are constructed with an algorithm that automatically follows the selected artery or vein and generates a projected three-dimensional gradient shaded image. Fast 3DFT pulse sequences were optimized to enhance the time-of-flight contrast of the intravascular region. By increasing the surface threshold value in a three-dimensional head study, the flesh of a patient's face was peeled away to demonstrate the superfacial temporal artery. Gated cardiac images show the great vessels and cardiac chambers. A three-dimensional view of the aorta shows an irregular surface in the vicinity of an adrenal tumor. 3D MR exams provide a non-invasive technique for assessing vascular morphology in a clinical setting.

    View details for Web of Science ID A1989T403600006

    View details for PubMedID 2918818

  • FAST LIMITED FLIP ANGLE MR SUBTRACTION ANGIOGRAPHY MAGNETIC RESONANCE IN MEDICINE Tasciyan, T. A., Lee, J. N., Riederer, S. J., DECASTRO, J. B., Hedlund, L. W., Herfkens, R. J., Spritzer, C. E. 1988; 8 (3): 261-274

    Abstract

    A fast MR angiography method is introduced that is capable of generating difference images of blood vessels in scan times of 10-20 s. This is an order of magnitude faster than many previous methods. The fundamental concept of this approach is to use cardiac gating and acquire several phase encodings at least twice during each cardiac cycle using limited flip angles (LFAs) and repetition times in the 20 to 50 ms range. The encodings acquired during diastole are subtracted from those acquired during systole to generate the difference image. The contrast in the difference image is due both to the influx of unsaturated spins and to the loss of phase coherence of systolic blood moving at high velocity along a magnetic gradient. The systolic peak of the cardiac cycle is determined during reconstruction by shifting the systolic and diastolic "windows" until the difference signal is maximized. Ghost artifacts due to pulsatile flow are eliminated by a phase reordering technique similar in concept to those developed for suppression of breathing artifacts. Arteries in thick slices are successfully imaged and initial in vivo results are presented.

    View details for Web of Science ID A1988R055000003

    View details for PubMedID 3060701

  • HEPATIC ADENOMA - MR APPEARANCE MIMICKING FOCAL NODULAR HYPERPLASIA JOURNAL OF COMPUTER ASSISTED TOMOGRAPHY NOKES, S. R., Baker, M. E., Spritzer, C. E., Meyers, W., Herfkens, R. J. 1988; 12 (5): 885-887

    Abstract

    A hepatic adenoma (HA) nearly isointense to normal liver on short and long repetition and echo time spin echo pulse sequences is presented. Contrary to previous expectations, the case shows that a single hepatic mass with these signal characteristics on magnetic resonance without a scar may represent either HA or focal nodular hyperplasia.

    View details for Web of Science ID A1988Q343900034

    View details for PubMedID 2844864

  • EFFECT OF MAGNETIC-RESONANCE IMAGING ON XENOPUS-LAEVIS EMBRYOGENESIS MAGNETIC RESONANCE IMAGING Kay, H. H., Herfkens, R. J., Kay, B. K. 1988; 6 (5): 501-506

    Abstract

    Xenopus laevis embryos, exposed to various lengths of magnetic resonance imaging (MRI), demonstrated no abnormal morphology, function, or developmental delays. The overall protein profiles and nucleic acid ratios were similar compared to controls. Results suggest there are no adverse effects of MRI components on the development of this vertebrate.

    View details for Web of Science ID A1988Q293900004

    View details for PubMedID 2465471

  • MR FLUOROSCOPY - TECHNICAL FEASIBILITY MAGNETIC RESONANCE IN MEDICINE Riederer, S. J., Tasciyan, T., Farzaneh, F., Lee, J. N., Wright, R. C., Herfkens, R. J. 1988; 8 (1): 1-15

    Abstract

    A method of magnetic resonance image acquisition and reconstruction is described in which high imaging rates and fast reconstruction times are allowed. The acquisition is a modification of the basic FLASH sequence but with a restricted number N of phase encodings. The encodings are applied sequentially, periodically, and continuously. Images are formed by sliding a window of width N encodings along the acquired data and reconstructing an image for each position of the window. In general the acquisition time per image exceeds the time between successive images, and the method thus has a temporal lag. Experimental studies were performed with a dynamic phantom using 48 phase encodings and a TR of 20 ms, for an image acquisition time of about 1 s. The image display rate in the reconstructed sequence was 12.5 images/s, and the image sequence portrayed the motion of the phantom. Additional studies were done with 24 encodings. It is shown how the sliding window technique lends itself to high-speed reconstruction, with each newly acquired echo used to quickly update the image on display. The combination of the acquisition technique described and a hardware implementation of the reconstruction algorithm can result in realtime MR image acquisition and reconstruction.

    View details for Web of Science ID A1988Q076100001

    View details for PubMedID 3173063

  • A CARDIAC PHANTOM AND PULSATILE FLOW PUMP FOR MAGNETIC-RESONANCE IMAGING STUDIES INVESTIGATIVE RADIOLOGY Evans, A. J., Hedlund, L. W., Herfkens, R. J. 1988; 23 (8): 579-583

    Abstract

    Fast scan magnetic resonance imaging (MRI) acquisitions are a rapid noninvasive means of evaluating the cardiovascular system. Because the appearance of flowing blood is highly variable, the interpretation of these images is sometimes difficult. A nonferromagnetic phantom that could generate lifelike pulsatile flow and also simulate the motions of the beating heart would facilitate image interpretation. This paper describes an MRI-compatible cardiovascular phantom that mimics the motions of the heart and also creates physiologic pulsatile flow. The phantom consists of a ventricle and an air pump that drives it. The pump is connected to the ventricle with seven meters of air hose so that the pump (which has ferromagnetic parts) can be placed outside the magnet room. The ventricle is placed in an airtight Plexiglas cylinder and the pump alternately pressurizes and depressurizes the cylinder, driving fluid in and out of the ventricle. The motions of the ventricular wall simulate the motions of the heart, and the pulsatile flow generated is of physiologic velocities and volumes. This phantom also can be used with other methods of evaluating cardiovascular function, such as MUGAS, angiography, and Doppler, allowing correlation between MRI and other modalities. Finally, the phantom can be used to study almost any aspect of cardiovascular function from pulsatile flow velocity to ventricular studies (ejection fractions, cardiac output, wall motion) and even studies of stenotic or regurgitant valves.

    View details for Web of Science ID A1988P526200006

    View details for PubMedID 3417435

  • VALVULAR REGURGITATION - DYNAMIC MR IMAGING RADIOLOGY UTZ, J. A., Herfkens, R. J., HEINSIMER, J. A., Shimakawa, A., Glover, G., Pelc, N. 1988; 168 (1): 91-94

    Abstract

    Cine magnetic resonance (MR) imaging is a new technique that combines short repetition times, limited flip angles, gradient refocused echoes, and cardiac gating. This technique has a temporal resolution of up to 32 time frames per cardiac cycle and accentuates signal from flowing blood. Cine MR images of 56 valves in 27 patients were evaluated and compared with either Doppler echocardiograms or cardiac catheterization images. An area of decreased signal that correlated spatially and temporally with regurgitant blood flow was seen in all instances in which valvular incompetence was demonstrated on either Doppler echocardiograms or cardiac catheterization images (20 valves). This abnormality was seen in nine of 36 cases without valvular incompetence. Cine MR imaging may be sensitive to turbulence and thus sensitive to valvular regurgitation.

    View details for Web of Science ID A1988N942700016

    View details for PubMedID 3380987

  • EFFECTS OF TURBULENCE ON SIGNAL INTENSITY IN GRADIENT ECHO IMAGES INVESTIGATIVE RADIOLOGY Evans, A. J., Blinder, R. A., Herfkens, R. J., Spritzer, C. E., Kuethe, D. O., Fram, E. K., Hedlund, L. W. 1988; 23 (7): 512-518

    Abstract

    Although the appearance of laminar vascular flow in magnetic resonance (MR) images has been characterized, there is no general agreement about the effect of turbulent flow on MR signal intensity. This study uses a fast scan gradient echo pulse sequence to evaluate nonpulsatile turbulent flow in two different models. The first model simulated flow in normal vascular structure. It generated nonpulsatile, laminar and turbulent flow in straight, smooth-walled Plexiglas tubes. The second model simulated flow through a vascular stenosis. It generated nonpulsatile, laminar, and turbulent flow through an orifice. Velocities and flow rates ranged from low physiologic to well above the physiologic range (velocity = .3 to 280 cm/second, flow rate from .15 to 40 L/minute). Transition from laminar to turbulent flow was observed with dye streams. Turbulent flow in straight, smooth-walled vessels was not associated with a decrease in MR signal intensity even at the highest velocities and flow rates studied. The transition from laminar to turbulent flow through an orifice is not associated with a decrease in gradient echo signal intensity. As the intensity of the turbulent flow increases, however, there is a threshold above which signal intensity decreases linearly as turbulence increases (r = .97). This study suggests that flow in normal vascular structures should not be associated with decreased signal intensity in gradient echo images. Turbulent flow through areas such as valves, valvular lesions or vascular stenoses, may be associated with a decrease in gradient echo signal intensity.

    View details for Web of Science ID A1988P317300005

    View details for PubMedID 3170139

  • EFFECTS OF ECT ON BRAIN STRUCTURE - A PILOT PROSPECTIVE MAGNETIC-RESONANCE IMAGING STUDY AMERICAN JOURNAL OF PSYCHIATRY Coffey, C. E., Figiel, G. S., DJANG, W. T., SULLIVAN, D. C., Herfkens, R. J., Weiner, R. D. 1988; 145 (6): 701-706

    Abstract

    The authors describe a pilot prospective investigation of the effects of ECT on brain structure using magnetic resonance imaging (MRI). In nine patients with major depression, a course of ECT produced no acute changes in brain structure according to blind raters' assessments of cortical atrophy and global comparison of pre- and post-ECT studies. There were also no significant changes in the ventricle-brain ratios. Pre-ECT brain abnormalities were common in these patients yet were also unaffected by ECT. Future MRI studies of ECT should include more subjects and should address long-term changes and subtle brain abnormalities.

    View details for Web of Science ID A1988N596200007

    View details for PubMedID 3369556

  • EFFICIENT PULSE SEQUENCE FOR MULTISECTION DUAL REPETITION TIME MR IMAGE ACQUISITION RADIOLOGY Farzaneh, F., Riederer, S. J., DJANG, W. T., Curnes, J. T., Herfkens, R. J. 1988; 167 (2): 541-546

    Abstract

    A magnetic resonance imaging pulse sequence was developed in which multisection spin-echo image data are simultaneously acquired for two repetition time (TR) intervals (TR1 and TR2) in one imaging sequence. In a conventional multisection image at a single TR, the number of sections is limited to TR/TS, where TS is the readout time. With this new sequence, the number of sections that can be imaged at both TRs in one acquisition is equal to (TR1 + TR2)/(TS1 + TS2), where TS1 and TS2 may be different for the two TRs. Imaging time is equal to that for a single image at a TR of TR1 + TR2. Clinical images were obtained with the new sequence from 15 patients and compared with images acquired at the same TR/TE by means of standard multisection single-TR methods. Relative image quality was assessed by three radiologists in 37 comparisons. In general, the dual-TR results at the long TR were judged equivalent to those from a single-TR image. Dual-TR results at the short TR had a modest reduction in contrast, but in none of 15 cases were any pathologic features missed.

    View details for Web of Science ID A1988N010900057

    View details for PubMedID 3357969

  • MR IMAGING OF THE KNEE - PRELIMINARY-RESULTS WITH A 3DFT GRASS PULSE SEQUENCE AMERICAN JOURNAL OF ROENTGENOLOGY Spritzer, C. E., Vogler, J. B., Martinez, S., Garrett, W. E., Johnson, G. A., McNamara, M. J., Lohnes, J., Herfkens, R. J. 1988; 150 (3): 597-603

    Abstract

    The knees of 17 patients (18 extremities) with possible meniscal, cruciate ligament, and articular cartilage abnormalities were examined with a three-dimensional Fourier transform (3DFT), gradient-refocused acquisition in a steady state (GRASS) pulse sequence. Arthroscopic confirmation was available in all cases and was the standard for comparison. Thirteen of these extremities were also examined by using a two-dimensional Fourier transform spin-echo pulse sequence with a 2000-msec repetition time and 20- and 80-msec echo time. In these 13 cases, both pulse sequences correctly identified seven of eight meniscal abnormalities. However, interpretation of the 3DFT GRASS images resulted in fewer false-positive meniscal tears (three vs six). Cruciate ligament tears were detected more readily on the 3DFT GRASS images (six vs three with two possible tears on the spin-echo images). These preliminary findings suggest that the overall accuracy of MR imaging of the knee could be improved by including 3DFT gradient-refocused pulse sequences.

    View details for Web of Science ID A1988M239300026

    View details for PubMedID 3257617

  • MR SUBTRACTION ANGIOGRAPHY WITH A MATCHED-FILTER JOURNAL OF COMPUTER ASSISTED TOMOGRAPHY DECASTRO, J. B., Tasciyan, T. A., Lee, J. N., Farzaneh, F., Riederer, S. J., Herfkens, R. J. 1988; 12 (2): 355-362

    Abstract

    The technique of matched filtering (MF) has been used in the past with X-ray digital subtraction angiography as a method of improving signal-to-noise ratio (SNR) in subtraction angiographic images. In this work we describe how MF can be applied to a series of images produced by cinematographic magnetic resonance (cine MR) to produce angiographic images. Likewise, a simple subtraction image can be formed by subtracting an image in which flow is not well visualized from an image at the same location but with flow visualization. Theory predicts that a subtraction image resulting from the MF technique will yield typical SNR improvements of 60% over results from simple subtraction. Twenty-one studies of the human popliteal, canine aorta, and canine carotid artery were undertaken in which MF was compared with simple subtraction. It was determined that cine MR can be used to produce subtraction angiographic images and that MF can produce a modest improvement in SNR over simple subtraction.

    View details for Web of Science ID A1988M543100037

    View details for PubMedID 3280628

  • DEEP VENOUS THROMBOSIS EVALUATION WITH LIMITED-FLIP-ANGLE, GRADIENT-REFOCUSED MR IMAGING - PRELIMINARY EXPERIENCE RADIOLOGY Spritzer, C. E., Sussman, S. K., Blinder, R. A., Saeed, M., Herfkens, R. J. 1988; 166 (2): 371-375

    Abstract

    Sixteen patients (17 lower extremities) were prospectively examined with venography and limited-flip-angle, gradient-refocused magnetic resonance (MR) imaging for the presence or absence of deep venous thrombosis. Thrombosed vessels showed decreased-to-absent signal intensity, while patent vessels had high signal intensity. In 16 of 17 extremities, MR images allowed accurate detection and localization of the thrombi found with venography. In the remaining extremity, MR imaging allowed correct identification of thrombus in the iliac and femoral veins but incorrectly demonstrated clot in the calf and popliteal veins. MR imaging with limited-flip-angle, gradient-refocused pulse sequences appears to be a sensitive, noninvasive means of detecting deep venous thrombosis.

    View details for Web of Science ID A1988L722500013

    View details for PubMedID 3336713

  • Magnetic resonance imaging of the heart. Magnetic resonance annual Spritzer, C. E., Herfkens, R. J. 1988: 217-244

    View details for PubMedID 3079297

  • ALTERED PHOSPHATE-METABOLISM IN MYOCARDIAL-INFARCTION - P-31 MR SPECTROSCOPY RADIOLOGY Bottomley, P. A., Herfkens, R. J., Smith, L. S., Bashore, T. M. 1987; 165 (3): 703-707

    Abstract

    The high-energy myocardial phosphate metabolism of four patients with acute anterior myocardial infarction after coronary angioplasty and drug therapy was evaluated with cardiac-gated phosphorus magnetic resonance (MR) depth-resolved surface coil spectroscopy (DRESS) 5-9 days after the onset of symptoms. Significant reductions (about threefold) in the phosphocreatine (PCr) to inorganic phosphate (Pi) ratio and elevations in the Pi to adenosine triphosphate (ATP) ratio were observed in endocardially or transmurally derived MR spectra when compared with values from epicardially displaced spectra and values from seven healthy volunteers (P less than .05). High-energy phosphate metabolites and Pi ratios did not vary significantly during the cardiac cycle in healthy volunteers. However, contamination of Pi resonances by phosphomonoester components, including blood 2,3-diphosphoglycerate, precluded accurate spectral quantification of Pi and pH. The results indicate that localized P-31 MR spectroscopy may be used to directly assess cellular energy reserve in clinical myocardial infarction and to evaluate metabolic response to interventions.

    View details for Web of Science ID A1987K986100022

    View details for PubMedID 2961004

  • MAGNETIC-RESONANCE-IMAGING IN MULTIPLE-SCLEROSIS - DECREASED SIGNAL IN THALAMUS AND PUTAMEN ANNALS OF NEUROLOGY Drayer, B. P., Burger, P., Hurwitz, B., Dawson, D., Cain, J., Leong, J., Herfkens, R., Johnson, G. A. 1987; 22 (4): 546-550

    Abstract

    High-field strength (1.5 Tesla) magnetic resonance imaging in 15 patients with multiple and extensive white-matter lesions and clinically definite multiple sclerosis delineated a previously undescribed finding of abnormally decreased signal intensity on T2-weighted images in the thalamus and putamen. The decreased signal intensity (preferential decreased T2 relaxation time) is most likely to be related to abnormally increased iron accumulation causing local magnetic field heterogeneities.

    View details for Web of Science ID A1987K570600016

    View details for PubMedID 3435073

  • MR IMAGING WITH SURFACE COILS IN PRIMARY HYPERPARATHYROIDISM JOURNAL OF COMPUTER ASSISTED TOMOGRAPHY Kier, R., Blinder, R. A., Herfkens, R. J., Leight, G. S., Spritzer, C. E., Carroll, B. A. 1987; 11 (5): 863-868

    Abstract

    The use of magnetic resonance (MR) to preoperatively evaluate patients with primary hyperparathyroidism was assessed using a 1.5 T system and surface coil reception. Twenty-five patients with primary hyperparathyroidism were studied before surgical exploration. Axial images, 5 mm thick, were obtained from the thyroid cartilage to the sternal notch. Both T1-weighted [short repetition time (TR), short echo time (TE)] and T2-weighted (long TR, long TE) spin echo sequences were performed in most cases. Parathyroid adenomas typically demonstrated greater signal than surrounding tissues on T2-weighted sequences, yet demonstrated signal intensity that was less than or equal to normal thyroid tissue on T1-weighted sequences. Using these criteria, MR correctly identified 17 of 20 surgically proven parathyroid adenomas in the neck. Magnetic resonance appeared less sensitive in two patients with parathyroid hyperplasia, identifying only one of six hyperplastic glands. We conclude that MR with surface coils provides high contrast, anatomic delineation of the neck and is useful for preoperative localization of parathyroid tumors.

    View details for Web of Science ID A1987J992600023

    View details for PubMedID 3655050

  • THE FATE OF INORGANIC-PHOSPHATE AND PH IN REGIONAL MYOCARDIAL-ISCHEMIA AND INFARCTION - A NONINVASIVE P-31 NMR-STUDY MAGNETIC RESONANCE IN MEDICINE Bottomley, P. A., Smith, L. S., BRAZZAMANO, S., Hedlund, L. W., REDINGTON, R. W., Herfkens, R. J. 1987; 5 (2): 129-142

    Abstract

    To determine the characteristic appearance of phosphorus (31P) nuclear magnetic resonance spectra in acute and chronic myocardial infarction in situ, cardiac-gated depth-resolved surface coil spectroscopy (DRESS) at 1.5 T was used to monitor 31P NMR spectra from localized volumes in the left anterior canine myocardium for up to 5 days following permanent occlusion of the left anterior descending coronary artery. Coronary occlusion initially produced regional ischemia manifested as significant reductions in the phosphocreatine (PCr) to inorganic phosphate (Pi) ratios and intracellular pH (P less than 0.05, Student's t test) in endocardially displaced spectra acquired in periods as short as 50 to 150 s postocclusion. Spectra acquired subsequently revealed either (i) restoration of near-normal phosphate metabolism sometime between 10 and about 50 min postocclusion or (ii) advancing ischemic phosphate metabolism at about an hour postocclusion, and/or (iii) maintenance of depressed PCr/Pi ratios for up to 5 days postocclusion with a return of the apparent pH to near normal values between 6 and 15 h postocclusion. Postmortem examination of animals exhibiting the first type of behavior revealed the existence of coronary collateral vessels. The last type of behavior indicates that Pi remains substantially localized in damaged myocardium for days following infarction. The location and size of infarctions were determined postmortem by staining excised hearts. The smallest infarctions detected by 31P DRESS weighed 4.9 and 7.5 g. The most acidic pH measured in vivo was 5.9 +/- 0.2. Infarctions aged 1/2 day to 5 days were characterized by elevated but broad Pi resonances at 5.1 +/- 0.2 ppm relative to PCr and significantly depressed PCr/Pi ratios (P less than 0.002, Student's t test) relative to preocclusion values. Contamination of Pi resonances by phosphomonoester (PM) components is a significant problem for preocclusion Pi and pH measurements. These results should be applicable to the detection and identification of human myocardial infarction using 31P NMR and DRESS.

    View details for Web of Science ID A1987J486200004

    View details for PubMedID 3657502

  • BENIGN ADRENAL LESIONS MIMICKING MALIGNANCY ON MR IMAGING - REPORT OF 2 CASES RADIOLOGY Baker, M. E., SPRITZER, C., Blinder, R., Herfkens, R. J., Leight, G. S., Dunnick, N. R. 1987; 163 (3): 669-671

    Abstract

    Two cases of nonmalignant adrenal masses with prolonged T2 relaxation time and increased adrenal/liver signal ratios are reported. These two cases, one a functioning adenoma with small areas of hemorrhage and the other tuberculosis, emphasize that increased signal intensity in an adrenal mass on T2-weighted images is not always due to malignancy or a pheochromocytoma. While the signal characteristics of an adrenal mass are useful in distinguishing malignancy or pheochromocytoma from benign adenomas, other studies (such as computed tomography for the detection of hemorrhage), clinical evaluation, and percutaneous biopsy remain useful in the investigation of an adrenal mass.

    View details for Web of Science ID A1987H293600015

    View details for PubMedID 3575711

  • WORK IN PROGRESS - INVITRO ANALYSIS OF PLEURAL FLUID ANALOGS BY PROTON MAGNETIC-RESONANCE - PRELIMINARY STUDIES AT 1.5T INVESTIGATIVE RADIOLOGY Vock, P., Hedlund, L. W., Herfkens, R. J., Effmann, E. L., Brown, M. A., Putman, C. E. 1987; 22 (5): 382-387

    Abstract

    To test the potential of 1.5 Tesla magnetic resonance imaging (MRI) for assessing the protein concentration of pleural effusions, five pleural fluid analogs (saline + 0, 2, 4, 6, 8 g albumin/100 mL) and, for comparison, four saline dilutions of whole blood were evaluated in vitro. The relaxation rates (1/T1, 1/T2) of albumin solutions were determined by 1.5 T spectroscopy (MRS) and correlated with albumin concentration (1/T1:slope 0.02, r + 0.89, P less than .05; 1/T2: slope 0.16, r = 0.997, P less than .001). MRI studies of these solutions showed no significant correlation with 1/T1, but 1/T2 showed a positive correlation with albumin concentration (r = 0.98, P less than .01). Both MRI relaxation rates were significantly correlated with blood concentration, and slopes were greater than for albumin solutions. These preliminary studies, demonstrating differences in correlation between relaxation rates and the concentration of albumin and blood, suggest that MRI has the potential for differentiating pleural effusions of different chemical composition.

    View details for Web of Science ID A1987H366400005

    View details for PubMedID 3597006

  • CINE MR DETERMINATION OF LEFT-VENTRICULAR EJECTION FRACTION AMERICAN JOURNAL OF ROENTGENOLOGY UTZ, J. A., Herfkens, R. J., HEINSIMER, J. A., Bashore, T., Califf, R., Glover, G., Pelc, N., Shimakawa, A. 1987; 148 (5): 839-843

    Abstract

    Cine MR imaging provides tomographic images of the heart with both high spatial and high temporal resolution. As many as 32 images per cardiac cycle can be acquired with up to four separate anatomic slices and a total imaging time of 128 cardiac cycles. End-diastolic and end-systolic volumes were determined in 11 patients, and ejection fractions were calculated. The results correlated linearly with those from cardiac catheterization (correlation coefficient of .88). We conclude that cine MR imaging can be used to obtain quantitative information about the heart and has the potential to become a valuable noninvasive means of cardiac evaluation.

    View details for Web of Science ID A1987G945000001

    View details for PubMedID 3495115

  • 2-SECOND MR IMAGES - COMPARISON WITH SPIN-ECHO IMAGES IN 29 PATIENTS AMERICAN JOURNAL OF ROENTGENOLOGY UTZ, J. A., Herfkens, R. J., Johnson, C. D., Shimakawa, A., Pelc, N., Glover, G., Johnson, G. A., Spritzer, C. E. 1987; 148 (3): 629-633

    Abstract

    MR images can be obtained with a 2-sec scan time when an extremely short repetition rate (22 msec), limited flip angle (30 degrees), and gradient refocused echoes are used. Comparison of 415 such images obtained in 29 patients with routine T1-weighted (TR 500, TE 25) and T2-weighted (TR 2000, TE 80) images showed that images free of respiratory artifacts could be obtained in all patients. Although abdominal organs were well seen with 2-sec scan time, overall evaluation of these organs was better on routine T1-weighted images. Vascular structures, however, were seen as well or better on the 2-sec images in 60% of cases. The images were extremely sensitive to field nonhomogeneity, and metallic artifact was exaggerated in five patients with surgical clips. Two-sec MR images provide a rapid method of localizing abdominal organs for further evaluation. The sensitivity to blood flow may assist in the assessment of vascular patency.

    View details for Web of Science ID A1987G131300036

    View details for PubMedID 3492897

  • EVALUATION OF STEADY AND PULSATILE FLOW WITH DYNAMIC MRI USING LIMITED FLIP ANGLES AND GRADIENT REFOCUSED ECHOES MAGNETIC RESONANCE IMAGING Evans, A. J., Hedlund, L. W., Herfkens, R. J., UTZ, J. A., Fram, E. K., Blinder, R. A. 1987; 5 (6): 475-482

    Abstract

    Magnetic resonance imaging sequences utilizing limited flip angles and gradient echoes yield rapid (less than 2 min) dynamic images of the cardiovascular system. These images contain both accurate anatomical and functional information. Using a gradient refocused acquisition in the steady state (GRASS) in the CINE mode, we studied the relationship between gradient echo signal intensity and velocity of steady and pulsatile flow in a phantom simulating medium to large vessels. Images were acquired on a 1.5 Tesla system (repetition time = 21 ms, echo time = 12 ms, flip angle = 30 degrees). Data from each pulse interval were sorted in 16 images. Signal intensities from flow tube lumina and surrounding stationary water jacket were used to calculate contrast ratios which were compared to velocity measurements made with electromagnetic (EM) flow probes outside the magnet room. During steady flow, signal intensity contrast ratios increased with increasing flow and in a 10 mm thick slice, reached a peak at 48 cm/s, and declined for velocities up to 90 cm/s. Changes in instantaneous velocity during pulsatile flow correlated well (r greater than .88) with signal intensity changes up to a maximum mean velocity of 17 cm/s. Total signal intensity from the lumen for an "R to R" interval correlated extremely well (r greater than .97) with mean pulsatile flow velocities up to 30 cm/s. The excellent correlation between gradient echo signal intensity and actual flow velocities suggests that this imaging sequence might be useful for evaluating normal and pathologic flow phenomena.

    View details for Web of Science ID A1987L483100008

    View details for PubMedID 3431358

  • OPTIMIZING ELECTROCARDIOGRAPH ELECTRODE PLACEMENT FOR CARDIAC-GATED MAGNETIC-RESONANCE-IMAGING INVESTIGATIVE RADIOLOGY Dimick, R. N., Hedlund, L. W., Herfkens, R. J., Fram, E. K., Utz, J. 1987; 22 (1): 17-22

    Abstract

    Electrocardiographs recorded in a magnetic field for cardiac-gating in magnetic resonance imaging (MRI) are complicated by blood flow-induced potentials. This study examines which lead of the standard 12-lead ECG maximizes the QRS while minimizing flow-induced interference. Twelve-lead ECGs were performed on normal volunteers (n = 9) and patients (n = 13) in and out of the bore of a 1.5 Tesla imaging magnet. The amplitude of the major flow-induced potentials was measured, and the vectors of largest induced potential and the QRS axis were plotted for each subject. ECGs obtained outside and inside the magnet were digitized and subtracted (in magnet ECG--out of magnet ECG = artifact ECG) and the peaks of the resultant curves measured. Superimposed potentials were largest in the early T wave and late S-T segment in leads I, II, V1, and V2, and smallest in III and AVF. A low-amplitude 7-to 10-Hz signal occurred in most leads. In the frontal plane, QRS axes and flow potential vectors were closely clustered. In the transverse plane, QRS axes generally followed leads V5 or V6, whereas the flow potential vectors followed leads V1, V2, or V3. The normal and patient groups did not differ. Although leads III and AVP showed the smallest superimposed potentials, V5, V6, or a left posterior chest lead may maximize QRS and reduce artifact most consistently. A 7- to 10-Hz frequency filter may help eliminate artifacts in some subjects.

    View details for Web of Science ID A1987F670400002

    View details for PubMedID 3818232

  • RAPID CALCULATION OF T1 USING VARIABLE FLIP ANGLE GRADIENT REFOCUSED IMAGING MAGNETIC RESONANCE IMAGING Fram, E. K., Herfkens, R. J., Johnson, G. A., Glover, G. H., Karis, J. P., Shimakawa, A., PERKINS, T. G., Pelc, N. J. 1987; 5 (3): 201-208

    Abstract

    We present a method for rapid measurement of T1 relaxation times using gradient refocused images at limited flip angles and short repetition times. This "variable nutation" techniques was investigated using a T1 phantom. There was a high correlation between measurements obtained with the variable nutation and partial saturation techniques. The ability of this method to create calculated T1 images is also demonstrated. We conclude that the variable nutation method may allow measurement of T1 relaxation times with a significant reduction in acquisition time compared to partial saturation techniques.

    View details for Web of Science ID A1987J432400007

    View details for PubMedID 3626789

  • MRI WITH SURFACE COILS FOR PARATHYROID TUMORS - PRELIMINARY INVESTIGATION AMERICAN JOURNAL OF ROENTGENOLOGY Kier, R., Herfkens, R. J., Blinder, R. A., Leight, G. S., UTZ, J. A., Silverman, P. M. 1986; 147 (3): 497-500

    Abstract

    The ability of MRI to detect parathyroid gland enlargement was assessed using 1.5-T systems and surface coil reception. Nine patients with primary hyperparathyroidism were studied before surgical neck exploration. Five-millimeter-thick axial images were obtained from the thyroid cartilage to the sternal notch. Both T1 and T2 contrast-weighted spin-echo sequences were performed in most cases. MRI correctly identified six out of seven parathyroid adenomas. In the false-negative case, T2 contrast-weighted sequences were not performed for technical reasons. In the one case of surgically proven parathyroid hyperplasia, a lesion identified by MRI as a parathyroid adenoma coincided at surgery with the largest of three hyperplastic parathyroid glands. A single case demonstrated a potential pitfall in the search for ectopic parathyroid glands: A large colloid cyst in the posterior portion of the thyroid gland showed signal characteristics indistinguishable from a parathyroid adenoma. The enlarged parathyroid glands were best visualized on T2 contrast-weighted sequences, with the lesions demonstrating greater signal than surrounding tissues.

    View details for Web of Science ID A1986D685000010

    View details for PubMedID 3488653

  • MRI OF BRAIN IRON AMERICAN JOURNAL OF ROENTGENOLOGY Drayer, B., Burger, P., Darwin, R., Riederer, S., Herfkens, R., Johnson, G. A. 1986; 147 (1): 103-110

    Abstract

    A prominently decreased signal intensity in the globus pallidum, reticular substantia nigra, red nucleus, and dentate nucleus was routinely noted in 150 consecutive individuals on T2-weighted images (SE 2000/100) using a high field strength (1.5 T)MR system. This MR finding correlated closely with the decreased estimated T2 relaxation times and the sites of preferential accumulation of ferric iron using the Perls staining method on normal postmortem brains. The decreased signal intensity on T2-weighted images thus provides an accurate in vivo map of the normal distribution of brain iron. Perls stain and MR studies in normal brain also confirm an intermediate level of iron distribution in the striatum, and still lower levels in the cerebral gray and white matter. In the white matter, iron concentration is (a) absent in the most posterior portion of the internal capsule and optic radiations, (b) higher in the frontal than occipital regions, and (c) prominent in the subcortical "U" fibers, particularly in the temporal lobe. There is no iron in the brain at birth; it increases progressively with aging. Knowledge of the distribution of brain iron should assist in elucidating normal anatomic structures and in understanding neurodegenerative, demyelinating, and cerebrovascular disorders.

    View details for Web of Science ID A1986C820100024

    View details for PubMedID 3487201

  • PARKINSON PLUS SYNDROME - DIAGNOSIS USING HIGH-FIELD MR IMAGING OF BRAIN IRON RADIOLOGY Drayer, B. P., Olanow, W., Burger, P., Johnson, G. A., Herfkens, R., Riederer, S. 1986; 159 (2): 493-498

    Abstract

    The distribution of iron in the brain was analyzed using high field strength (1.5 T) magnetic resonance (MR) imaging in 14 healthy control individuals and six patients with Parkinson plus syndromes (multisystem atrophy and progressive supranuclear palsy) who were unresponsive to antiparkinsonian therapy. The normal topographic distribution of iron in the brain as indicated by high field MR images coincided precisely with the distribution of iron in the brain as determined by Perls staining for ferric iron. In Parkinson plus syndromes, there were abnormally increased concentrations of iron (decreased T2 relaxation times) in the putamen, and less prominent increases in the caudate nucleus and lateral pars compacta of the substantia nigra. In high field strength MR images of normal patients, the decreased signal intensity in the globus pallidus is more prominent than that of the putamen. In MR images of patients with Parkinson plus syndromes, the decreased signal intensity of the putamen is more prominent than that of the globus pallidus.

    View details for Web of Science ID A1986C006700038

    View details for PubMedID 3961182

  • MAGNETIC-RESONANCE-IMAGING OF BRAIN IRON AMERICAN JOURNAL OF NEURORADIOLOGY Drayer, B., Burger, P., Darwin, R., Riederer, S., Herfkens, R., Johnson, G. A. 1986; 7 (3): 373-380
  • A VENTILATOR FOR MAGNETIC-RESONANCE-IMAGING INVESTIGATIVE RADIOLOGY Hedlund, L. W., Deitz, J., Nassar, R., Herfkens, R., Vock, P., Dahlke, J., KUBEK, R., Effmann, E. L., Putman, C. E. 1986; 21 (1): 18-23

    Abstract

    Breathing motion severely degrades the quality of magnetic resonance images (MRI) of the thorax and upper abdomen and interferes with the acquisition of quantitative data. To minimize these motion effects, we built an MRI compatible ventilator for use in animal studies. Solid state circuitry is used for controlling ventilation parameters. The ventilator can be triggered internally at frequencies of 0.1 to 30 Hz or it can be triggered externally such as by the MRI pulse sequence. When triggered by the scanner, ventilation is synchronized to occur between image data acquisitions. Thus, image data are obtained when there is no breathing motion and at a minimum lung volume when hydrogen density is maximum. Since the ventilator can be adjusted to operate at virtually any frequency from conventional to high frequency, ventilation can be synchronized to all commonly used repetition times (100 ms to 2000 ms or more; 600 to 30 breaths/min). Scan synchronous ventilation eliminates breathing motion artifacts from most imaging sequences (single and multiple spin echo and inversion recovery). Best image quality is obtained when scan synchronous ventilation is combined with cardiac gating. These methods are also useful for quantitative research studies of thoracic and abdominal organs.

    View details for Web of Science ID A1986AXU0400003

    View details for PubMedID 3455924

  • NONINVASIVE DETECTION AND MONITORING OF REGIONAL MYOCARDIAL-ISCHEMIA INSITU USING DEPTH-RESOLVED P-31 NMR-SPECTROSCOPY PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Bottomley, P. A., Herfkens, R. J., Smith, L. S., BRAZZAMANO, S., Blinder, R., Hedlund, L. W., Swain, J. L., REDINGTON, R. W. 1985; 82 (24): 8747-8751

    Abstract

    Phosphorus (31P) NMR spectra showing the relative concentrations of phosphocreatine, ATP, and Pi were recorded noninvasively from localized regions in the left ventricles of dog hearts in situ by using depth-resolved surface-coil spectroscopy at 1.5 T. Proton (1H) NMR surface-coil imaging was used to position 31P NMR coils and to determine the location of depth-resolved volumes immediately prior to 31P examination. Occlusion of the left anterior descending coronary artery produced regional ischemia detected as changes in the ratios of phosphocreatine, ATP, and Pi and by changes in the pH measured from the spectra. Spectral changes were not typically observed in regions adjacent to ischemic myocardium. Reperfusion produced some recovery, and ventricular fibrillation resulted in deterioration in high-energy metabolites. The location and size of ischemic tissue was measured by single-photon-emission computed tomography (SPECT) and gamma-ray counting or by staining excised hearts. The technique should permit the long-term noninvasive monitoring of the metabolic response of the heart to pathologic processes and allow assessment of interventions.

    View details for Web of Science ID A1985AXL4200101

    View details for PubMedID 3866249

  • Magnetic resonance imaging at high-strength magnetic fields. Magnetic resonance annual Herfkens, R. J., Johnson, G. A. 1985: 197-215

    View details for PubMedID 3917235

  • TIME COURSE AND MECHANISM OF ALTERATIONS IN PROTON RELAXATION DURING LIVER-REGENERATION IN THE RAT HEPATOLOGY Sostman, H. D., Gore, J. C., Flye, M. W., Johnson, G. A., Herfkens, R. J. 1985; 5 (4): 538-543

    Abstract

    We studied the proton T1 and T2, water and lipid content of regenerating rat liver from 1 to 7 days after 70% hepatectomy. Liver from normal and sham-operated animals and splenic tissue from all animals were studied as controls. In vivo proton spectroscopy and imaging of liver was performed in a separate group of control and posthepatectomy rats. The T2 of regenerating liver, but not of sham or normal control liver, was prolonged. Changes in T1, relative to normal tissue, were found in liver and spleen of both operated groups. Lipid content, assessed both by extraction of tissue samples and by in vivo spectroscopy, was increased in regenerating tissue but not in controls. Water content was similarly increased in regenerating liver tissue. Changes in water and lipid content appeared to contribute to the alterations in proton relaxation which we observed.

    View details for Web of Science ID A1985ANA1800002

    View details for PubMedID 2991104

  • TISSUE RELAXATION-TIME - INVIVO FIELD-DEPENDENCE RADIOLOGY Johnson, G. A., Herfkens, R. J., Brown, M. A. 1985; 156 (3): 805-810

    Abstract

    Relaxation times (T1 and T2) were measured in vivo in mongrel dogs at fields of 0.3, 0.5, 1.0, 1.35, and 1.5 tesla (T). T1 was measured using nine values of inversion time ranging from 10 to 1,280 msec. T2 was measured with a four-point multiple spin-echo sequence. Relaxation times were calculated for muscle, kidney cortex, spleen, and adipose tissue. T2 is independent of field. A linear fit to the field dependence of T1 yields slopes of 400-500 msec/T for tissues in which the primary source of protons is water. The lower slope of adipose (approximately 150 msec/T) reflects the different mechanism of spin-lattice relaxation of the -CH2 protons.

    View details for Web of Science ID A1985ANZ9200046

    View details for PubMedID 2991980

  • CARDIAC IMAGING USING GATED MAGNETIC-RESONANCE RADIOLOGY Lanzer, P., Botvinick, E. H., Schiller, N. B., Crooks, L. E., Arakawa, M., Kaufman, L., Davis, P. L., Herfkens, R., Lipton, M. J., Higgins, C. B. 1984; 150 (1): 121-127

    Abstract

    To overcome the limitations of magnetic resonance (MR) cardiac imaging using nongated data acquisition, three methods for acquiring a gating signal, which could be applied in the presence of a magnetic field, were tested: an air-filled plethysmograph, a laser-Doppler capillary perfusion flowmeter, and an electrocardiographic gating device. The gating signal was used for timing of MR imaging sequences (IS). Application of each gating method yielded significant improvements in structural MR image resolution of the beating heart, although with both plethysmography and laser-Doppler velocimetry it was difficult to obtain cardiac images from the early portion of the cardiac cycle due to an intrinsic delay between the ECG R wave and peripheral detection of the gating signal. Variations in the temporal relationship between the R wave and plethysmographic and laser-Doppler signals produced inconsistencies in the timing of IS. Since the ECG signal is virtually free of these problems, the preferable gating technique is IS synchronization with an electrocardiogram. The gated images acquired with this method provide sharp definition of internal cardiac morphology and can be temporarily referenced to end diastole and end systole or intermediate points.

    View details for Web of Science ID A1984RV27000024

    View details for PubMedID 6227934

  • MECHANISMS OF CONTRAST IN NMR IMAGING JOURNAL OF COMPUTER ASSISTED TOMOGRAPHY Wehrli, F. W., MacFall, J. R., SHUTTS, D., Breger, R., Herfkens, R. J. 1984; 8 (3): 369-380

    Abstract

    Nuclear magnetic resonance pixel intensity and contrast-to-noise has been computed and presented in graphical form for various tissues in the normal central nervous system, on the assumption that the signal intensity is proportional to the macroscopic transverse spin magnetization at the time of detection. T1, T2, and spin density values were experimentally determined using chi-square minimization techniques. Additionally, spin density was derived from partial saturation scans obtained with a long repetition time compared with the spin-lattice relaxation time. Pulse sequences discussed comprise partial saturation, saturation recovery, spin echo, and Carr- Purcell - Meiboom -Gill ( CPMG ). The complicated dependence of signal and contrast-to-noise on the pulse timing parameters and the specific pulse sequence makes it appear desirable to display image intensity so that the dependence on the extrinsic (operator-selectable parameter) is eliminated. Whereas T2 images can be derived from CPMG scans without excessive time penalty, this is not the case for T1 and spin density.

    View details for Web of Science ID A1984SR70400001

    View details for PubMedID 6725682

  • CT-DETERMINED PULMONARY-ARTERY DIAMETERS IN PREDICTING PULMONARY-HYPERTENSION INVESTIGATIVE RADIOLOGY Kuriyama, K., Gamsu, G., Stern, R. G., Cann, C. E., Herfkens, R. J., Brundage, B. H. 1984; 19 (1): 16-22

    Abstract

    This study was to determine if the diameters of pulmonary arteries measured from computed tomographic (CT) scans could be used 1) as indicators of pulmonary artery hypertension and 2) as a reliable base for calculating mean pulmonary artery pressure. The diameters of the main, left, proximal right, distal right, interlobar, and left descending pulmonary arteries were measured from CT scans in 32 patients with cardiopulmonary disease and in 26 age- and sex-matched control subjects. Diameters were measured using a special computer program that could display a CT density profile of the artery and its adjacent tissues. The upper limit of normal diameter for the main pulmonary artery was found to be 28.6 mm (mean + 2 SD). In the patient group, the diameters were correlated with data from cardiac catheterization. In these patients, a diameter of the main pulmonary artery above 28.6 mm readily predicted the presence of pulmonary hypertension. The calculated cross-sectional areas of the main and interlobar pulmonary arteries (normalized for body surface area [BAS]) were found to give the best estimates of mean pulmonary artery pressure (r = 0.89, P less than 0.001 and r = 0.66, P less than 0.001). Multiple regression analysis gave the useful equation: mean pulmonary artery pressure = -10.92 + 0.07646 X area of main pulmonary artery/BSA + 0.08084 X area of the right interlobar pulmonary artery/BSA (r = 0.93, P less than 0.0001). Because CT allows precise, noninvasive measurement of the diameter of pulmonary arteries, it can be of value in detecting pulmonary hypertension and estimating mean pulmonary artery pressure.

    View details for Web of Science ID A1984RZ89800004

    View details for PubMedID 6706516

  • Cardiovascular imaging with nuclear magnetic resonance. Cardiology clinics Higgins, C. B., Botvinick, E. H., Lanzer, P., Herfkens, R., Lipton, M. J., Crooks, L. E., Kaufman, L. 1983; 1 (3): 527-539

    Abstract

    This article provides some examples of what the previous article outlined. The sections on Image Display and Myocardial Characterization contain numerous illustrations of gating, cross-sectional images, flow signals, and ischemic injury. The possibility of metabolic imaging with NMR and quantitating blood flow is also considered.

    View details for PubMedID 6544138

  • NUCLEAR MAGNETIC-RESONANCE IMAGING OF THE INFARCTED MUSCLE - A RAT MODEL RADIOLOGY Herfkens, R. J., Sievers, R., Kaufman, L., SHELDON, P. E., ORTENDAHL, D. A., Lipton, M. J., Crooks, L. E., Higgins, C. B. 1983; 147 (3): 761-764

    Abstract

    Eleven Sprague-Dawley rats with experimentally produced infarction of the lower extremities were imaged by nuclear magnetic resonance (NMR) immediately after infarction, and 6 and 24 hours later. Contrast between the infarcted and control muscles was noted immediately and continued to increase through 24 hours. These changes corresponded to a significant increase in the water content of the infarcted extremity at 24 hours. These results suggest promise for NMR imaging in the identification of myocardial infarction and should encourage further investigation in this area.

    View details for Web of Science ID A1983QQ25100023

    View details for PubMedID 6844611

  • THE POTENTIAL IMPACT OF NUCLEAR MAGNETIC-RESONANCE IMAGING ON CARDIOVASCULAR DIAGNOSIS CIRCULATION Kaufman, L., Crooks, L., Sheldon, P., Hricak, H., Herfkens, R., Bank, W. 1983; 67 (2): 251-257

    Abstract

    Nuclear magnetic resonance (NMR) is used to generate cross-sectional images of the human body that show excellent anatomic and functional definition. The NMR imaging process involves interactions between electromagnetic fields and the hydrogen nuclei being imaged. These interactions occur on time scales of milliseconds to seconds. Consequently, the motion of these nuclei, for instance, when carried by blood, produces distinct signatures that are used to assess flow in major vessels. Myocardial dyskinesis also produces visible effects. Because of these effects, NMR imaging may be a safe and effective tool in the diagnosis and assessment of cardiovascular disease.

    View details for Web of Science ID A1983PY52000001

    View details for PubMedID 6848214

  • NUCLEAR MAGNETIC-RESONANCE IMAGING OF ATHEROSCLEROTIC DISEASE RADIOLOGY Herfkens, R. J., Higgins, C. B., Hricak, H., Lipton, M. J., Crooks, L. E., SHELDON, P. E., Kaufman, L. 1983; 148 (1): 161-166

    Abstract

    Nuclear magnetic resonance (NMR) images of 93 patients undergoing studies of the abdomen and pelvis were studied for evidence of lesions of the aorta and the iliac and femoral arteries; atherosclerotic lesions were present in 13 of them. The lesions consisted of eccentric and concentric mural thickening with luminal narrowing and discrete plaques protruding into the vessel lumen. This appearance was distinctly different from the morphology of the internal vessel surface and uniformly thin vessel wall in normal patients and volunteers under the age of 30 years. Intraluminal flow signals observed in atherosclerotic and nonatherosclerotic subjects could be distinguished from mural lesions because of their lack of contiguity with the vessel wall and variation in appearance on multiple images obtained with the first and second spin echo. This initial experience suggests a potential role for NMR in the noninvasive imaging of atherosclerotic lesions. The natural contrast between flowing blood and the vessel wall indicates a distinct advantage of NMR for vascular imaging.

    View details for Web of Science ID A1983QV03900032

    View details for PubMedID 6856827

  • COMPUTERIZED-TOMOGRAPHY IN CHRONIC THROMBOEMBOLIC PULMONARY-HYPERTENSION AMERICAN HEART JOURNAL Kereiakes, D. J., Herfkens, R. J., Brundage, B. H., Gamsu, G., Lipton, M. J. 1983; 106 (6): 1432-1436

    View details for Web of Science ID A1983RT79700023

    View details for PubMedID 6650368

  • EVALUATION OF THE POST-CORONARY ARTERY BYPASS PATIENT BY MYOCARDIAL PERFUSION SCINTIGRAPHY AND COMPUTED-TOMOGRAPHY AMERICAN JOURNAL OF ROENTGENOLOGY ENGELSTAD, B. L., Wagner, S., Herfkens, R., Botvinick, E., BRUNDAGE, B., Lipton, M. 1983; 141 (3): 507-512

    Abstract

    The clinical utility of 201Tl scintigraphy and of computed tomography for the noninvasive assessment of graft patency and regional myocardial perfusion was evaluated in 24 patients who had undergone aortocoronary bypass surgery. Perfusion defects on 201Tl scintigraphy (reversible or new, fixed) correlated (100% sensitivity, 78% specificity) with occlusion or stenosis of a graft or significant new native vessel disease. Graft occlusion was accurately demonstrated by dynamic computed tomography (100% sensitivity, 96% specificity) but did not uniformly correlate with regional perfusion. Perfusion defects in the distribution of patent grafts resulted from progressive native vessel disease or graft stenosis without complete occlusion. The absence of exercise-induced perfusion defects in regions of occluded grafts was attributed to suboptimal exercise, collateralization, or noncritical native vessel stenosis. The two studies provide complementary anatomic and physiologic information in the evaluation of the postbypass patient.

    View details for Web of Science ID A1983RD45500014

    View details for PubMedID 6603759

  • NUCLEAR MAGNETIC-RESONANCE IMAGING OF ACUTE MYOCARDIAL-INFARCTION IN DOGS - ALTERATIONS IN MAGNETIC-RELAXATION TIMES AMERICAN JOURNAL OF CARDIOLOGY Higgins, C. B., Herfkens, R., Lipton, M. J., Sievers, R., Sheldon, P., Kaufman, L., Crooks, L. E. 1983; 52 (1): 184-188

    Abstract

    Nuclear magnetic resonance (NMR) imaging was used to study 24-hour-old acute myocardial infarctions in 8 dogs. Images and measurements of excised hearts were obtained in a 6.5 ml bore-resistive NMR imager (0.35 Tesla). Spin echo NMR imaging in each instance demonstrated the area of infarction as a region of increased signal intensity compared with that in normal myocardium. The T1 and T2 values of the area of infarction were greater than those of normal myocardium in all dogs. For each dog the T1 value was greater for the infarct region; however, the group mean value for T1 (ms) of the infarct region (728 +/- 94) was not significantly greater than that for the normal region (650 +/- 87). The T2 value (ms) was discriminate for all dogs, and the mean value for the infarct region (48 +/- 2) was significantly different (p less than 0.01) from the value for normal myocardium (42 +/- 1). The percent water content of the infarct (79 +/- 1%) was significantly greater (p less than 0.01) than that of normal regions (76 +/- 1%). The linear relationship between T2 value and percent water content showed a good correlation coefficient (r = 0.90; p less than 0.01). NMR imaging detects acute myocardial infarction as a positive image without contrast media. Increased signal intensity of the infarct is related to increased hydrogen density and increased T2 relaxation time.

    View details for Web of Science ID A1983QX24200036

    View details for PubMedID 6858909

  • NUCLEAR MAGNETIC-RESONANCE IMAGING OF THE CARDIOVASCULAR-SYSTEM - NORMAL AND PATHOLOGIC FINDINGS RADIOLOGY Herfkens, R. J., Higgins, C. B., Hricak, H., Lipton, M. J., Crooks, L. E., Lanzer, P., Botvinick, E., BRUNDAGE, B., SHELDON, P. E., Kaufman, L. 1983; 147 (3): 749-759

    Abstract

    Whole body nuclear magnetic resonance (NMR) imaging of the cardiovascular system was carried out in early clinical trials in 244 volunteers and patients using a 3.5 KGauss (0.35 T) unit. The spin echo technique with multiple imaging parameters was used. Blood vessels were clearly discriminated from solid organs and lesions because little or no intraluminal signal is seen with laminar blood flow at normal velocities, whereas a more intense image is generated by solid organs. Characteristic flow signals were observed in normal patients and were accentuated by varying the imaging parameters. Cardiac chambers were well delineated in some patients on nongated images. In one case, internal topography of the ventricles was exquisitely displayed on a gated image. Intraluminal pathology, such as dissection of the aorta, aneurysms of the aorta and left ventricle, and aortic atheroma, was clearly demonstrated. Patency of coronary arterial bypass grafts was shown. Abnormal flow patterns due to slow or turbulent flow were accentuated on images using the second spin echo. This preliminary experience indicates the considerable potential of NMR imaging in the evaluation of cardiovascular diseases.

    View details for Web of Science ID A1983QQ25100022

    View details for PubMedID 6601813

  • NON-INVASIVE DETECTION OF PROXIMAL PULMONARY-ARTERY THROMBOSIS BY TWO-DIMENSIONAL ECHOCARDIOGRAPHY AND COMPUTERIZED-TOMOGRAPHY AMERICAN HEART JOURNAL Dicarlo, L. A., Schiller, N. B., HERFKENS, R. L., Brundage, B. H., Lipton, M. J. 1982; 104 (4): 879-881

    View details for Web of Science ID A1982PK88900030

    View details for PubMedID 7124605

  • THE PHASE IMAGE - ITS RELATIONSHIP TO PATTERNS OF CONTRACTION AND CONDUCTION CIRCULATION Botvinick, E., Dunn, R., FRAIS, M., OCONNELL, W., SHOSA, D., Herfkens, R., Scheinman, M. 1982; 65 (3): 551-560

    Abstract

    To determine the relationship of phase changes and abnormalities of ventricular contraction and conduction, we performed phase image analysis of blood pool scintigrams in 29 patients. Eleven patients had no evidence of blood pool contraction or ECG conduction abnormalities, four had contraction abnormalities, seven had abnormal conduction and seven had abnormalities of both variables. The phase delay generally related to the degree of contraction abnormality. The mean phase delay in hypokinetic segments differed from that in normokinetic segments in the same patient (p less than 0.025), the phase delay of akinetic and dyskinetic segments differed from that in normokinetic segments (p less than 0.001) and the phase delay in dyskinetic segments differed from that in akinetic segments (p less than 0.005), but there was a significant overlap in the phase delay in normal and hypokinetic segments. Also, in patients with conduction abnormalities, the minimal associated regional phase delay presented a phase dispersion and a pattern of contraction consistent with the pattern of conduction and different from normal. A single study performed both at rest and with stress demonstrated the effect of heart rate on phase assessment and confirmed the independent effects of contraction and conduction on phase delay. Acquisition and analytic methods should add significantly to the resolution of the phase method.

    View details for Web of Science ID A1982NC40100021

    View details for PubMedID 7055877

  • RESOLUTION AND CONTRAST RECOVERY AT DEPTH IN PLANAR NUCLEAR IMAGES PHYSICS IN MEDICINE AND BIOLOGY ORTENDAHL, D. A., SHOSA, D. W., Kaufman, L., Hattner, R., Herfkens, R., ROWAN, W. 1982; 27 (2): 257-275

    Abstract

    Resolution and contrast recovery in planar nuclear images at depth with a high purity germanium (HPGe) camera has been achieved through use of a weighted back projection (WBP) method. The algorithm can be derived from Bayes' theorem using the point spread function of the camera. The variations in the formulation of WBP (one single pass and two iterative procedures) are presented with the characteristics and performance of each method. The evaluation procedure determines the behaviour of signal-to-noise ratio, contrast and texture after application of the algorithm. Both real and simulated cold lesions obtained with the HPGe camera are studied with sizes ranging from 3 mm to 17 mm and background count densities from 100 to 6400 counts cm2. Application of WBP is shown to increase spatial resolution and contrast without a concomitant reduction in signal-to-noise ratio. Images obtained with the HPGe camera and processed with WBP are presented. The algorithm has been applied to the scintillation camera, yielding significant resolution and contrast recovery despite the presence of scatter and textured noise present in the HPGe images.

    View details for Web of Science ID A1982NC95000007

    View details for PubMedID 6280214

  • MEASUREMENT OF CARDIAC-OUTPUT BY COMPUTED TRANSMISSION TOMOGRAPHY INVESTIGATIVE RADIOLOGY Herfkens, R. J., Axel, L., Lipton, M. J., Napel, S., BERNINGER, W., REDINGTON, R. 1982; 17 (6): 550-553

    Abstract

    The capability of computed tomography (CT) scanning to measure cardiac output was explored using ten anesthetized dogs, and the results were compared with those obtained by thermodilution. Dynamic CT scans were performed at the level of the aortic root while small peripheral intravenous boluses of contrast medium were injected. Time/density curves were generated using a gamma variate fitting program. These were used to estimate cardiac output by applying indicator dilution principles. CT results correlated favorably (r = 0.86) with those of thermodilution. This feasibility study indicates the utility of CT for obtaining physiologic measurements of cardiac function and should encourage further studies to develop the potential of CT for cardiovascular diagnostic purposes.

    View details for Web of Science ID A1982PS51300005

    View details for PubMedID 7152858

  • DETECTION OF INTRAVENTRICULAR THROMBI BY COMPUTED-TOMOGRAPHY RADIOLOGY Godwin, J. D., Herfkens, R. J., SKIOLDEBRAND, C. G., Brundage, B. H., Schiller, N. B., Lipton, M. J. 1981; 138 (3): 717-721

    Abstract

    Intraventricular thrombosis (usually occurring after myocardial infarction) can lead to embolization, with serious consequences. Angiocardiography and two-dimensional echocardiography both are limited in their ability to detect intraventricular thrombi. Computed tomography (CT) with intravenous administration of contrast material gave excellent definition of intraventricular thrombi in three patients with recent myocardial infarctions and in one patient with a pericardial patch of the right ventricular apex. A ventricular mural thrombus was detected in a dog after an experimentally induced myocardial infarction. CT offers some advantages over contrast ventriculography and echocardiography in detecting intraventricular thrombosis.

    View details for Web of Science ID A1981LE80900030

    View details for PubMedID 7465852

  • COMPUTED-TOMOGRAPHY FOR FOLLOW-UP OF CHRONIC AORTIC DISSECTIONS RADIOLOGY Godwin, J. D., Turley, K., Herfkens, R. J., Lipton, M. J. 1981; 139 (3): 655-660

    Abstract

    Patients who have chronic dissections of the aorta are prone to re-dissection, extension of dissection, aortic aneurysm, and aortic rupture. Computed tomography (CT) with contrast enhancement provides a convenient, noninvasive method for follow-up of these patients. We used CT in a group of twelve patients who were treated for aortic dissection. CT demonstrated re-dissection, aneurysmal dilation of the aorta, and delayed filling of the false lumen. CT also showed persistent patency of the false lumen in almost all of the postoperative cases.

    View details for Web of Science ID A1981LS03200018

    View details for PubMedID 7232732

  • NUCLEAR MAGNETIC-RESONANCE (NMR) IMAGING AT THE UNIVERSITY OF CALIFORNIA, SAN-FRANCISCO PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS Crooks, L. E., Herfkens, R., Davis, P. L. 1981; 273: 11-15
  • EVALUATION OF COARCTATION OF THE AORTA BY COMPUTED-TOMOGRAPHY JOURNAL OF COMPUTER ASSISTED TOMOGRAPHY Godwin, J. D., Herfkens, R. J., Brundage, B. H., Lipton, M. J. 1981; 5 (2): 153-156

    Abstract

    We used computed tomography (CT) after contrast medium administration to evaluate three adult patients with coarctation of the aorta. In preoperative scans, CT showed the aortic narrowing and deformity and the poststenotic dilation associated with coarctation. In postoperative examinations, CT was used to check for residual or recurrent narrowing and for the development of complications such as aneurysm or dissection. Since CT is noninvasive, it can be performed as an outpatient procedure. Its potential applications and its limitations with respect to aortography are discussed.

    View details for Web of Science ID A1981LF71000001

    View details for PubMedID 7217436

  • Nuclear magnetic resonance imaging. Progress in nuclear medicine Crooks, L., Herfkens, R., Kaufman, L., HOENNINGER, J., Arakawa, M., McRee, R., Watts, J. 1981; 7: 149-163

    Abstract

    NMR imaging is based on the ability to induce and monitor resonance of the magnetic moment of nuclei with an odd number of protons and/or neutrons in the presence of magnetic fields. By the use of magnetic fields whose strength varies with position, it is possible to define both the location and concentration of resonant nuclei, and, thereby, to create images that reflect their distribution in tissue. Hydrogen because it is the most sensitive of the stable nuclei to NMR and because it is also the most abundant nucleus in the body, is ideally suited for NMR imaging.

    View details for PubMedID 7323305

  • NUCLEAR MAGNETIC-RESONANCE IMAGING OF THE ABNORMAL LIVE RAT AND CORRELATIONS WITH TISSUE CHARACTERISTICS RADIOLOGY Herfkens, R., Davis, P., Crooks, L., Kaufman, L., Price, D., Miller, T., Margulis, A. R., Watts, J., HOENNINGER, J., Arakawa, M., McRee, R. 1981; 141 (1): 211-218

    Abstract

    Nuclear magnetic resonance (NMR) images of live rats with sterile and pyogenic abscesses, hematomas, and various implanted and spontaneous neoplasms demonstrated good contrast differentiation between pathologic and surrounding normal tissues. This differentiation was maximal when both the T1 and T2 tissue relaxation times were used as criteria. Neoplasms have a broad range of T1 and T2 values and may be confused with abscesses or hematomas. Tissue rate constants (1/T1 and 1/T2) are mainly dependent on total water content, the exception being fat, which has a 1/T2 value much shorter than that expected on the basis of water content alone.

    View details for Web of Science ID A1981MJ49400036

    View details for PubMedID 7197379

  • TECHNICAL ASPECTS AND CLINICAL-APPLICATIONS OF CT-X, A DYNAMIC CT SCANNER JOURNAL OF COMPUTER ASSISTED TOMOGRAPHY BERNINGER, W., REDINGTON, R., LEUE, W., Axel, L., Norman, D., BRUNDAGE, B., Carlsson, E., Herfkens, R., Lipton, M. 1981; 5 (2): 206-215

    Abstract

    CT/X is an X-ray computed tomographic scanner system designed for research in the clinical applications of rapid sequence scanning. The minimum scan time is 1.5 sec, and up to 18 images of the same cross section can be derived from scans taken over a 30 sec time interval. With this high image rate, the transit of a bolus of iodinated contrast medium can be followed through any cross section of the body. Rapid sequence scanning through a series of contiguous levels can also be performed, and 12 levels can be scanned in less than 50 sec. The short aggregate scan period minimizes the likelihood of interslice patient motion resulting in high quality multiplanar images. To fully exploit this capability, an imaging facility capable of reformatting axial transverse display data into a plane of arbitrary orientation has been incorporated into the system. A computer-electrocardiographic interface is also provided for use in retrospective cardiac gating. The capabilities of the scanner are illustrated with selective clinical studies.

    View details for Web of Science ID A1981LF71000012

    View details for PubMedID 7217447

  • EVALUATION OF DISSECTIONS AND ANEURYSMS OF THE THORACIC AORTA BY CONVENTIONAL AND DYNAMIC CT SCANNING RADIOLOGY Godwin, J. D., HERFKENS, R. L., SKIOLDEBRAND, C. G., Federle, M. P., Lipton, M. J. 1980; 136 (1): 125-133

    Abstract

    Conventional computed tomography (CT) with intravenous contrast injection effectively demonstrates the features of aneurysms of the thoracic aorta (dilatation, calcification, intraluminal thrombus, and displacement and erosion of adjacent structures). In aortic dissection, CT can establish the diagnosis by demonstrating (a) double channels with an intimal flap or (b) displaced intimal calcifications if one channel is thrombosed. Dynamic CT following a contrast bolus shows the relative rate of filling of the true and false channels and demonstrates the intimal flap with optimum clarity. Reformatted CT images (paraxial and oblique) display the entire thoracic aorta in the plane of the arch, resembling an aortogram. CT is noninvasive and can be easily repeated to assess progress. Although aortography is still required prior to surgery in some cases, CT is a safe screening procedure that may avoid some invasive angiographic procedures.

    View details for Web of Science ID A1980JY14700025

    View details for PubMedID 7384486

  • INVIVO IMAGING OF THE RAT ANATOMY WITH NUCLEAR MAGNETIC-RESONANCE RADIOLOGY Hansen, G., Crooks, L. E., Davis, P., DeGroot, J., Herfkens, R., Margulis, A. R., Gooding, C., Kaufman, L., HOENNINGER, J., Arakawa, M., McRee, R., Watts, J. 1980; 136 (3): 695-700

    Abstract

    Live rats were imaged by nuclear magnetic resonance (NMR). These images demonstrated fine detail and high object contrast. Motion artifacts are not apparent in 4-minute images, and major blood vessels are demonstrated as regions of low signal intensity because of blood flow. Selective contrast enhancement is possible by varying NMR imager accumulation parameters.

    View details for Web of Science ID A1980KF35400020

    View details for PubMedID 7403549

  • HIGH-RESOLUTION EMISSION COMPUTED-TOMOGRAPHY WITH A SMALL GERMANIUM CAMERA IEEE TRANSACTIONS ON NUCLEAR SCIENCE ORTENDAHL, D. A., Kaufman, L., ROWAN, W., Herfkens, R., Price, D. C. 1980; 27 (1): 459-462
  • DETECTION OF PATENT CORONARY-BYPASS GRAFTS BY COMPUTED-TOMOGRAPHY - A PRELIMINARY-REPORT CIRCULATION Brundage, B. H., Lipton, M. J., Herfkens, R. J., BERNINGER, W. H., REDINGTON, R. W., Chatterjee, K., Carlsson, E. 1980; 61 (4): 826-831

    Abstract

    Twenty-three coronary bypass graft patients were evaluated by a contrast-enhanced computed tomography (CT) technique to determine graft patency. Four to six 4.8-second sequenced scans with a 1-second interscan interval were obtained in each patient during the hand injection of 25-30 ml of contrast medium in a peripheral vein. Patency of grafts was determined by a characteristic contrast enhancement. The CT technique correlated with angiographic assessment of graft patency in 59 of 62 grafts (95%). We conclude that this relatively noninvasive technique shows promise as a method for determining coronary bypass graft patency.

    View details for Web of Science ID A1980JL68900023

    View details for PubMedID 6965619

  • CONTRAST MEDIUM-ENHANCED COMPUTED-TOMOGRAPHY FOR EVALUATING ISCHEMIC HEART-DISEASE CARDIOVASCULAR MEDICINE Lipton, M. J., Brundage, B. H., DOHERTY, P. W., Herfkens, R., BERNINGER, W. H., REDINGTON, R. W., Chatterjee, K., Carlsson, E. 1979; 4 (12): 1219-?

Conference Proceedings


  • Measurement of vessel wall strain using cine phase contrast MRI Wedding, K. L., Draney, M. T., Herfkens, R. J., Zarins, C. K., Taylor, C. A., Pelc, N. J. JOHN WILEY & SONS INC. 2002: 418-428

    Abstract

    To determine the feasibility of using magnetic resonance imaging (MRI) to non-invasively measure strain in the aortic wall.Cine phase contrast MRI was used to measure the velocity of the aortic wall and calculate changes in circumferential strain over the cardiac cycle. A deformable vessel phantom was used for initial testing and in vitro validation. Ultrasonic sonomicrometer crystals were attached to the vessel wall and used as a gold standard.In the in vitro validation, MRI-calculated wall displacements were within 0.02 mm of the sonomicrometer measurements when maximal displacement was 0.28 mm. The measured maximum strain in vitro was 0.02. The in vivo results were on the same order as prior results using ultrasound echo-tracking.Results of in vivo studies and measurement of cyclic strain in human thoracic and abdominal aortas demonstrate the feasibility of the technique.

    View details for DOI 10.1002/jmri.10077

    View details for Web of Science ID 000174759700008

    View details for PubMedID 11948831

  • Freehand iMRI-guided large-gauge core needle biopsy: A new minimally invasive technique for diagnosis of enhancing breast lesions Daniel, B. L., Birdwell, R. L., Butts, K., Nowels, K. W., Ikeda, D. M., Heiss, S. G., Cooper, C. R., Jeffrey, S. S., Dirbas, F. M., Herfkens, R. J. JOHN WILEY & SONS INC. 2001: 896-902

    Abstract

    The lack of reliable methods for minimally invasive biopsy of suspicious enhancing breast lesions has hindered the utilization of contrast-enhanced magnetic resonance imaging (MRI) for the detection and diagnosis of breast cancer. In this study, a freehand method was developed for large-gauge core needle biopsy (LCNB) guided by intraprocedural MRI (iMRI). Twenty-seven lesions in nineteen patients were biopsied using iMRI-guided LCNB without significant complications. Diagnostic tissue was obtained in all cases. Nineteen of the 27 lesions were subsequently surgically excised. Histopathologic analysis confirmed that iMRI-guided LCNB correctly distinguished benign lesions from malignancy in 18 of the 19 lesions. The histology revealed by core biopsy was partially discrepant with surgical biopsy in 2 of the other 19 lesions. Freehand iMRI-guided LCNB of enhancing breast lesions is promising. Larger studies are needed to determine the smallest lesion that can be sampled reliably and to precisely measure the accuracy of iMRI-guided LCNB as a minimally invasive tool to diagnose suspicious lesions found by breast MRI. J. Magn. Reson. Imaging 2001;13:896-902.

    View details for Web of Science ID 000171296500013

    View details for PubMedID 11382950

  • Transplantation of adult-sized kidneys into infants induces major blood flow changes Salvatierra, O., Singh, T., Shifrin, R., Conley, S., Alexander, S., Tanney, D., Lemley, K., Sarwal, M., Mackle, F., Alfrey, E., Orlandi, P., Zarins, C., Herfkens, R. ELSEVIER SCIENCE INC. 1999: 236-237

    View details for Web of Science ID 000078960600099

    View details for PubMedID 10083090

  • VASCULAR MAGNETIC-RESONANCE-IMAGING Herfkens, R. J. ASSOC UNIV RADIOLOGISTS. 1995: S131-S132

    View details for Web of Science ID A1995RT15800021

    View details for PubMedID 9419724

  • ULTRAFAST CONTRAST-ENHANCED MAGNETIC-RESONANCE-IMAGING OF CONGENITAL HYDRONEPHROSIS IN A RAT MODEL Fichtner, J., Spielman, D., Herfkens, R., BOINEAU, F. G., Lewy, J. E., Shortliffe, L. M. WILLIAMS & WILKINS. 1994: 682-687

    Abstract

    Since new ultrafast magnetic resonance imaging (MRI) might offer unique advantages for evaluating renal blood flow, anatomy and urinary excretion, we used this technique to characterize a rat model with congenital partial ureteropelvic junction obstruction. MRI of 9 rats from an inbred colony with unilateral congenital (nonsurgical) hydronephrosis was compared with the contralateral nonhydronephrotic kidney serving as control. Our new imaging technique consisted of a 1-minute ultrafast gradient recalled imaging sequence during the first minute (64 images per imaging time 960 milliseconds) after contrast bolus injection with gadolinium-diethylenetriaminepentaacetic acid for assessment of renal blood flow followed by a 30-minute period with image acquisition every 30 seconds to study contrast distribution and excretion. Signal intensities were analyzed continuously over selected, different regions of interest. Anatomic analysis of MRI noncontrast studies showed precise delineation of the hydronephrotic pelvis and corticomedullary junction. After contrast gadolinium-diethylenetriaminepentaacetic acid injection signal intensity from the region of interest from hydronephrotic kidneys differed from nonhydronephrotic kidneys by showing less cortical decrease, suggesting decreased blood flow, less medullary decrease and delayed contrast excretion. Clear contrast distribution among the cortex, medulla and collecting system allowed selective estimation of different regions of interest and excellent anatomic evaluation. Renal anatomy and renal pelvic pressures were confirmed after scans were completed. Ultrafast contrast enhanced MRI allows simultaneous assessment of renal morphology, blood flow and function. In hydronephrotic partially obstructed kidneys distinct flow and excretion patterns measured with contrast enhanced MRI allow differentiation between the obstructed and nonobstructed kidney on physiological rather than purely anatomic means. This imaging technique may provide a useful method of evaluating congenital hydronephrosis obviating the need for multiple different diagnostic procedures.

    View details for Web of Science ID A1994NW33000024

    View details for PubMedID 8021995

  • Magnetic resonance. Ehman, R. L., ANDERSON, M. W., Crues, J. V., Herfkens, R. J., Hricak, H., Lenkinski, R. E., Lomas, D. J., Mitchell, D. G., Riederer, S. J., Ross, J. R. 1994: 938-944

    View details for PubMedID 8115660

  • QUANTITATIVE DIFFERENTIAL PULMONARY PERFUSION - MR-IMAGING VERSUS RADIONUCLIDE LUNG-SCANNING Silverman, J. M., JULIEN, P. J., Herfkens, R. J., Pelc, N. J. RADIOLOGICAL SOC NORTH AMERICA. 1993: 699-701

    Abstract

    To compare the results of quantitative analysis of differential pulmonary artery blood flow performed with phase-contrast cine magnetic resonance (MR) images with those of differential radionuclide pulmonary perfusion scanning in preoperative lung transplantation patients.Forty preoperative lung transplantation patients underwent prospective, quantitative analysis of differential pulmonary artery blood flow performed with MR imaging and radionuclide pulmonary perfusion scanning. MR imaging analysis was performed at 1.5 T with a phase-contrast cine pulse sequence to acquire data perpendicular to each central pulmonary artery.Comparative analysis of differential pulmonary perfusion showed excellent correlation between the two modalities in all patients (P = .0001). MR imaging enabled calculation of the pulmonary artery blood flow to each lung; radionuclide lung scanning enabled only calculation of relative perfusion to each lung.MR imaging is as effective as radionuclide lung scanning in assessment of relative, and superior for determination of absolute differential, pulmonary perfusion.

    View details for Web of Science ID A1993MH58600014

    View details for PubMedID 8234693

  • DYNAMIC BREATH-HOLD MULTIPLANAR SPOILED GRADIENT-RECALLED MR-IMAGING WITH GADOLINIUM ENHANCEMENT FOR DIFFERENTIATING HEPATIC HEMANGIOMAS FROM MALIGNANCIES AT 1.5-T Whitney, W. S., Herfkens, R. J., Jeffrey, R. B., McDonnell, C. H., Li, K. C., VANDALSEM, W. J., Low, R. N., Francis, I. R., DABATIN, J. F., Glazer, G. M. RADIOLOGICAL SOC NORTH AMERICA. 1993: 863-870

    Abstract

    To compare the enhancement patterns of focal liver lesions at dynamic breath-hold gadolinium-enhanced multiplanar spoiled gradient-recalled (SPGR) magnetic resonance (MR) imaging with T2 relaxation times in the differentiation of liver hemangiomas from malignancies.Forty-seven patients with focal liver lesions underwent MR imaging with spin-echo and gadolinium-enhanced multiplanar SPGR techniques. T2 relaxation times and enhancement patterns were compared for accuracy in liver lesion characterization.Enhancement patterns allowed better characterization of liver lesions than did T2 relaxation times. Only specific patterns of contrast enhancement indicated a hemangioma. Although 18 of the 33 malignancies and 10 of the 12 hemangiomas showed progressive centripetal hyperintense enhancement, only hemangiomas filled in with hyperintense peripheral nodules. Malignancies often filled in with hyperintense thick rinds.Gadolinium-enhanced multiplanar SPGR imaging allows more accurate characterization of liver lesions than does T2 relaxation time.

    View details for Web of Science ID A1993MH58600042

    View details for PubMedID 8234717

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