Bio

Clinical Focus


  • Diagnostic Radiology

Academic Appointments


Administrative Appointments


  • Director of Clinical Trials, Stanford Radiology (2017 - Present)
  • Director of Body CT, Stanford Radiology (2017 - Present)

Professional Education


  • Fellowship:Stanford University Radiology Fellowships (2013) CA
  • Residency:University of Alabama at Birmingham Radiology Residency (2012) AL
  • Internship:Brigham and Women's Hospital General Surgery Residency (2008) MA
  • MBA, UCLA Anderson School of Management (2015)
  • Fellowship, Stanford Body Imaging (2013)
  • Board Certification: Diagnostic Radiology, American Board of Radiology (2012)
  • Medical Education:University of Alabama School of Medicine (2007) AL

Research & Scholarship

Current Research and Scholarly Interests


Advanced CT, MRI, & Ultrasound Techniques & Applications
Dual-energy CT
Machine Learning
Artificial Intelligence & Deep Learning

Publications

All Publications


  • Reproducibility of CT Radiomic Features within the Same Patient: Influence of Radiation Dose and CT Reconstruction Settings. Radiology Meyer, M., Ronald, J., Vernuccio, F., Nelson, R. C., Ramirez-Giraldo, J. C., Solomon, J., Patel, B. N., Samei, E., Marin, D. 2019: 190928

    Abstract

    Background Results of recent phantom studies show that variation in CT acquisition parameters and reconstruction techniques may make radiomic features largely nonreproduceable and of limited use for prognostic clinical studies. Purpose To investigate the effect of CT radiation dose and reconstruction settings on the reproducibility of radiomic features, as well as to identify correction factors for mitigating these sources of variability. Materials and Methods This was a secondary analysis of a prospective study of metastatic liver lesions in patients who underwent staging with single-energy dual-source contrast material-enhanced staging CT between September 2011 and April 2012. Technique parameters were altered, resulting in 28 CT data sets per patient that included different dose levels, section thicknesses, kernels, and reconstruction algorithm settings. By using a training data set (n = 76), reproducible intensity, shape, and texture radiomic features (reproducibility threshold, R2 ≥ 0.95) were selected and correction factors were calculated by using a linear model to convert each radiomic feature to its estimated value in a reference technique. By using a test data set (n = 75), the reproducibility of hierarchical clustering based on 106 radiomic features measured with different CT techniques was assessed. Results Data in 78 patients (mean age, 60 years ± 10; 33 women) with 151 liver lesions were included. The percentage of radiomic features deemed reproducible for any variation of the different technical parameters was 11% (12 of 106). Of all technical parameters, reconstructed section thickness had the largest impact on the reproducibility of radiomic features (12.3% [13 of 106]) if only one technical parameter was changed while all other technical parameters were kept constant. The results of the hierarchical cluster analysis showed improved clustering reproducibility when reproducible radiomic features with dedicated correction factors were used (rho = 0.39-0.71 vs rho = 0.14-0.47). Conclusion Most radiomic features are highly affected by CT acquisition and reconstruction settings, to the point of being nonreproducible. Selecting reproducible radiomic features along with study-specific correction factors offers improved clustering reproducibility. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Sosna in this issue.

    View details for DOI 10.1148/radiol.2019190928

    View details for PubMedID 31573400

  • Assessing the Effectiveness of a Health Care Economics Curriculum for Radiology Residents JOURNAL OF THE AMERICAN COLLEGE OF RADIOLOGY Dixon, A., Johnson, K., Strickland, L., Patel, B., Said, N. 2019; 16 (8): 1083–87
  • Comparison of Iodine Quantification and Conventional Attenuation Measurements for Differentiating Small, Truly Enhancing Renal Masses From High-Attenuation Nonenhancing Renal Lesions With Dual-Energy CT AMERICAN JOURNAL OF ROENTGENOLOGY Meyer, M., Nelson, R. C., Vernuccio, F., Gonzalez, F., Schabel, C., Mileto, A., Patel, B. N., Schoenberg, S. O., Marin, D. 2019; 213 (1): W26–W36

    Abstract

    The purpose of this study is to determine whether iodine quantification techniques from contrast-enhanced dual-energy CT (DECT) data allow equal differentiation of small enhancing renal masses from high-attenuation (> 20 HU of unenhanced attenuation) nonenhancing lesions, compared with conventional attenuation measurements.A total of 220 nonconsecutive patients (mean [± SD] age, 66 ± 13 years; 130 men and 90 women) with 265 high-attenuation renal lesions (mean attenuation, 54 ± 33 HU; 91 enhancing lesions) were included. Each patient underwent single-energy unenhanced CT followed by DECT during the nephrographic phase using one of four different high-end DECT platforms (first- and second-generation rapid-kilovoltage-switching DECT platforms and second- and third-generation dual-source DECT platforms). Iodine quantification measurements and conventional attenuation change measurements were calculated for each lesion. Diagnostic accuracy was determined by pathologic analysis, confirmation with another imaging modality, or greater than 24 months of imaging follow-up as the reference standard.The diagnostic accuracy for differentiating enhancing from nonenhancing renal lesions was significantly higher for conventional attenuation change measurements, compared with iodine quantification measurements (AUC values, 0.973 vs 0.875; p < 0.0001). The diagnostic performance of iodine quantification measurements improved only marginally with the utilization of DECT platform-specific optimized iodine quantification thresholds, yielding AUC values of 0.907 and 0.893 for the rapid-kilovoltage-switching DECT and dual-source DECT platforms, respectively. Unenhanced lesion attenuation (p = 0.0010) and intraparenchymal location (p = 0.0249) significantly influenced the diagnostic accuracy of the iodine quantification techniques.Iodine quantification from DECT data yields inferior diagnostic accuracy when compared with conventional attenuation change measurements for differentiating small, truly enhancing renal masses and high-attenuation renal lesions.

    View details for DOI 10.2214/AJR.18.20547

    View details for Web of Science ID 000472493900004

    View details for PubMedID 30917024

  • Virtual Unenhanced Images at Dual-Energy CT: Influence on Renal Lesion Characterization RADIOLOGY Meyer, M., Nelson, R. C., Vernuccio, F., Gonzalez, F., Farjat, A. E., Patel, B. N., Samei, E., Henzler, T., Schoenberg, S. O., Marin, D. 2019; 291 (2): 380–89
  • Systematic Review and Meta-Analysis Investigating the Diagnostic Yield of Dual-Energy CT for Renal Mass Assessment AMERICAN JOURNAL OF ROENTGENOLOGY Bellini, D., Panvini, N., Laghi, A., Marin, D., Patel, B. N., Wang, C. L., Carbone, I., Mileto, A. 2019; 212 (5): 1044–53
  • Virtual Unenhanced Images at Dual-Energy CT: Influence on Renal Lesion Characterization. Radiology Meyer, M., Nelson, R. C., Vernuccio, F., Gonzalez, F., Farjat, A. E., Patel, B. N., Samei, E., Henzler, T., Schoenberg, S. O., Marin, D. 2019: 181100

    Abstract

    Background Dual-energy (DE) CT allows reconstruction of virtual noncontrast (VNC) images from a single-phase contrast agent-enhanced examination, potentially reducing the need for multiphasic CT to characterize renal lesions. However, data regarding diagnostic performance of VNC images for the characterization of renal lesions are limited. Purpose To determine whether renal mass CT performed by using VNC images allows for reliable identification of renal lesions and differentiation of contrast-enhanced from unenhanced lesions, compared with unenhanced images. Materials and Methods This is a retrospective study of 293 patients (105 women [mean age, 65 years; age range, 18-91 years] and 188 men [mean age, 66 years; age range, 23-90 years] with 379 renal lesions [craniocaudal diameter, 1.0-4.0 cm]) who underwent a single-energy unenhanced CT examination followed by a nephrographic-phase DE CT between June 2013 and October 2017 by using one of four different DE CT platforms from two vendors. VNC images were calculated by using vendor-specific algorithms. Each lesion was classified in a blinded and independent fashion by using the VNC or unenhanced image in combination with the nephrographic images. Attenuation measurements were obtained on the VNC, unenhanced, and nephrographic images. Unenhanced images and pathologic or imaging follow-up for more than 24 months served as reference standard. Results There was strong overall agreement between VNC and unenhanced images for renal lesion characterization (Cramer V = 0.85). VNC images yielded a high diagnostic performance (area under the receiver operating characteristic curve, 0.91; 95% confidence interval: 0.86, 0.95) for facilitation of differentiation of contrast-enhanced from unenhanced renal lesions. However, there was a reduction in diagnostic performance for depicting contrast-enhanced renal lesions by using VNC compared with unenhanced images (area under the receiver operating characteristic curve, 0.91 [95% confidence interval: 0.86, 0.95] vs 0.96 [95% confidence interval: 0.93, 0.99]; P < .001). Mean absolute difference between the VNC and unenhanced attenuation was 9.2 HU ± 8.7. Conclusion Virtual noncontrast images enabled accurate renal lesion characterization, albeit with a reduction in diagnostic performance for contrast-enhanced lesion characterization. © RSNA, 2019 Online supplemental material is available for this article.

    View details for PubMedID 30860450

  • Systematic Review and Meta-Analysis Investigating the Diagnostic Yield of Dual-Energy CT for Renal Mass Assessment. AJR. American journal of roentgenology Bellini, D., Panvini, N., Laghi, A., Marin, D., Patel, B. N., Wang, C. L., Carbone, I., Mileto, A. 2019: 1–10

    Abstract

    OBJECTIVE: The objective of our study was to perform a systematic review and meta-analysis to evaluate the diagnostic accuracy of dual-energy CT (DECT) for renal mass evaluation.MATERIALS AND METHODS: In March 2018, we searched MEDLINE, Cochrane Database of Systematic Reviews, Embase, and Web of Science databases. Analytic methods were based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Pooled estimates for sensitivity, specificity, and diagnostic odds ratios were calculated for DECT-based virtual monochromatic imaging (VMI) and iodine quantification techniques as well as for conventional attenuation measurements from renal mass CT protocols. I2 was used to evaluate heterogeneity. The methodologic quality of the included studies and potential bias were assessed using items from the Quality Assessment Tool for Diagnostic Accuracy Studies 2 (QUADAS-2).RESULTS: Of the 1043 articles initially identified, 13 were selected for inclusion (969 patients, 1193 renal masses). Cumulative data of sensitivity, specificity, and summary diagnostic odds ratio for VMI were 87% (95% CI, 80-92%; I2, 92.0%), 93% (95% CI, 90-96%; I2, 18.0%), and 183.4 (95% CI, 30.7-1093.4; I2, 61.6%), respectively. Cumulative data of sensitivity, specificity, and summary diagnostic odds ratio for iodine quantification were 99% (95% CI, 97-100%; I2, 17.6%), 91% (95% CI, 89-94%; I2, 84.2%), and 511.5 (95% CI, 217-1201; I2, 0%). No significant differences in AUCs were found when comparing iodine quantification to conventional attenuation measurements (p = 0.79).CONCLUSION: DECT yields high accuracy for renal mass evaluation. Determination of iodine content with the iodine quantification technique shows diagnostic accuracy similar to conventional attenuation measurements from renal mass CT protocols. The iodine quantification technique may be used to characterize incidental renal masses when a dedicated renal mass protocol is not available.

    View details for PubMedID 30835518

  • Assessing the Effectiveness of a Health Care Economics Curriculum for Radiology Residents. Journal of the American College of Radiology : JACR Dixon, A., Johnson, K., Strickland, L., Patel, B., Said, N. 2019

    View details for PubMedID 30819453

  • Dual-Energy CT Material Density Iodine Quantification for Distinguishing Vascular From Nonvascular Renal Lesions: Normalization Reduces Intermanufacturer Threshold Variability. AJR. American journal of roentgenology Patel, B. N., Vernuccio, F., Meyer, M., Godwin, B., Rosenberg, M., Rudnick, N., Harring, S., Nelson, R., Ramirez-Giraldo, J. C., Farjat, A., Marin, D. 2019; 212 (2): 366–76

    Abstract

    OBJECTIVE: The purpose of this study was to determine whether a single, uniform normalized iodine threshold reduces variability and enables reliable differentiation between vascular and nonvascular renal lesions independent of the dual-energy CT (DECT) platform used.MATERIALS AND METHODS: In this retrospective, HIPAA-compliant, institutional review board-approved study, 247 patients (156 men, 91 women; mean age ± SD, 67 ± 12 years old) with 263 renal lesions (193 nonvascular, 70 vascular) underwent unenhanced single-energy and contrast-enhanced DECT scans. One hundred and six nonvascular and 38 vascular lesions were scanned on two dual-source DECT (dsDECT) scanners, and 87 nonvascular and 32 vascular lesions were scanned on two rapid-kilovoltage-switching single-source DECT (rsDECT) scanners. Optimal absolute and normalized (to aorta) lesion iodine thresholds were determined for each platform type and for the entire cohort combined.RESULTS: Mean optimal absolute discriminant thresholds were 1.3 mg I/mL (95% CI, 1.2-1.9 mg I/mL), 1.6 mg I/mL (95% CI, 0.9-1.5 mg I/mL), and 1.5 mg I/mL (95% CI, 1.4-1.7 mg I/mL) for dsDECT, rsDECT, and combined cohorts, respectively. Optimal normalized discriminant thresholds were 0.3 mg I/mL (95% CI, 0.2-0.4 mg I/mL) for both the dsDECT and rsDECT cohorts, and 0.3 mg I/mL (0.3-0.4 mg I/mL) for the combined cohort. The AUC, sensitivity, and specificity for the combined optimal normalized discriminant threshold of 0.3 mg I/mL was 0.96 (95% CI, 0.92-1.00), 0.93 (0.84-0.97), and 0.95 (0.91-0.98), respectively. Normalization resulted in decreased variability and better lesion separation (effect size, 1.77 vs 1.69, p < 0.0001).CONCLUSION: The optimal absolute discriminant threshold for evaluating renal lesions varies depending on the type of DECT platform, though this difference is not statistically significant. Variation can be reduced with a better separation of vascular and nonvascular lesions by normalizing iodine quantification to the aorta.

    View details for PubMedID 30667306

  • ACR Appropriateness Criteria® Acute Onset of Scrotal Pain-Without Trauma, Without Antecedent Mass. Journal of the American College of Radiology : JACR Wang, C. L., Aryal, B., Oto, A., Allen, B. C., Akin, O., Alexander, L. F., Bardo, D. M., Chong, J., Froemming, A. T., Fulgham, P. F., Heller, M. T., Maranchie, J. K., Mody, R. N., Patel, B. N., Schieda, N., Turkbey, I. B., Venkatesan, A. M., Yoo, D. C., Lockhart, M. E. 2019; 16 (5S): S38–S43

    Abstract

    An acute scrotum is defined as testicular swelling with acute pain and can reflect multiple etiologies including epididymitis or epididymo-orchitis, torsion of the spermatic cord, or torsion of the testicular appendages. Quick and accurate diagnosis of acute scrotum and its etiology with imaging is necessary because a delayed diagnosis of torsion for as little as 6 hours can cause irreparable testicular damage. Ultrasound duplex Doppler of the scrotum is usually appropriate as the initial imaging for the acute onset of scrotal pain without trauma or antecedent mass in an adult or child. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

    View details for PubMedID 31054757

  • CheXpert: A Large Chest Radiograph Dataset with Uncertainty Labels and Expert Comparison Irvin, J., Rajpurkar, P., Ko, M., Yu, Y., Ciurea-Ilcus, S., Chute, C., Marklund, H., Haghgoo, B., Ball, R., Shpanskaya, K., Seekins, J., Mong, D. A., Halabi, S. S., Sandberg, J. K., Jones, R., Larson, D. B., Langlotz, C. P., Patel, B. N., Lungren, M. P., Ng, A. Y., AAAI ASSOC ADVANCEMENT ARTIFICIAL INTELLIGENCE. 2019: 590–97
  • Groove pancreatitis: a clinical and imaging overview. Abdominal radiology (New York) Patel, B. N., Brooke Jeffrey, R., Olcott, E. W., Zaheer, A. 2019

    Abstract

    Groove or paraduodenal pancreatitis is an uncommon fibroinflammatory form of pancreatitis involving the anatomic space of the pancreatic groove located between the C-loop of the duodenum and the head of the pancreas. Although in some patients there are distinctive clinical and imaging features of groove pancreatitis (GP), there is often significant overlap with other infiltrative processes involving the pancreatic groove such as pancreatic ductal adenocarcinoma or duodenal carcinoma. In this review, we summarize the most distinctive clinical and imaging aspects of GP and highlight some important distinguishing features that may aid in differentiating malignant lesions involving the pancreatic groove.

    View details for DOI 10.1007/s00261-019-02239-1

    View details for PubMedID 31559471

  • Deep Learning-Assisted Diagnosis of Cerebral Aneurysms Using the HeadXNet Model. JAMA network open Park, A., Chute, C., Rajpurkar, P., Lou, J., Ball, R. L., Shpanskaya, K., Jabarkheel, R., Kim, L. H., McKenna, E., Tseng, J., Ni, J., Wishah, F., Wittber, F., Hong, D. S., Wilson, T. J., Halabi, S., Basu, S., Patel, B. N., Lungren, M. P., Ng, A. Y., Yeom, K. W. 2019; 2 (6): e195600

    Abstract

    Deep learning has the potential to augment clinician performance in medical imaging interpretation and reduce time to diagnosis through automated segmentation. Few studies to date have explored this topic.To develop and apply a neural network segmentation model (the HeadXNet model) capable of generating precise voxel-by-voxel predictions of intracranial aneurysms on head computed tomographic angiography (CTA) imaging to augment clinicians' intracranial aneurysm diagnostic performance.In this diagnostic study, a 3-dimensional convolutional neural network architecture was developed using a training set of 611 head CTA examinations to generate aneurysm segmentations. Segmentation outputs from this support model on a test set of 115 examinations were provided to clinicians. Between August 13, 2018, and October 4, 2018, 8 clinicians diagnosed the presence of aneurysm on the test set, both with and without model augmentation, in a crossover design using randomized order and a 14-day washout period. Head and neck examinations performed between January 3, 2003, and May 31, 2017, at a single academic medical center were used to train, validate, and test the model. Examinations positive for aneurysm had at least 1 clinically significant, nonruptured intracranial aneurysm. Examinations with hemorrhage, ruptured aneurysm, posttraumatic or infectious pseudoaneurysm, arteriovenous malformation, surgical clips, coils, catheters, or other surgical hardware were excluded. All other CTA examinations were considered controls.Sensitivity, specificity, accuracy, time, and interrater agreement were measured. Metrics for clinician performance with and without model augmentation were compared.The data set contained 818 examinations from 662 unique patients with 328 CTA examinations (40.1%) containing at least 1 intracranial aneurysm and 490 examinations (59.9%) without intracranial aneurysms. The 8 clinicians reading the test set ranged in experience from 2 to 12 years. Augmenting clinicians with artificial intelligence-produced segmentation predictions resulted in clinicians achieving statistically significant improvements in sensitivity, accuracy, and interrater agreement when compared with no augmentation. The clinicians' mean sensitivity increased by 0.059 (95% CI, 0.028-0.091; adjusted P = .01), mean accuracy increased by 0.038 (95% CI, 0.014-0.062; adjusted P = .02), and mean interrater agreement (Fleiss κ) increased by 0.060, from 0.799 to 0.859 (adjusted P = .05). There was no statistically significant change in mean specificity (0.016; 95% CI, -0.010 to 0.041; adjusted P = .16) and time to diagnosis (5.71 seconds; 95% CI, 7.22-18.63 seconds; adjusted P = .19).The deep learning model developed successfully detected clinically significant intracranial aneurysms on CTA. This suggests that integration of an artificial intelligence-assisted diagnostic model may augment clinician performance with dependable and accurate predictions and thereby optimize patient care.

    View details for DOI 10.1001/jamanetworkopen.2019.5600

    View details for PubMedID 31173130

  • Association of Interim FDG-PET Imaging During Chemoradiation for Squamous Anal Canal Carcinoma With Recurrence INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS Hong, J. C., Cui, Y., Patel, B. N., Rushing, C. N., Faught, A. M., Eng, J. S., Higgins, K., Yin, F., Das, S., Czito, B. G., Willett, C. G., Palta, M. 2018; 102 (4): 1046–51

    Abstract

    Imaging parameters from 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) before and after chemoradiation therapy (CRT) for anal canal cancer correlate with clinical outcomes. This prospective, hypothesis-generating pilot study investigates the relationship between interim PET imaging during CRT for anal canal cancer and clinical outcome.From June 2012 to August 2015, 30 patients with anal canal cancer were enrolled in a prospective clinical study of PET prior to and during CRT after ∼30 Gy. PET parameters of the primary site included maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG). MTV and TLG were calculated based on 40% SUVmax (MTV40, TLG40) or SUV 2.5 (MTV2.5, TLG2.5) thresholds for pretreatment and interim images. Absolute and change in PET parameters were assessed for association with freedom from local and regional recurrence (FFLR) using single-predictor Cox regression models. Local and regional recurrence were primary and nodal (in-field) recurrences, respectively.Twenty-three patients were eligible for analysis. Patients were excluded with nonsquamous cell histology, recurrent anal cancer, and incomplete studies due to treatment toxicity or patient choice. Median follow-up was 2.5 years. Pretreatment MTV40 (HR 1.4 [95% CI 1.02-2.05]), interim MTV2.5 (1.4 [1.04-1.89]), and interim TLG2.5 (1.1 [1.01-1.21]) were associated with FFLR.In this prospective pilot study, interim PET parameters were associated with FFLR. These results warrant further investigation assessing the value of interim PET as a biomarker of response in the treatment of patients with anal cancer.

    View details for PubMedID 29891206

  • Deep-learning-assisted diagnosis for knee magnetic resonance imaging: Development and retrospective validation of MRNet. PLoS medicine Bien, N., Rajpurkar, P., Ball, R. L., Irvin, J., Park, A., Jones, E., Bereket, M., Patel, B. N., Yeom, K. W., Shpanskaya, K., Halabi, S., Zucker, E., Fanton, G., Amanatullah, D. F., Beaulieu, C. F., Riley, G. M., Stewart, R. J., Blankenberg, F. G., Larson, D. B., Jones, R. H., Langlotz, C. P., Ng, A. Y., Lungren, M. P. 2018; 15 (11): e1002699

    Abstract

    BACKGROUND: Magnetic resonance imaging (MRI) of the knee is the preferred method for diagnosing knee injuries. However, interpretation of knee MRI is time-intensive and subject to diagnostic error and variability. An automated system for interpreting knee MRI could prioritize high-risk patients and assist clinicians in making diagnoses. Deep learning methods, in being able to automatically learn layers of features, are well suited for modeling the complex relationships between medical images and their interpretations. In this study we developed a deep learning model for detecting general abnormalities and specific diagnoses (anterior cruciate ligament [ACL] tears and meniscal tears) on knee MRI exams. We then measured the effect of providing the model's predictions to clinical experts during interpretation.METHODS AND FINDINGS: Our dataset consisted of 1,370 knee MRI exams performed at Stanford University Medical Center between January 1, 2001, and December 31, 2012 (mean age 38.0 years; 569 [41.5%] female patients). The majority vote of 3 musculoskeletal radiologists established reference standard labels on an internal validation set of 120 exams. We developed MRNet, a convolutional neural network for classifying MRI series and combined predictions from 3 series per exam using logistic regression. In detecting abnormalities, ACL tears, and meniscal tears, this model achieved area under the receiver operating characteristic curve (AUC) values of 0.937 (95% CI 0.895, 0.980), 0.965 (95% CI 0.938, 0.993), and 0.847 (95% CI 0.780, 0.914), respectively, on the internal validation set. We also obtained a public dataset of 917 exams with sagittal T1-weighted series and labels for ACL injury from Clinical Hospital Centre Rijeka, Croatia. On the external validation set of 183 exams, the MRNet trained on Stanford sagittal T2-weighted series achieved an AUC of 0.824 (95% CI 0.757, 0.892) in the detection of ACL injuries with no additional training, while an MRNet trained on the rest of the external data achieved an AUC of 0.911 (95% CI 0.864, 0.958). We additionally measured the specificity, sensitivity, and accuracy of 9 clinical experts (7 board-certified general radiologists and 2 orthopedic surgeons) on the internal validation set both with and without model assistance. Using a 2-sided Pearson's chi-squared test with adjustment for multiple comparisons, we found no significant differences between the performance of the model and that of unassisted general radiologists in detecting abnormalities. General radiologists achieved significantly higher sensitivity in detecting ACL tears (p-value = 0.002; q-value = 0.019) and significantly higher specificity in detecting meniscal tears (p-value = 0.003; q-value = 0.019). Using a 1-tailed t test on the change in performance metrics, we found that providing model predictions significantly increased clinical experts' specificity in identifying ACL tears (p-value < 0.001; q-value = 0.006). The primary limitations of our study include lack of surgical ground truth and the small size of the panel of clinical experts.CONCLUSIONS: Our deep learning model can rapidly generate accurate clinical pathology classifications of knee MRI exams from both internal and external datasets. Moreover, our results support the assertion that deep learning models can improve the performance of clinical experts during medical imaging interpretation. Further research is needed to validate the model prospectively and to determine its utility in the clinical setting.

    View details for PubMedID 30481176

  • Deep learning for chest radiograph diagnosis: A retrospective comparison of the CheXNeXt algorithm to practicing radiologists. PLoS medicine Rajpurkar, P., Irvin, J., Ball, R. L., Zhu, K., Yang, B., Mehta, H., Duan, T., Ding, D., Bagul, A., Langlotz, C. P., Patel, B. N., Yeom, K. W., Shpanskaya, K., Blankenberg, F. G., Seekins, J., Amrhein, T. J., Mong, D. A., Halabi, S. S., Zucker, E. J., Ng, A. Y., Lungren, M. P. 2018; 15 (11): e1002686

    Abstract

    BACKGROUND: Chest radiograph interpretation is critical for the detection of thoracic diseases, including tuberculosis and lung cancer, which affect millions of people worldwide each year. This time-consuming task typically requires expert radiologists to read the images, leading to fatigue-based diagnostic error and lack of diagnostic expertise in areas of the world where radiologists are not available. Recently, deep learning approaches have been able to achieve expert-level performance in medical image interpretation tasks, powered by large network architectures and fueled by the emergence of large labeled datasets. The purpose of this study is to investigate the performance of a deep learning algorithm on the detection of pathologies in chest radiographs compared with practicing radiologists.METHODS AND FINDINGS: We developed CheXNeXt, a convolutional neural network to concurrently detect the presence of 14 different pathologies, including pneumonia, pleural effusion, pulmonary masses, and nodules in frontal-view chest radiographs. CheXNeXt was trained and internally validated on the ChestX-ray8 dataset, with a held-out validation set consisting of 420 images, sampled to contain at least 50 cases of each of the original pathology labels. On this validation set, the majority vote of a panel of 3 board-certified cardiothoracic specialist radiologists served as reference standard. We compared CheXNeXt's discriminative performance on the validation set to the performance of 9 radiologists using the area under the receiver operating characteristic curve (AUC). The radiologists included 6 board-certified radiologists (average experience 12 years, range 4-28 years) and 3 senior radiology residents, from 3 academic institutions. We found that CheXNeXt achieved radiologist-level performance on 11 pathologies and did not achieve radiologist-level performance on 3 pathologies. The radiologists achieved statistically significantly higher AUC performance on cardiomegaly, emphysema, and hiatal hernia, with AUCs of 0.888 (95% confidence interval [CI] 0.863-0.910), 0.911 (95% CI 0.866-0.947), and 0.985 (95% CI 0.974-0.991), respectively, whereas CheXNeXt's AUCs were 0.831 (95% CI 0.790-0.870), 0.704 (95% CI 0.567-0.833), and 0.851 (95% CI 0.785-0.909), respectively. CheXNeXt performed better than radiologists in detecting atelectasis, with an AUC of 0.862 (95% CI 0.825-0.895), statistically significantly higher than radiologists' AUC of 0.808 (95% CI 0.777-0.838); there were no statistically significant differences in AUCs for the other 10 pathologies. The average time to interpret the 420 images in the validation set was substantially longer for the radiologists (240 minutes) than for CheXNeXt (1.5 minutes). The main limitations of our study are that neither CheXNeXt nor the radiologists were permitted to use patient history or review prior examinations and that evaluation was limited to a dataset from a single institution.CONCLUSIONS: In this study, we developed and validated a deep learning algorithm that classified clinically important abnormalities in chest radiographs at a performance level comparable to practicing radiologists. Once tested prospectively in clinical settings, the algorithm could have the potential to expand patient access to chest radiograph diagnostics.

    View details for PubMedID 30457988

  • Abdominal Radiography With Digital Tomosynthesis: An Alternative to Computed Tomography for Identification of Urinary Calculi? UROLOGY Wollin, D. A., Gupta, R. T., Young, B., Cone, E., Kaplan, A., Marin, D., Patel, B. N., Mazurowski, M. A., Scales, C. D., Ferrandino, M. N., Preminger, G. M., Lipkin, M. E. 2018; 120: 56–61

    Abstract

    To compare the accuracy of plain abdominal radiography (kidneys, ureter, and bladder [KUB]) with digital tomosynthesis (DT) to noncontrast computed tomography (NCCT), the gold standard imaging modality for urinary stones. Due to radiation and cost concerns, KUB is often used for diagnosis and follow-up of nephrolithiasis. DT, a novel technique that produces high-quality radiographs with less radiation and/or cost than low-dose NCCT, has not been assessed in this situation.Seven fresh tissue cadavers were implanted with stones of known size and/or composition and imaged with KUB, DT, and NCCT. Four blinded readers (2 urologists, 2 radiologists) evaluated KUBs for presence and/or location of calculi. They then re-evaluated with addition of tomograms to assess additional value. After a memory extinction period, readers evaluated NCCT images. Accuracy of detection was determined using nearest-neighbor match with generalized linear mixed modeling.Total of 59 stones were identified on reference read. Overall, NCCT and DT were both superior to KUB alone (P < .001) while the difference between DT and NCCT was not significant (P = .06). When evaluating uric acid stones, NCCT and DT outperformed KUB (P < .01 and P < .05, respectively) while DT and NCCT were similar (P = .16). Intrarenal stones were better evaluated on DT and NCCT (P < .001 compared to KUB), while DT and NCCT were similar (P = 1.00). Accuracy was lower than anticipated across modalities due to use of the cadaver model.Our study demonstrates DT is superior to KUB for identification of intrarenal calculi and could replace routine use of KUB or NCCT for detecting renal stones, even those composed of uric acid.

    View details for PubMedID 30006268

  • Routine MR Imaging for Pancreas MAGNETIC RESONANCE IMAGING CLINICS OF NORTH AMERICA Patel, B. N. 2018; 26 (3): 315-+
  • Characterization of Small Incidental Indeterminate Hypoattenuating Hepatic Lesions: Added Value of Single-Phase Contrast-Enhanced Dual-Energy CT Material Attenuation Analysis. AJR. American journal of roentgenology Patel, B. N., Rosenberg, M., Vernuccio, F., Ramirez-Giraldo, J. C., Nelson, R., Farjat, A., Marin, D. 2018: 1–9

    Abstract

    OBJECTIVE: The objective of this study is to determine whether single-phase contrast-enhanced dual-energy CT (DECT) material attenuation analysis improves the characterization of small (< 2.0 cm) incidental indeterminate hypoattenuating hepatic lesions, compared with conventional single-energy CT evaluation.MATERIALS AND METHODS: This retrospective study involved 55 patients (24 men and 31 women; mean [± SD] age, 63.9 ± 15.3 years) with 77 incidental hypoattenuating hepatic lesions (59 benign and 18 malignant lesions) measuring 0.5-2.0 cm who underwent single-phase contrast-enhanced DECT of the abdomen for pain. For each lesion, attenuation measurements were obtained using blended 120-kVp-equivalent images and contrast map images. DECT material attenuation images were used for iodine quantification. Optimal lesion attenuation and iodine concentration threshold values that best distinguished benign lesions from malignant lesions were generated using smooth bootstrapping. The diagnostic accuracy of the optimized thresholds was compared using the Wilcox rank sum test.RESULTS: The optimal mean (± standard error) attenuation threshold values that best differentiated benign and malignant lesions were 50.2 ± 5.2 HU and 11.5 ± 2.0 HU when blended 120-kVp and contrast map images, respectively, were used. The iodine concentration (expressed as milligrams of iodine per milliliter) differed significantly (p < 0.0001) between benign lesions (0.6 ± 0.4 mg/mL) and malignant lesions (1.7 ± 0.4 mg/mL). The optimal iodine concentration that best distinguished between benign and malignant lesions was 1.2 ± 0.1 mg I/mL. The sensitivity, specificity, and AUC value were highest for iodine concentration (0.94, 0.93, and 0.97, respectively), compared with blended images (0.89, 0.70, and 0.81, respectively) and contrast map images (0.94, 0.64, 0.77, respectively).CONCLUSION: Iodine quantification performed using single-phase contrast-enhanced DECT material attenuation images improves the characterization of small (< 2 cm) incidental indeterminate hypoattenuating hepatic lesions, compared with conventional attenuation measurements.

    View details for PubMedID 30040464

  • Strategies to Improve Image Quality on Dual-Energy Computed Tomography. Radiologic clinics of North America Patel, B. N., Marin, D. 2018; 56 (4): 641–47

    Abstract

    Dual-energy computed tomography (DECT) offers several advantages over conventional single-energy CT. These advantages include improved image quality, beam hardening correction, and metal artifact reduction. Additionally, DECT allows derivation of quantitative information through material decomposition analysis. Although newer third-generation rapid-kilovolt switching and dual-source DECT scanners have significantly improved in image quality and workflow compared with initial iterations and early scanners, sources of potential image quality degradation can exist secondary to the inherent capabilities in which the image acquisition occurs.

    View details for PubMedID 29936952

  • Energy-Specific Optimization of Attenuation Thresholds for Low-Energy Virtual Monoenergetic Images in Renal Lesion Evaluation AMERICAN JOURNAL OF ROENTGENOLOGY Patel, B. N., Farjat, A., Schabel, C., Duvnjak, P., Mileto, A., Ramirez-Giraldo, J., Marin, D. 2018; 210 (5): W205–W217

    Abstract

    The purpose of this study was to determine in vitro and in vivo the optimal threshold for renal lesion vascularity at low-energy (40-60 keV) virtual monoenergetic imaging.A rod simulating unenhanced renal parenchymal attenuation (35 HU) was fitted with a syringe containing water. Three iodinated solutions (0.38, 0.57, and 0.76 mg I/mL) were inserted into another rod that simulated enhanced renal parenchyma (180 HU). Rods were inserted into cylindric phantoms of three different body sizes and scanned with single- and dual-energy MDCT. In addition, 102 patients (32 men, 70 women; mean age, 66.8 ± 12.9 [SD] years) with 112 renal lesions (67 nonvascular, 45 vascular) measuring 1.1-8.9 cm underwent single-energy unenhanced and contrast-enhanced dual-energy CT. Optimal threshold attenuation values that differentiated vascular from nonvascular lesions at 40-60 keV were determined.Mean optimal threshold values were 30.2 ± 3.6 (standard error), 20.9 ± 1.3, and 16.1 ± 1.0 HU in the phantom, and 35.9 ± 3.6, 25.4 ± 1.8, and 17.8 ± 1.8 HU in the patients at 40, 50, and 60 keV. Sensitivity and specificity for the thresholds did not change significantly between low-energy and 70-keV virtual monoenergetic imaging (sensitivity, 87-98%; specificity, 90-91%). The AUC from 40 to 70 keV was 0.96 (95% CI, 0.93-0.99) to 0.98 (95% CI, 0.95-1.00).Low-energy virtual monoenergetic imaging at energy-specific optimized attenuation thresholds can be used for reliable characterization of renal lesions.

    View details for PubMedID 29547057

  • Extrapancreatic perineural invasion in pancreatic adenocarcinoma ABDOMINAL RADIOLOGY Patel, B. N., Olcott, E., Jeffrey, R. 2018; 43 (2): 323–31

    Abstract

    Pancreatic ductal adenocarcinoma continues to be a highly lethal disease, despite advances in modern medicine. Curative surgical options continue to carry significant morbidity and offer little improvement in overall 5-year survival. Currently, imaging plays an essential role in the pre-operative evaluation of patients who are undergoing evaluation for resection. However, some pancreatic cancers have particularly aggressive biology, despite appearing resectable by conventional imaging criteria. Imaging biomarkers that serve as surrogates for tumors with such aggressive phenotype have been recently described, namely duodenal invasion and extrapancreatic perineural invasion. In this pictorial review, we will summarize key concepts of extrapancreatic perineural invasion, describe its association with a poor prognosis, and highlight the role of imaging in its detection.

    View details for PubMedID 28980054

  • Routine MR Imaging for Pancreas. Magnetic resonance imaging clinics of North America Patel, B. N. 2018; 26 (3): 315–22

    Abstract

    MR imaging of the pancreas is a valuable tool in evaluating pancreatic disorders. It is used in conjunction with other modalities (ie, computed tomography or ultrasound), especially for problem-solving, or as a primary first-line modality for certain pancreaticobiliary indications. Because of the recent advances, many sequences can be performed rapidly, using a single breath hold. Magnetic resonance cholangiopancreatography images allow complete diagnostic assessment of the pancreatic duct without the invasiveness of an endoscopic retrograde pancreatography. This article reviews the routine MR imaging protocol for evaluating the pancreas, highlighting advantages and disadvantages in assessing pancreatic disorders.

    View details for PubMedID 30376972

  • The effects of a transjugular intrahepatic portosystemic shunt on the diagnosis of hepatocellular cancer. PloS one Wong, K., Ozeki, K., Kwong, A., Patel, B. N., Kwo, P. 2018; 13 (12): e0208233

    Abstract

    BACKGROUND AND AIMS: Transjugular intrahepatic portosystemic shunt (TIPS) may be placed to treat complications of portal hypertension by creating a conduit between the hepatic and portal vein. The diagnosis of hepatocellular carcinoma (HCC) is typically made by multiphasic imaging studies demonstrating arterial enhancement with washout on arterial, portal venous, and delayed phase imaging. The aim of our study was to determine how the presence of TIPS would affect the imaging diagnosis of HCC.METHODS: This was a single-center electronic database review of all patients who underwent multiphasic imaging with MRI or CT scan for HCC screening between January 2000 and July 2017 and who were subsequently diagnosed with HCC. Data collected included patient demographics, liver disease characteristics including CPT score, MELD-Na, AFP, type of imaging, tumor stage, and lab values at the time of HCC diagnosis. The diagnosis of HCC was made using LI-RADS criteria on contrast-enhanced CT or MR imaging and confirmed by chart abstraction as documented by the treating clinician. Demographic and imaging characteristics for HCC patients with and without TIPS were compared.RESULTS: A total of 279 patients met eligibility criteria for the study, 37 (13.2%) of whom had TIPS placed prior to diagnosis of HCC. There was no significant difference in demographics or liver disease characteristics between patients with and without TIPS. Compared to cirrhotic patients with no TIPS prior to HCC diagnosis, patients with TIPS had significantly more scans with a longer duration of surveillance until HCC diagnosis. However, LI-RADS criteria and stage of HCC at diagnosis were not significantly different between both groups. There were no differences in outcomes including liver transplant and survival.CONCLUSION: The presence of TIPS does not lead to a delayed diagnosis of HCC. It is associated, however, with greater duration of time from first scan to diagnosis of HCC.

    View details for PubMedID 30592722

  • Dual-Energy Computed Tomography Applications in Neurointervention. Journal of computer assisted tomography Wolman, D. N., Patel, B. P., Wintermark, M., Heit, J. J. 2018

    Abstract

    Dual-energy computed tomography (CT) combines the high spatial resolution of standard CT with the ability to improve contrast resolution, reduce artifact, and separate materials of different atomic weights and energy-based attenuation through postprocessing. We review the underlying physical principles and applications of dual-energy CT within the context of patients undergoing preprocedural and postprocedural evaluation for neurointerventional therapies. The broad imaging categories of cerebral ischemia and hemorrhage, head and neck angiography, and the spine are reviewed.

    View details for PubMedID 30052616

  • Financial Forecasting and Stochastic Modeling: Predicting the Impact of Business Decisions. Radiology Rubin, G. D., Patel, B. N. 2017; 283 (2): 342-358

    Abstract

    In health care organizations, effective investment of precious resources is critical to assure that the organization delivers high-quality and sustainable patient care within a supportive environment for patients, their families, and the health care providers. This holds true for organizations independent of size, from small practices to large health systems. For radiologists whose role is to oversee the delivery of imaging services and the interpretation, communication, and curation of imaging-informed information, business decisions influence where and how they practice, the tools available for image acquisition and interpretation, and ultimately their professional satisfaction. With so much at stake, physicians must understand and embrace the methods necessary to develop and interpret robust financial analyses so they effectively participate in and better understand decision making. This review discusses the financial drivers upon which health care organizations base investment decisions and the central role that stochastic financial modeling should play in support of strategically aligned capital investments. Given a health care industry that has been slow to embrace advanced financial analytics, a fundamental message of this review is that the skills and analytical tools are readily attainable and well worth the effort to implement in the interest of informed decision making. (©) RSNA, 2017 Online supplemental material is available for this article.

    View details for DOI 10.1148/radiol.2017161800

    View details for PubMedID 28418824

  • Characterization of Small Focal Renal Lesions: Diagnostic Accuracy with Single-Phase Contrast-enhanced Dual-Energy CT with Material Attenuation Analysis Compared with Conventional Attenuation Measurements. Radiology Marin, D., Davis, D., Roy Choudhury, K., Patel, B., Gupta, R. T., Mileto, A., Nelson, R. C. 2017: 161872-?

    Abstract

    Purpose To determine whether single-phase contrast material-enhanced dual-energy material attenuation analysis improves the characterization of small (1-4 cm) renal lesions compared with conventional attenuation measurements by using histopathologic analysis and follow-up imaging as the clinical reference standards. Materials and Methods In this retrospective, HIPAA-compliant, institutional review board-approved study, 136 consecutive patients (95 men and 41 women; mean age, 54 years) with 144 renal lesions (111 benign, 33 malignant) measuring 1-4 cm underwent single-energy unenhanced and contrast-enhanced dual-energy computed tomography (CT) of the abdomen. For each renal lesion, attenuation measurements were obtained; attenuation change of greater than or equal to 15 HU was considered evidence of enhancement. Dual-energy attenuation measurements were also obtained by using iodine-water, water-iodine, calcium-water, and water-calcium material basis pairs. Mean lesion attenuation values and material densities were compared between benign and malignant renal lesions by using the two-sample t test. Diagnostic accuracy of attenuation measurements and dual-energy material densities was assessed and validated by using 10-fold cross-validation to limit the effect of optimistic bias. Results By using cross-validated optimal thresholds at 100% sensitivity, iodine-water material attenuation images significantly improved specificity for differentiating between benign and malignant renal lesions compared with conventional enhancement measurements (93% [103 of 111]; 95% confidence interval: 86%, 97%; vs 81% [90 of 111]; 95% confidence interval: 73%, 88%) (P = .02). Sensitivity with iodine-water and calcium-water material attenuation images was also higher than that with conventional enhancement measurements, although the difference was not statistically significant. Conclusion Contrast-enhanced dual-energy CT with material attenuation analysis improves specificity for characterization of small (1-4 cm) renal lesions compared with conventional attenuation measurements. (©) RSNA, 2017 Online supplemental material is available for this article.

    View details for DOI 10.1148/radiol.2017161872

    View details for PubMedID 28353408

  • Dual-energy CT workflow: multi-institutional consensus on standardization of abdominopelvic MDCT protocols. Abdominal radiology Patel, B. N., Alexander, L., Allen, B., Berland, L., Borhani, A., Mileto, A., Moreno, C., Morgan, D., Sahani, D., Shuman, W., Tamm, E., Tublin, M., Yeh, B., Marin, D. 2017; 42 (3): 676-687

    Abstract

    To standardize workflow for dual-energy computed tomography (DECT) involving common abdominopelvic exam protocols.9 institutions (4 rsDECT, 1 dsDECT, 4 both) with 32 participants [average # years (range) in practice and DECT experience, 12.3 (1-35) and 4.6 (1-14), respectively] filled out a single survey (n = 9). A five-point agreement scale (0, 1, 2, 3, 4-contra-, not, mildly, moderately, strongly indicated, respectively) and utilization scale (0-not performing and shouldn't; 1-performing but not clinically useful; 2-performing but not sure if clinically useful; 3-not performing it but would like to; 4-performing and clinically useful) were used. Consensus was considered with a score of ≥2.5. Survey results were discussed over three separate live webinar sessions.5/9 (56%) institutions exclude large patients from DECT. 2 (40%) use weight, 2 (40%) use transverse dimension, and 1 (20%) uses both. 7/9 (78%) use 50 keV for low and 70 keV for medium monochromatic reconstructed images. DECT is indicated for dual liver [agreement score (AS) 3.78; utilization score (US) 3.22] and dual pancreas in the arterial phase (AS 3.78; US 3.11), mesenteric ischemia/gastrointestinal bleeding in both the arterial and venous phases (AS 2.89; US 2.79), RCC exams in the arterial phase (AS 3.33; US 2.78), and CT urography in the nephrographic phase (AS 3.11; US 2.89). DECT for renal stone and certain single-phase exams is indicated (AS 3.00).DECT is indicated during the arterial phase for multiphasic abdominal exams, nephrographic phase for CTU, and for certain single-phase and renal stone exams.

    View details for DOI 10.1007/s00261-016-0966-6

    View details for PubMedID 27888303

  • Effect of Radiation Dose Reduction and Reconstruction Algorithm on Image Noise, Contrast, Resolution, and Detectability of Subtle Hypoattenuating Liver Lesions at Multidetector CT: Filtered Back Projection versus a Commercial Model-based Iterative Reconstruction Algorithm. Radiology Solomon, J., Marin, D., Roy Choudhury, K., Patel, B., Samei, E. 2017: 161736-?

    Abstract

    Purpose To determine the effect of radiation dose and iterative reconstruction (IR) on noise, contrast, resolution, and observer-based detectability of subtle hypoattenuating liver lesions and to estimate the dose reduction potential of the IR algorithm in question. Materials and Methods This prospective, single-center, HIPAA-compliant study was approved by the institutional review board. A dual-source computed tomography (CT) system was used to reconstruct CT projection data from 21 patients into six radiation dose levels (12.5%, 25%, 37.5%, 50%, 75%, and 100%) on the basis of two CT acquisitions. A series of virtual liver lesions (five per patient, 105 total, lesion-to-liver prereconstruction contrast of -15 HU, 12-mm diameter) were inserted into the raw CT projection data and images were reconstructed with filtered back projection (FBP) (B31f kernel) and sinogram-affirmed IR (SAFIRE) (I31f-5 kernel). Image noise (pixel standard deviation), lesion contrast (after reconstruction), lesion boundary sharpness (average normalized gradient at lesion boundary), and contrast-to-noise ratio (CNR) were compared. Next, a two-alternative forced choice perception experiment was performed (16 readers [six radiologists, 10 medical physicists]). A linear mixed-effects statistical model was used to compare detection accuracy between FBP and SAFIRE and to estimate the radiation dose reduction potential of SAFIRE. Results Compared with FBP, SAFIRE reduced noise by a mean of 53% ± 5, lesion contrast by 12% ± 4, and lesion sharpness by 13% ± 10 but increased CNR by 89% ± 19. Detection accuracy was 2% higher on average with SAFIRE than with FBP (P = .03), which translated into an estimated radiation dose reduction potential (±95% confidence interval) of 16% ± 13. Conclusion SAFIRE increases detectability at a given radiation dose (approximately 2% increase in detection accuracy) and allows for imaging at reduced radiation dose (16% ± 13), while maintaining low-contrast detectability of subtle hypoattenuating focal liver lesions. This estimated dose reduction is somewhat smaller than that suggested by past studies. (©) RSNA, 2017 Online supplemental material is available for this article.

    View details for DOI 10.1148/radiol.2017161736

    View details for PubMedID 28170300

  • Duodenal invasion by pancreatic adenocarcinoma: MDCT diagnosis of an aggressive imaging phenotype and its clinical implications. Abdominal radiology (New York) Patel, B. N., Olcott, E. W., Jeffrey, R. B. 2017

    Abstract

    Despite advances in oncologic and imaging technology, pancreatic ductal adenocarcinoma remains a highly deadly disease. The only curative option, pancreaticoduodenectomy or pancreatectomy, carries a significant morbidity. Current imaging plays a role in pre-operative staging to determine the probability of achieve disease-free margins. However, a small but not insignificant number of pancreatic cancers have a relatively higher aggressive biology, despite being resectable based on traditional criteria. Recently, imaging biomarkers that serve as a surrogate for tumors with such aggressive phenotype have been described. These include duodenal invasion and extrapancreatic perineural invasion. This review will focus on the former highlighting the summary of literature supporting duodenal invasion as a surrogate for aggressive disease as well as review its MDCT imaging features.

    View details for PubMedID 28770287

  • Image-Rich Radiology Reports: A Value-Based Model to Improve Clinical Workflow. Journal of the American College of Radiology Patel, B. N., Lopez, J. M., Jiang, B. G., Roth, C. J., Nelson, R. C. 2017; 14 (1): 57-64

    Abstract

    To determine the value of image-rich radiology reports (IRRR) by evaluating the interest and preferences of referring physicians, potential impact on clinical workflow, and the willingness of radiologists to create them.Referring physicians and radiologists were interviewed in this prospective, HIPAA-compliant study. Subject willingness to participate in the study was determined by an e-mail. A single investigator conducted all interviews using a standard questionnaire. All subjects reviewed a video mockup demonstration of IRRR and three methods for viewing embedded images, as follows: (1) clickable hyperlinks to access a scrollable stack of images, (2) scrollable and enlargeable small-image thumbnails, and (3) scrollable but not enlargeable medium-sized images. Questionnaire responses, free comments, and general impressions were captured and analyzed.Seventy-two physicians (36 clinicians, 36 radiologists) were interviewed. Thirty-one clinicians (86%) expressed interest in using IRRR. Seventy-seven percent of subjects believed IRRR would improve communication. Ten clinicians (28%) preferred method 1, 18 (50%) preferred method 2, and 8 (22%) preferred method 3 for embedding images. Thirty clinicians (83%) stated that IRRR would improve efficiency. Twenty-two radiologists (61%) preferred selecting a tool button with a mouse and right-clicking images to embed them, 13 (36%) preferred pressing a function key, and 11 (31%) preferred dictating series and image numbers. The average time radiologists were willing to expend for embedding images was 66.7 seconds.Referring physicians and radiologist both believe IRRR would add value by improving communication with the potential to improve the workflow efficiency of referring physicians.

    View details for DOI 10.1016/j.jacr.2016.07.018

    View details for PubMedID 27692807

  • Characterization of Small (< 4 cm) Focal Renal Lesions: Diagnostic Accuracy of Spectral Analysis Using Single-Phase Contrast-Enhanced Dual-Energy CT. AJR. American journal of roentgenology Patel, B. N., Bibbey, A., Choudhury, K. R., Leder, R. A., Nelson, R. C., Marin, D. 2017; 209 (4): 815–25

    Abstract

    The purpose of this study is to determine whether single-phase contrast-enhanced dual-energy quantitative spectral analysis improves the accuracy of diagnosis of small (< 4.0 cm) renal lesions, compared with conventional single-energy attenuation measurements.In this retrospective study, 136 consecutive patients (95 men and 41 women; mean age, 54 years) with 144 renal lesions (111 benign and 33 malignant) underwent single-energy unenhanced and dual-energy contrast-enhanced CT of the abdomen. For each renal lesion, attenuation measurements were obtained, and an attenuation change of 15 HU or greater was considered evidence of enhancement. Dual-energy spectral attenuation curves were generated for each lesion. The slope of each curve was measured between 40 and 50 keV (λHU40-50), 40 and 70 keV (λHU40-70), and 40 and 140 keV (λHU40-140). Mean lesion attenuation values and spectral attenuation curve parameters were compared between benign and malignant renal lesions by use of the two-sample t test. Diagnostic accuracy was assessed and validated using cross-validation analysis.With the use of cross-validated optimal thresholds at 100% sensitivity, specificity for differentiating between benign and malignant renal lesions improved significantly when both λHU40-70 and λHU40-140 were used, compared with conventional enhancement measurements (93% [103/111; 95% CI, 86-97%] vs 81% [90/111; 95% CI, 73-88%]) (p = 0.02). The sensitivity of λHU40-70 and λHU40-140 was also higher than that of conventional enhancement measurements, although it was not statistically significant.Single-phase contrast-enhanced dual-energy quantitative spectral analysis significantly improves the specificity for characterization of small (< 4.0 cm) renal lesions, compared with conventional single-energy attenuation measurements.

    View details for DOI 10.2214/AJR.17.17824

    View details for PubMedID 28813194

  • Extrapancreatic perineural invasion in pancreatic adenocarcinoma Abdominal Radiology Patel, B. N., Olcott, E., Jeffrey, R. B. 2017
  • Triphasic contrast enhanced CT simulation with bolus tracking for pancreas SBRT target delineation. Practical radiation oncology Godfrey, D. J., Patel, B. N., Adamson, J. D., Subashi, E., Salama, J. K., Palta, M. 2017

    Abstract

    Bolus-tracked multiphasic contrast computed tomography (CT) is often used in diagnostic radiology to enhance the visibility of pancreas tumors, but is uncommon in radiation therapy pancreas CT simulation, and its impact on gross tumor volume (GTV) delineation is unknown. This study evaluates the lesion conspicuity and consistency of pancreas stereotactic body radiation therapy (SBRT) GTVs contoured in the different contrast phases of triphasic CT simulation scans.Triphasic, bolus-tracked planning CT simulation scans of 10 consecutive pancreas SBRT patients were acquired, yielding images of the pancreas during the late arterial (LA), portal venous (PV), and either the early arterial or delayed phase. GTVs were contoured on each phase by a gastrointestinal-specialized radiation oncologist and reviewed by a fellowship-trained abdominal radiologist who specializes in pancreatic imaging. The volumes of the registered GTVs, their overlap ratio, and the 3-dimensional margin expansions necessary for each GTV to fully encompass GTVs from the other phases were calculated. The contrast difference between tumor and normal pancreas was measured, and 2 radiation oncologists rank-ordered the phases according to their value for the lesion-contouring task.Tumor-to-pancreas enhancement was on average much larger for the LA and PV than the delayed phase or early arterial phases; the LA and PV phases were also consistently preferred by the radiation oncologists. Enhancement differences among the phases resulted in highly variable GTV volumes with no observed trends. Overlap ratios ranged from 18% to 75% across all 3 phases, improving to 43% to 91% when considering only the preferred LA and PV phases. GTV expansions necessary to encompass all GTVs ranged from 0.3 to 1.8 cm for all 3 phases, improving slightly to 0.1 to 1.4 cm when considering just the LA and PV phases.For pancreas SBRT, we recommend combining the GTVs from a multiphasic CT simulation with bolus-tracking, including, at a minimum, a Boolean "OR" of the LA and PV phases.

    View details for DOI 10.1016/j.prro.2017.04.008

    View details for PubMedID 28666905

  • Use of a Noise Optimized Monoenergetic Algorithm for Patient-Size Independent Selection of an Optimal Energy Level During Dual-Energy CT of the Pancreas JOURNAL OF COMPUTER ASSISTED TOMOGRAPHY Bellini, D., Gupta, S., Ramirez-Giraldo, J. C., Fu, W., Stinnett, S. S., Patel, B., Mileto, A., Marin, D. 2017; 41 (1): 39-47

    Abstract

    To investigate the impact of a second-generation noise-optimized monoenergetic algorithm on selection of the optimal energy level, image quality, and effect of patient body habitus for dual-energy multidetector computed tomography of the pancreas.Fifty-nine patients (38 men, 21 women) underwent dual-energy multidetector computed tomography (80/Sn140 kV) in the pancreatic parenchymal phase. Image data sets, at energy levels ranging from 40 to 80 keV (in 5-keV increments), were reconstructed using first-generation and second-generation noise-optimized monoenergetic algorithm. Noise, pancreatic contrast-to-noise ratio (CNRpancreas), and CNR with a noise constraint (CNRNC) were calculated and compared among the different reconstructed data sets. Qualitative assessment of image quality was performed by 3 readers.For all energy levels below 70 keV, noise was significantly lower (P ≤ 0.05) and CNRpancreas significantly higher (P < 0.001), with the second-generation monoenergetic algorithm. Furthermore, the second-generation algorithm was less susceptible to variability related to patient body habitus in the selection of the optimal energy level. The maximal CNRpancreas occurred at 40 keV in 98% (58 of 59) of patients with the second-generation monoenergetic algorithm. However, the CNRNC and readers' image quality scores showed that, even with a second-generation monoenergetic algorithm, higher reconstructed energy levels (60-65 keV) represented the optimal energy level.Second-generation noise-optimized monoenergetic algorithm can improve the image quality of lower-energy monoenergetic images of the pancreas, while decreasing the variability related to patient body habitus in selection of the optimal energy level.

    View details for DOI 10.1097/RCT.0000000000000492

    View details for Web of Science ID 000392819500007

    View details for PubMedID 27560021

  • Optimizing window settings for improved presentation of virtual monoenergetic images in dual-energy computed tomography. Medical physics Fu, W., Marin, D., Ramirez-Giraldo, J. C., Choudhury, K. R., Solomon, J., Schabel, C., Patel, B. N., Samei, E. 2017

    Abstract

    Dual-energy computed tomography virtual monoenergetic imaging (VMI) at 40 keV exhibits superior contrast-to-noise ratio (CNR), although practicing radiologists do not consistently prefer it over VMI at 70 keV due to high perceivable noise. We hypothesize that the presentation of 40 keV VMI may be compromised using window settings (i.e., window-and-level values [W-L values]) designed for conventional single-energy CT. This study aimed to devise optimum window settings that reduce the apparent noise and utilize the high CNR of 40 keV VMI, in order to improve the conspicuity of hypervascular liver lesions.Three W-L value adjustment methods were investigated to alter the presentation of 40 keV VMI. To harness the high CNR of 40 keV VMI, the methods were designed to achieve (a) liver histogram distribution, (b) lesion-to-liver contrast, or (c) liver background noise comparable to those perceived in 70 keV VMI. This IRB-approved study included 18 patient abdominal datasets reconstructed at 40 and 70 keV. For each patient, the W-L values were determined using the three methods. For each of the images with default or adjusted W-L values, the noise, contrast, and CNR were calculated in terms of both display space and native CT number (referred to as HU) space. An observer study was performed to compare the 40 keV images with the three adjusted W-L values, and 40 and 70 keV images with default W-L values in terms of noise, contrast, and diagnostic preference. A comparison was also made in terms of the applicability of using patient-specific or patient-averaged W-L values.Using the default W-L values, 40 keV VMI exhibited higher HU CNR than 70 keV VMI by 24.6 ± 14.9% (P < 0.001) but lower display CNR by 38.0 ± 16.4% (P < 0.001). Using adjusted W-L values, 40 keV images showed increased display CNR as compared to 70 keV images, by 21.2 ± 13.1%, 17.4 ± 13.6%, and 24.2 ± 15.9% (P < 0.001) for histogram-, noise-, and contrast equalization methods, respectively. The 40 keV images with all three W-L value adjustment methods showed improved perceived conspicuity (CNR) of liver presentation by 103-120% (P < 0.001), as compared to default W-L values. The qualitative observer study revealed that 40 keV images with noise- and histogram-equalized W-L values were the most preferred, followed by 40 keV images with contrast-equalized W-L values and 70 keV images with default W-L values. The 40 keV images with default W-L values were the least preferred. Patient-specific W-L values offered similar results to those of patient-averaged W-L values.The adjusted W-L values can significantly improve the perception of VMI dataset image quality by improving the actual display CNR.

    View details for DOI 10.1002/mp.12501

    View details for PubMedID 28777467

  • Preoperative Multidetector CT Diagnosis of Extrapancreatic Perineural or Duodenal Invasion Is Associated with Reduced Postoperative Survival after Pancreaticoduodenectomy for Pancreatic Adenocarcinoma: Preliminary Experience and Implications for Patient Care RADIOLOGY Chang, S. T., Jeffrey, R. B., Patel, B. N., DiMaio, M. A., Rosenberg, J., Willmann, J. K., Olcott, E. W. 2016; 281 (3): 816-825

    Abstract

    Purpose To test the hypothesis that patients with pancreatic adenocarcinoma who otherwise are viewed to have resectable disease but have preoperative findings of extrapancreatic perineural invasion (EPNI) and/or duodenal invasion at multidetector computed tomography (CT) have reduced postoperative survival after pancreaticoduodenectomy for pancreatic ductal adenocarcinoma (PDAC). Materials and Methods This study was approved by the institutional review board and complied with HIPAA. The authors retrospectively evaluated 76 consecutive patients with PDAC who underwent preoperative multidetector CT and subsequent pancreaticoduodenectomy. Two radiologists blinded to surgical pathology results and clinical outcome evaluated multidetector CT images for evidence of EPNI and duodenal invasion; discrepancies were resolved by consensus. Also determined for each patient were resected lymph node status, tumor size, surgical margin status, time to progression, and time to death. Data were assessed with the Goodman-Kruskal gamma for correlations among indicators and the log-rank test, Kaplan-Meier estimates, and multivariate Cox proportional hazards regression for survival analysis. Results In univariate analysis, duodenal invasion and/or EPNI on preoperativemultidetector CT images was associated with significantly decreased progression-free survival (P < .0001) and overall survival (P = .0013), and the clinical indicators (lymph node status, tumor size, and surgical margin status) as well as duodenal invasion and/or EPNI showed correlation with each other. In multivariate regression that included multidetector CT findings as well as the three traditional clinical indicators, only duodenal invasion and/or EPNI showed significant independent association with reduction in both modes of survival (P < .0001 and P = .014, respectively). Interobserver agreement was substantial with respect to EPNI and duodenal invasion (κ = 0.691 and 0.682, respectively). Conclusion Patients with evidence of EPNI and/or duodenal invasion on preoperative multidetector CT images have significantly reduced survival after pancreaticoduodenectomy for PDAC. (©) RSNA, 2016.

    View details for DOI 10.1148/radiol.2016152790

    View details for PubMedID 27438167

  • Introduction to Business Strategy JOURNAL OF THE AMERICAN COLLEGE OF RADIOLOGY Patel, B. N., Cespedes, F. V. 2016; 13 (6): 747-749

    View details for DOI 10.1016/j.jacr.2015.11.019

    View details for Web of Science ID 000377053500031

    View details for PubMedID 26774884

  • Deal or No Deal? Negotiation 101 JOURNAL OF THE AMERICAN COLLEGE OF RADIOLOGY Patel, B. N., Rubin, G. D. 2016; 13 (6): 756-758

    View details for DOI 10.1016/j.jacr.2016.03.029

    View details for Web of Science ID 000377053500034

    View details for PubMedID 27262058

  • Effect of a Noise-Optimized Second-Generation Monoenergetic Algorithm on Image Noise and Conspicuity of Hypervascular Liver Tumors: An In Vitro and In Vivo Study AMERICAN JOURNAL OF ROENTGENOLOGY Marin, D., Ramirez-Giraldo, J. C., Gupta, S., Fu, W., Stinnett, S. S., Mileto, A., Bellini, D., Patel, B., Samei, E., Nelson, R. C. 2016; 206 (6): 1222-1232

    Abstract

    The purpose of this study is to investigate whether the reduction in noise using a second-generation monoenergetic algorithm can improve the conspicuity of hypervascular liver tumors on dual-energy CT (DECT) images of the liver.An anthropomorphic liver phantom in three body sizes and iodine-containing inserts simulating hypervascular lesions was imaged with DECT and single-energy CT at various energy levels (80-140 kV). In addition, a retrospective clinical study was performed in 31 patients with 66 hypervascular liver tumors who underwent DECT during the late hepatic arterial phase. Datasets at energy levels ranging from 40 to 80 keV were reconstructed using first- and second-generation monoenergetic algorithms. Noise, tumor-to-liver contrast-to-noise ratio (CNR), and CNR with a noise constraint (CNRNC) set with a maximum noise increase of 50% were calculated and compared among the different reconstructed datasets.The maximum CNR for the second-generation monoenergetic algorithm, which was attained at 40 keV in both phantom and clinical datasets, was statistically significantly higher than the maximum CNR for the first-generation monoenergetic algorithm (p < 0.001) or single-energy CT acquisitions across a wide range of kilovoltage values. With the second-generation monoenergetic algorithm, the optimal CNRNC occurred at 55 keV, corresponding to lower energy levels compared with first-generation algorithm (predominantly at 70 keV). Patient body size did not substantially affect the selection of the optimal energy level to attain maximal CNR and CNRNC using the second-generation monoenergetic algorithm.A noise-optimized second-generation monoenergetic algorithm significantly improves the conspicuity of hypervascular liver tumors.

    View details for DOI 10.2214/AJR.15.15512

    View details for Web of Science ID 000376927300023

    View details for PubMedID 27058192

  • Sonographic Detection of Extracapsular Extension in Papillary Thyroid Cancer. Journal of ultrasound in medicine Kamaya, A., Tahvildari, A. M., Patel, B. N., Willmann, J. K., Jeffrey, R. B., Desser, T. S. 2015; 34 (12): 2225-2230

    Abstract

    To identify and evaluate sonographic features suggestive of extracapsular extension in papillary thyroid cancer.Three board-certified radiologists blinded to the final pathologic tumor stage reviewed sonograms of pathologically proven cases of papillary thyroid cancer for the presence of extracapsular extension. The radiologists evaluated the following features: capsular abutment, bulging of the normal thyroid contour, loss of the echogenic capsule, and vascularity extending beyond the capsule.A total of 129 cases of pathologically proven thyroid cancer were identified. Of these, 51 were excluded because of lack of preoperative sonography, and 16 were excluded because of pathologic findings showing anaplastic carcinoma, follicular carcinoma, or microcarcinoma (<10 mm). The final analysis group consisted of 62 patients with papillary thyroid carcinoma, 16 of whom had pathologically proven extracapsular extension. The presence of capsular abutment had 100% sensitivity for detection of extracapsular extension. Conversely, lack of capsular abutment had a 100% negative predictive value (NPV) for excluding extracapsular extension. Contour bulging had 88% sensitivity for detection of extracapsular extension and when absent had an 87% NPV. Loss of the echogenic capsule was the best predictor of the presence of extracapsular extension, with an odds ratio of 10.23 (P= .034). This sonographic finding had 75% sensitivity, 65% specificity, and an 88% NPV. Vascularity beyond the capsule had 89% specificity but sensitivity of only 25%.Sonographic features of capsular abutment, contour bulging, and loss of the echogenic thyroid capsule have excellent predictive value for excluding or detecting extracapsular extension and may help in biopsy selection, surgical planning, and treatment of patients with papillary thyroid cancer.

    View details for DOI 10.7863/ultra.15.02006

    View details for PubMedID 26518279

  • MDCT Diagnosis of Perineural Invasion Involving the Celiac Plexus in Intrahepatic Cholangiocarcinoma: Preliminary Observations and Clinical Implications. AJR. American journal of roentgenology Raghavan, K., Jeffrey, R. B., Patel, B. N., DiMaio, M. A., Willmann, J. K., Olcott, E. W. 2015; 205 (6): W578-84

    Abstract

    The purpose of this study was to test the hypothesis that soft-tissue infiltration along the celiac plexus and delayed enhancement exceeding two-thirds of the tumor area on preoperative MDCT correlate with histologic evidence of perineural invasion in resected intrahepatic cholangiocarcinomas.Two experienced abdominal radiologists retrospectively reviewed preoperative multiphasic MDCT scans of 20 patients who underwent resection of intrahepatic cholangiocarcinoma, identifying soft-tissue infiltration along the celiac plexus, delayed enhancement exceeding two-thirds of the tumor area, and maximum tumor diameter. Consensus findings were compared with intratumoral perineural invasion in resected intrahepatic cholangiocarcinomas using the Fisher exact test.Six patients had histologic intratumoral perineural invasion, five of whom had soft-tissue infiltration along the celiac plexus on preoperative MDCT, with corresponding 83.3% sensitivity and 92.9% specificity for perineural invasion and significant association between these MDCT and histologic findings (p = 0.002). No patients with histologic perineural invasion had enhancement exceeding two-thirds of the tumor area on MDCT; sensitivity was 0.0% for this finding. Tumor diameter on MDCT was not significantly associated with perineural invasion at histopathology (p = 0.530).Soft-tissue infiltration along the celiac plexus on MDCT is an indicator of perineural invasion in patients with intrahepatic cholangiocarcinoma. The data did not confirm an association between delayed enhancement exceeding two-thirds of the tumor area and perineural invasion. Because perineural invasion from intrahepatic cholangiocarcinoma is associated with a very poor prognosis and is generally a contraindication to surgery, the MDCT diagnosis of celiac plexus perineural invasion in patients with intrahepatic cholangiocarcinoma may have important implications for prognosis and treatment planning.

    View details for DOI 10.2214/AJR.15.14607

    View details for PubMedID 26587947

  • MDCT Diagnosis of Perineural Invasion Involving the Celiac Plexus in Intrahepatic Cholangiocarcinoma: Preliminary Observations and Clinical Implications. AJR. American journal of roentgenology Raghavan, K., Jeffrey, R. B., Patel, B. N., DiMaio, M. A., Willmann, J. K., Olcott, E. W. 2015; 205 (6): W578-84

    View details for DOI 10.2214/AJR.15.14607

    View details for PubMedID 26587947

  • How the radiologist can add value in the evaluation of the pre- and post-surgical pancreas ABDOMINAL IMAGING Patel, B. N., Gupta, R. T., Zani, S., Jeffrey, R. B., Paulson, E. K., Nelson, R. C. 2015; 40 (8): 2932-2944
  • The role of CT-guided percutaneous drainage of loculated air collections: an institutional experience ABDOMINAL IMAGING Patel, B. N., Morgan, M., Tyler, D., Paulson, E., Jaffe, T. A. 2015; 40 (8): 3257-3264

    Abstract

    The purpose of this study is to describe our experience with the role of CT-guided percutaneous drainage of loculated intra-abdominal collections consisting entirely of gas.An IRB-approved retrospective study analyzing patients with air-only intra-abdominal collections over an 8-year period was undertaken. Seven patients referred for percutaneous drainage were included. Size of collections, subsequent development of fluid, and microbiological yield were determined. Clinical outcome was also analyzed.Out of 2835 patients referred for percutaneous drainage between 2004 and 2012, seven patients (5M, 2F; average age 63, range 54-85) met criteria for inclusion with CT showing air-only collections. Percutaneous drain placement (five 8 Fr, one 10 Fr, and one 12 Fr) using Seldinger technique was performed. Four patients (57%) had recently undergone surgery (2 Whipple, 1 colectomy, 1 hepatic resection) while two (29%) had a remote surgery (1 abdominoperineal resection, 1 sigmoidectomy). Despite the lack of detectable fluid on the original CT, 6 patients (86%) had air and fluid aspirated at drainage, 5 (83%) of the aspirates developed positive microbacterial cultures. Four patients (57%) presented with fever at the time of the initial scan, all of whom had positive cultures from aspirated fluid. Four patients (57%) had leukocytosis, all of whom had positive cultures from aspirated fluid.Although relatively rare in occurrence, patients with air-only intra-abdominal collections with signs of infection should be considered for percutaneous management similar to that of conventional infected fluid collections. Although fluid is not visible on CT, these collections can produce fluid that contains organisms.

    View details for DOI 10.1007/s00261-015-0537-2

    View details for PubMedID 26329977

  • Dual-Energy Multidetector-Row Computed Tomography of the Hepatic Arterial System: Optimization of Energy and Material-Specific Reconstruction Techniques JOURNAL OF COMPUTER ASSISTED TOMOGRAPHY Marin, D., Caywood, D. T., Mileto, A., Reiner, C. S., Seaman, D. M., Patel, B. N., Boll, D. T., Nelson, R. C. 2015; 39 (5): 721-729

    Abstract

    To investigate the optimal dual-energy reconstruction technique for the visualization of the hepatic arterial system during dual-energy multidetector computed tomographic (MDCT) angiography of the liver.Twenty-nine nonconsecutive patients underwent dual-energy MDCT angiography of the liver. Synthesized monochromatic (40, 50, 60, and 80 keV) and iodine density data sets were reconstructed. Aortic attenuation, noise, and contrast-to-noise ratio (CNR) were measured. In addition, volume-rendered images were generated and qualitatively assessed by 2 independent readers, blinded to technique. The impact of body size on the readers' scores was also assessed.Aortic attenuation, noise, and CNR increased progressively with decreasing keV and were significantly higher between 40 and 60 keV (P < 0.001). There was a significant improvement of readers' visualization of arterial anatomy at lower monochromatic energies (P < 0.001). Iodine density images yielded significantly higher CNR compared with all monochromatic data sets (P < 0.001). However, iodine density images were scored nondiagnostic by the 2 readers.Synthesized monochromatic images between 40 and 60 keV maximize the magnitude of arterial enhancement and improve visualization of hepatic arterial anatomy at dual-energy MDCT angiography of the liver. Larger body sizes may counteract the benefits of using lower monochromatic energies.

    View details for DOI 10.1097/RCT.0000000000000259

    View details for Web of Science ID 000361750700013

    View details for PubMedID 25938210

  • Organizational Behavior: A Primer JOURNAL OF THE AMERICAN COLLEGE OF RADIOLOGY Patel, B. N. 2015; 12 (8): 805-807

    View details for DOI 10.1016/j.jacr.2015.03.009

    View details for Web of Science ID 000359177000013

    View details for PubMedID 26044644

  • Imaging of Iatrogenic Complications of the Urinary Tract Kidneys, Ureters, and Bladder RADIOLOGIC CLINICS OF NORTH AMERICA Patel, B. N., Gayer, G. 2014; 52 (5): 1101-?

    Abstract

    Iatrogenic complications of various severities may arise from many, if not all, forms of medical and surgical treatment. Most of these occur in spite of proper precautions. Every system in the human body may be affected, and the urinary tract is no exception. Radiologists are often the first to suspect and identify such iatrogenic injuries and, therefore, awareness of the pertinent imaging findings is vital. This review explores and illustrates many of the common and less common iatrogenic complications affecting the kidney, ureters, and bladder.

    View details for DOI 10.1016/j.rcl.2014.05.013

    View details for Web of Science ID 000342882500011

    View details for PubMedID 25173661

  • Sonography of the normal appendix: its varied appearance and techniques to improve its visualization. Ultrasound quarterly Ung, C., Chang, S. T., Jeffrey, R. B., Patel, B. N., Olcott, E. W. 2013; 29 (4): 333-341

    Abstract

    The sonographic identification of the normal appendix is crucial to the success of ultrasound as an effective screening method for diagnosing acute appendicitis. The normal appendix can be challenging to identify on sonography, however, because it is a narrow tubular structure and has variable sonographic appearances. Moreover, the tip of the appendix can be quite variable in location. In this article, we review the various sonographic appearances of the normal appendix and highlight strategies to improve its visualization.

    View details for DOI 10.1097/RUQ.0b013e3182a2aa8e

    View details for PubMedID 24263759

  • Material Density Hepatic Steatosis Quantification on Intravenous Contrast-Enhanced Rapid Kilovolt (Peak)-Switching Single-Source Dual-Energy Computed Tomography JOURNAL OF COMPUTER ASSISTED TOMOGRAPHY Patel, B. N., Kumbla, R. A., Berland, L. L., Fineberg, N. S., Morgan, D. E. 2013; 37 (6): 904-910

    Abstract

    The purpose of this study was to evaluate intravenous (IV) contrast-enhanced single-source rapid kilovolt (peak)-switching dual-energy (RSDE) multidetector computed tomography (CT) material density assessment of hepatic steatosis compared to conventional unenhanced (CU) Multidetector computed tomography (MDCT).This is an institutional review board-approved intrapatient study of 363 consecutive adults (189 men, 174 women; mean age, 59 years) evaluated with multiphasic IV abdominal RSDE. Material density virtual unenhanced water and fat hepatic parenchymal values were measured and correlated to Hounsfield units (HUs) on CU CT using linear regression. Study population was dichotomized into steatotic or nonsteatotic liver parenchyma on the basis of CU liver-spleen (L-S) difference. The RSDE fat(-iodine) values (in milligram per milliliter) were compared (t test), correlated to the L-S difference in HU, and a milligram-per-milliliter fat threshold for clinically significant steatosis was calculated using receiver operator curve (ROC) analysis.Regression analysis revealed r value of 0.86 for mg/mL water (P < 0.001) and 0.87 for milligram-per-milliliter fat (P < 0.001). Twenty-seven participants were excluded from the L-S analysis (splenectomy). A total of 107 (32%) had steatosis (mean L-S, - 6.3; mean fat(-iodine) milligram per milliliter, 1018.4); 229 (68%) had no steatosis (mean L-S, 9.4; milligram per milliliter, 1028.4 [P < 0.001]). The RSDE fat material density measurement correlated to L-S less than 1 with r value of 0.74 (P < 0.001), with an area under receiver operator curve of 0.847. A threshold of 1023-mg/mL fat had 71% sensitivity and 80% specificity, and a threshold of 1027-mg/mL fat had 90% sensitivity and 61% specificity for steatosis.The RSDE milligram-per-milliliter fat values correlate well with hepatic steatosis defined by the L-S difference less than 1 on conventional MDCT. A threshold of 1027 mg/mL can identify 90% of steatotic livers when post-IV contrast RSDE is used, without obtaining additional CU scans. However, regression equations were not helpful to convert an individual participant's milligram-per-milliliter fat or milligram-per-milliliter water-derived from RSDE material density images to CU MDCT HU for the estimation of liver fat content.

    View details for Web of Science ID 000330349000010

    View details for PubMedID 24270112

  • Pitfalls in sonographic evaluation of thyroid abnormalities. Seminars in ultrasound, CT, and MR Patel, B. N., Kamaya, A., Desser, T. S. 2013; 34 (3): 226-235

    Abstract

    Ultrasound of the thyroid has become increasingly common, with evaluation of thyroid nodules representing the main indication for its use. While detection of thyroid nodules with modern high-resolution sonographic equipment is generally not a challenge, pitfalls may occur by which normal structures or pathology in neighboring organs are mistaken for thyroid nodules. Numerous reports in the literature describe various sonographic features of nodules in an attempt to stratify lesions into benign or malignant categories. While neither nodule size nor number is reliable, echogenicity, microcalcifcation, shape, and composition have been reported to be helpful in classifying thyroid nodules. No single feature should be used in isolation, and consensus guidelines have been established as to when fine-needle aspiration is indicated. Pitfalls remain in the evaluation of thyroid nodules demonstrating atypical features, such as cystic papillary carcinomas. Focal presentation of typically diffuse processes, such as Graves' disease and Hashimoto thyroiditis, may mimic malignant nodules, but carcinomas occur in these settings as well as in a background of normal thyroid parenchyma. Finally, because ultrasound is commonly used for surveillance of patients with thyroid carcinoma after thyroidectomy, sonographers should be familiar with the ultrasound appearance of disease recurrence and its mimics.

    View details for DOI 10.1053/j.sult.2012.11.001

    View details for PubMedID 23768889

  • Single-source dual-energy spectral multidetector CT of pancreatic adenocarcinoma: Optimization of energy level viewing significantly increases lesion contrast CLINICAL RADIOLOGY Patel, B. N., Thomas, J. V., Lockhart, M. E., Berland, L. L., Morgan, D. E. 2013; 68 (2): 148-154

    Abstract

    To evaluate lesion contrast in pancreatic adenocarcinoma patients using spectral multidetector computed tomography (MDCT) analysis.The present institutional review board-approved, Health Insurance Portability and Accountability Act of 1996 (HIPAA)-compliant retrospective study evaluated 64 consecutive adults with pancreatic adenocarcinoma examined using a standardized, multiphasic protocol on a single-source, dual-energy MDCT system. Pancreatic phase images (35 s) were acquired in dual-energy mode; unenhanced and portal venous phases used standard MDCT. Lesion contrast was evaluated on an independent workstation using dual-energy analysis software, comparing tumour to non-tumoural pancreas attenuation (HU) differences and tumour diameter at three energy levels: 70 keV; individual subject-optimized viewing energy level (based on the maximum contrast-to-noise ratio, CNR); and 45 keV. The image noise was measured for the same three energies. Differences in lesion contrast, diameter, and noise between the different energy levels were analysed using analysis of variance (ANOVA). Quantitative differences in contrast gain between 70 keV and CNR-optimized viewing energies, and between CNR-optimized and 45 keV were compared using the paired t-test.Thirty-four women and 30 men (mean age 68 years) had a mean tumour diameter of 3.6 cm. The median optimized energy level was 50 keV (range 40-77). The mean ± SD lesion contrast values (non-tumoural pancreas - tumour attenuation) were: 57 ± 29, 115 ± 70, and 146 ± 74 HU (p = 0.0005); the lengths of the tumours were: 3.6, 3.3, and 3.1 cm, respectively (p = 0.026); and the contrast to noise ratios were: 24 ± 7, 39 ± 12, and 59 ± 17 (p = 0.0005) for 70 keV, the optimized energy level, and 45 keV, respectively. For individuals, the mean ± SD contrast gain from 70 keV to the optimized energy level was 59 ± 45 HU; and the mean ± SD contrast gain from the optimized energy level to 45 keV was 31 ± 25 HU (p = 0.007).Significantly increased pancreatic lesion contrast was noted at lower viewing energies using spectral MDCT. Individual patient CNR-optimized energy level images have the potential to improve lesion conspicuity.

    View details for DOI 10.1016/j.crad.2012.06.108

    View details for Web of Science ID 000314440300006

    View details for PubMedID 22889459

  • Three-dimensional volume-rendered multidetector CT imaging of the posterior inferior pancreaticoduodenal artery: its anatomy and role in diagnosing extrapancreatic perineural invasion CANCER IMAGING Patel, B. N., Giacomini, C., Jeffrey, R. B., Willmann, J. K., Olcott, E. 2013; 13 (4): 580-590
  • Radiation Necrosis in the Brain: Imaging Features and Differentiation from Tumor Recurrence RADIOGRAPHICS Shah, R., Vattoth, S., Jacob, R., Manzil, F. F., O'Malley, J. P., Borghei, P., Patel, B. N., Cure, J. K. 2012; 32 (5): 1343-1359

    Abstract

    Radiation necrosis in the brain commonly occurs in three distinct clinical scenarios, namely, radiation therapy for head and neck malignancy or intracranial extraaxial tumor, stereotactic radiation therapy (including radiosurgery) for brain metastasis, and radiation therapy for primary brain tumors. Knowledge of the radiation treatment plan, amount of brain tissue included in the radiation port, type of radiation, location of the primary malignancy, and amount of time elapsed since radiation therapy is extremely important in determining whether the imaging abnormality represents radiation necrosis or recurrent tumor. Conventional magnetic resonance (MR) imaging findings of these two entities overlap considerably, and even at histopathologic analysis, tumor mixed with radiation necrosis is a common finding. Advanced imaging modalities such as diffusion tensor imaging and perfusion MR imaging (with calculation of certain specific parameters such as apparent diffusion coefficient ratios, relative peak height, and percentage of signal recovery), MR spectroscopy, and positron emission tomography can be useful in differentiating between recurrent tumor and radiation necrosis. In everyday practice, the visual assessment of diffusion-weighted and perfusion images may also be helpful by favoring one diagnosis over the other, with restricted diffusion and an elevated relative cerebral blood volume being seen much more frequently in recurrent tumor than in radiation necrosis.

    View details for DOI 10.1148/rg.325125002

    View details for Web of Science ID 000308632900012

    View details for PubMedID 22977022

  • Pulmonary artery pseudoaneurysm arising secondary to cavitary pneumonia. Radiology case reports Smith, C. B., Patel, B. N., Smith, J. P. 2012; 7 (3): 654-?

    Abstract

    Pulmonary artery pseudoaneurysms have classically been associated with the cavitary lesions of reactivation tuberculosis and termed Rasmussen's aneurysm. There have been relatively few case reports of pulmonary artery pseudoaneuryms arising secondary to cavitary pneumonia. We present a case of pulmonary artery pseudoaneurysm occurring secondary to cavitating aspiration pneumonia that was treated successfully with coil embolization.

    View details for DOI 10.2484/rcr.v7i3.654

    View details for PubMedID 27326290

    View details for PubMedCentralID PMC4899676

  • Carbon dioxide as an intravascular imaging agent: review. Current problems in diagnostic radiology Patel, B. N., Kapoor, B. S., Borghei, P., Shah, N. A., Lockhart, M. E. 2011; 40 (5): 208-217

    Abstract

    Patients with renal impairment and/or contrast allergies pose a challenge with regard to diagnostic evaluations. CO(2) may serve as a suitable alternative intravascular contrast agent in these patients with arteriographic applications, including evaluation of peripheral vascular disease, and venographic applications, such as transjugular intrahepatic portosystemic shunt procedure, to name a few. Unique properties of CO(2), such as low viscosity, lack of an allergic reaction, and renal toxicity, have afforded it its diagnostic capabilities. However, certain properties of CO(2) also pose a technical challenge in terms of its delivery. Although it remains a relatively safe alternative contrast agent, potential adverse effects have been reported and exist.

    View details for DOI 10.1067/j.cpradiol.2011.01.002

    View details for PubMedID 21787987

  • Clinico-radiologic profile of spinal cord multiple sclerosis in adults. The neuroradiology journal BAG, A. K., Patel, B. N., Osman, S., Roberson, G. H. 2011; 24 (4): 511-518

    Abstract

    MRI is extremely useful for the assessment of initial disease burden and to identify the dissemination of the multiple sclerosis (MS) in time and space. Though MRI of the spinal cord is not used to establish the diagnosis of MS, spinal cord is frequently involved in this disease and there has been increasing emphasis of the spinal imaging in making clinical decision in the management of MS. We undertook a retrospective study of patients with diagnosed MS: 1) to identify radiologic pattern of spinal cord involvement in MS and 2) to correlate radiologic findings with clinical presentation. We reviewed radiologic records from 2004 to 2009 of patients with abnormal T2 signal intensity of the spinal cord with radiologic concern of demyelinating disease. Patients in this cohort who met the Revised McDonald MS Diagnostic Criteria were included in this study. 166 patients were included in the study. There was preference for cervical spinal cord particularly posterior aspect of the spinal cord. Enhancement of the lesions was rare (4.1%). Mean lesion length was 18.2 mm. The average number of lesions per patient was 2.04. Sensory symptoms were predominating and most of the patients had relapsing-remitting course. Patients with sensory symptoms, bladder and bowel involvement and motor symptoms had almost equally distributed lesions among anterior, posterior and central spinal cord. However, all of the patients presented with posterior column signs and gait abnormality had involvement of the posterior spinal cord. Radiologic manifestation of spinal cord MS is extremely variable and can involve the entire length of the spinal cord. Clinical symptoms may or may not be associated with radiologic presentation of the lesions.

    View details for PubMedID 24059707

  • Severe Contrast Reaction Emergencies: High-fidelity Simulation Training for Radiology Residents and Technologists in a Children's Hospital ACADEMIC RADIOLOGY Tofil, N. M., White, M. L., Grant, M., Zinkan, J. L., Patel, B., Jenkins, L., Youngblood, A. Q., Royal, S. A. 2010; 17 (7): 934-940

    Abstract

    Severe reactions to radiographic contrast agents can be life threatening, and although they are rare, effective recognition and management are essential to improving outcomes. A high-fidelity radiology simulation course for radiology residents and technologists focusing on severe contrast reactions and immediate treatments was designed to test the hypothesis that knowledge would improve with this educational intervention.A prospective pretest and posttest study design was used. Residents and technologists worked in teams of three to five members. Learning objectives focused on demonstrating when and how to use basic life support skills and epinephrine auto-injectors. Each resident and technologist was administered a pretest prior to the start of the case scenarios and a posttest following the debriefing session. Scores from the pretest and posttest for the residents and technologists were compared using a paired-samples t test.Nineteen radiology residents and 11 radiology technologists participated. The average test scores were higher and improved significantly following the simulation experience for both the radiology residents (57% vs 82%, P < .001) and technologists (47% vs 72%, P = .006). Anonymous evaluations demonstrated that the experience was well received by residents and technologists, with 97% of learners (29 of 30) rating the experience as extremely or very helpful. Important learning themes included the knowledge of epinephrine auto-injector use and basic life support skills.High-fidelity simulation for radiology residents and technologists focusing on epinephrine auto-injector use and basic life support skills during the first 5 minutes of a severe contrast reaction can significantly improve recognition and knowledge in treating patients having severe contrast reactions.

    View details for DOI 10.1016/j.acra.2010.03.016

    View details for Web of Science ID 000279508000018

    View details for PubMedID 20471871

  • Intercostal muscle flap reduces the pain of thoracotomy: A prospective randomized trial JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY Cerfolio, R. J., Bryant, A. S., Patel, B., Bartolucci, A. A. 2005; 130 (4): 987-993

    Abstract

    Thoracotomy is associated with significant pain and morbidity.We performed a prospective randomized trial over 4 months. Patients were randomized to a standard posterior-lateral thoracotomy or an identical procedure, except an intercostal muscle was harvested from the lower rib (to protect the intercostal nerve) before chest retraction. To ensure an equal distribution among both groups, patients were stratified by race, sex, and type of pulmonary resection. All patients received similar pain management. Pain was assessed by using multiple pain scores during hospitalization and after discharge. Outcomes assessed were pain scores, spirometric values, analgesic use, and activity level.There were 114 patients. The median time for intercostal muscle harvesting was 3.7 minutes. The numeric pain scores were lower for the intercostal muscle group on postoperative days 1 and 2 and at weeks 1, 2, 3, 4, 8, and 12 (P < .05 for all). In addition, patients in the intercostal muscle group had a smaller decrease in spirometric values, were less likely to be using analgesics, and were more likely to have returned to normal activity.The harvesting of an intercostal muscle flap before chest retraction decreases the pain of thoracotomy and leads to a lower decrease in spirometry. In addition, patients have less pain at 1, 2, 3, 4, 8, and 12 weeks postoperatively and are less likely to be using narcotics. Finally, it offers a pedicled muscle flap that takes little time to harvest and is able to buttress all bronchi after lobectomy.

    View details for DOI 10.1016/j.jtcvs.2005.05.052

    View details for Web of Science ID 000232544000006

    View details for PubMedID 16214509