Faculty Bibliography

PURPOSE: To compare boundaries of prostate tumors on MRI and histologic assessment from radical prostatectomy (RP) using detailed software-assisted co-registration, in order to define an optimal treatment margin to achieve complete tumor destruction during image-guided focal ablation. METHODS: 33 patients who underwent 3T MRI before RP were included. A radiologist traced lesion borders on MRI and assigned a suspicion score (SS) from 2-5. 3D reconstructions were created from high-resolution digitalized slides from RP specimens and co-registered to MRI using advanced software. Tumors were compared between histology and MRI using the Hausdorff Distance (HD) and stratified by MRI-SS, Gleason Score (GS), and lesion diameter. Cylindrical volume estimates of treatment effects were used to define the optimal treatment margin. RESULTS: 46 histologically confirmed cancers underwent 3D software-based registration with MRI. MRI underestimated tumor sizes, with the maximal discrepancy between MRI and histologic boundaries for a given tumor averaging 1.99+/-3.1mm (18.5% of the MRI diameter). Boundary underestimation was larger for MRI-SS>/=4 lesions (+3.49+/-2.1mm; p<0.001) and GS>/=7 lesions (+2.48+/-2.8mm; p 0.035). On average, a simulated cylindrical treatment volume based on the MRI boundary missed 14.8% of the tumor volume compared with a simulated cylindrical volume based on the histologic boundary. A simulated treatment volume based on a 9mm treatment margin achieved complete histologic tumor destruction in 100% of patients. CONCLUSION: MRI underestimates histologically-determined tumor boundaries, especially for high MRI-SS and high GS lesions. A 9mm treatment margin around an MRI-visible lesion consistently ensures treatment of the entire histologic tumor volume during focal ablative therapy.

PURPOSE: The aim of this study was to compare coregistration of the bladder wall, bladder masses, and pelvic lymph nodes between sequential and simultaneous PET and MRI acquisitions obtained during hybrid F-FDG PET/MRI performed using a diuresis protocol in bladder cancer patients. METHODS: Six bladder cancer patients underwent F-FDG hybrid PET/MRI, including IV Lasix administration and oral hydration, before imaging to achieve bladder clearance. Axial T2-weighted imaging (T2WI) was obtained approximately 40 minutes before PET ("sequential") and concurrently with PET ("simultaneous"). Three-dimensional spatial coordinates of the bladder wall, bladder masses, and pelvic lymph nodes were recorded for PET and T2WI. Distances between these locations on PET and T2WI sequences were computed and used to compare in-plane (x-y plane) and through-plane (z-axis) misregistration relative to PET between T2WI acquisitions. RESULTS: The bladder increased in volume between T2WI acquisitions (sequential, 176 [139]mL; simultaneous, 255 [146]mL). Four patients exhibited a bladder mass, all with increased activity (SUV, 9.5-38.4). Seven pelvic lymph nodes in 4 patients showed increased activity (SUV, 2.2-9.9). The bladder wall exhibited substantially less misregistration relative to PET for simultaneous, compared with sequential, acquisitions in in-plane (2.8 [3.1]mm vs 7.4 [9.1]mm) and through-plane (1.7 [2.2]mm vs 5.7 [9.6]mm) dimensions. Bladder masses exhibited slightly decreased misregistration for simultaneous, compared with sequential, acquisitions in in-plane (2.2 [1.4]mm vs 2.6 [1.9]mm) and through-plane (0.0 [0.0]mm vs 0.3 [0.8]mm) dimensions. FDG-avid lymph nodes exhibited slightly decreased in-plane misregistration (1.1 [0.8]mm vs 2.5 [0.6]mm), although identical through-plane misregistration (4.0 [1.9]mm vs 4.0 [2.8]mm). CONCLUSIONS: Using hybrid PET/MRI, simultaneous imaging substantially improved bladder wall coregistration and slightly improved coregistration of bladder masses and pelvic lymph nodes.

The contemporary management of prostate cancer (PCa) has been criticized as fostering overdetection and overtreatment of indolent disease. In particular, the historical inability to identify those men with an elevated PSA who truly warrant biopsy, and, for those needing biopsy, to localize aggressive tumors within the prostate, has contributed to suboptimal diagnosis and treatment strategies. This article describes how modern multi-parametric MRI of the prostate addresses such challenges and reduces both overdiagnosis and overtreatment. The central role of diffusion-weighted imaging (DWI) in contributing to MRI's current impact is described. Prostate MRI incorporating DWI achieves higher sensitivity than standard systematic biopsy for intermediate-to-high risk tumor, while having lower sensitivity for low-grade tumors that are unlikely to impact longevity. Particular applications of prostate MRI that are explored include selection of a subset of men with clinical suspicion of PCa to undergo biopsy as well as reliable confirmation of only low-risk disease in active surveillance patients. Various challenges to redefining the standard of care to incorporate solely MRI-targeted cores, without concomitant standard systematic cores, are identified. These include needs for further technical optimization of current systems for performing MRI-targeted biopsies, enhanced education and expertise in prostate MRI among radiologists, greater standardization in prostate MRI reporting across centers, and recognition of the roles of pre-biopsy MRI and MRI-targeted biopsy by payers. Ultimately, it is hoped that the medical community in the United States will embrace prostate MRI and MRI-targeted biopsy, allowing all patients with known or suspected prostate cancer to benefit from this approach.

While initial implementations of prostate MRI suffered from suboptimal performance in tumor detection, technological advances over the past decade have allowed modern multi-parametric prostate MRI (mpMRI) to achieve high diagnostic accuracy for detection, localization, and staging and thereby impact patient management. A particular emerging application of mpMRI is in the pre-biopsy setting to allow for MRI-targeted biopsy, for instance, through real-time MRI/ultrasound fusion, which may help reduce the over-detection of low-risk disease and selectively detect clinically significant cancers, in comparison with use of standard systematic biopsy alone. mpMRI and MRI-targeted biopsy are spreading beyond the large academic centers to increasingly be adopted within small and community practices. Aims of this review article are to summarize the hardware and sequences used for performing mpMRI, explore patient specific technical considerations, delineate approaches for study interpretation and reporting [including the recent American College of Radiology Prostate Imaging Reporting and Data System (PI-RADS) version 2], and describe challenges and implications relating to the widespread clinical implementation of mpMRI.

OBJECTIVE: The apparent diffusion coefficient (ADC) values for benign central zone (CZ) of the prostate were compared with ADC values of benign peripheral zone (PZ), benign transition zone (TZ), and prostate cancer, using histopathologic findings from radical prostatectomy as the reference standard. MATERIALS AND METHODS: The study included 27 patients with prostate cancer (mean [+/- SD] age, 60.0 +/- 7.6 years) who had 3-T endorectal coil MRI of the prostate performed before undergoing prostatectomy with whole-mount histopathologic assessment. Mean ADC values were recorded from the ROI within the index tumor and within benign CZ, PZ, and TZ, with the use of histopathologic findings as the reference standard. ADC values of the groups were compared using paired t tests and ROC curve analysis. RESULTS: The ADC of benign CZ in the right (1138 +/- 123 x 10(-6) mm(2)/s) and left (1166 +/- 141 x 10(-6) mm(2)/s) lobes was not significantly different (p = 0.217). However, the ADC of benign CZ (1154 +/- 129 x 10(-6) mm(2)/s) was significantly lower (p < 0.001) than the ADCs of benign PZ (1579 +/- 197 x 10(-6) mm(2)/s) and benign TZ (1429 +/- 180 x 10(-6) mm(2)/s). Although the ADC of index tumors (1042 +/- 134 x 10(-6) mm(2)/s) was significantly lower (p = 0.002) than the ADC of benign CZ there was no significant difference (p = 0.225) between benign CZ and tumors with a Gleason score of 6 (1119 +/- 87 x 10(-6) mm(2)/s). In 22.2% of patients (6/27), including five patients who had tumors with a Gleason score greater than 6, the ADC was lower in benign CZ than in the index tumor. The AUC of ADC for the differentiation of benign CZ from index tumors was 72.4% (sensitivity, 70.4%; specificity, 51.9%), and the AUC of ADC for differentiation from tumors with a Gleason score greater than 6 was 76.7% (sensitivity, 75.0%; specificity, 65.0%). CONCLUSION: The ADC of benign CZ is lower than the ADC of other zones of the prostate and overlaps with the ADC of prostate cancer tissue, including high-grade tumors. Awareness of this potential diagnostic pitfall is important to avoid misinterpreting the normal CZ as suspicious for tumor.

PURPOSE: To determine the frequency and characteristics of recommendations for additional imaging and/or intervention (RAIs) in abdominal CT and MRI interpretations that might be avoided through comprehensive comparison with all available prior examinations. METHODS: A total of 1,006 RAIs in abdominopelvic CT and MRI reports were retrospectively evaluated. Reports and images from each patient's prior imaging examinations, including those of all relevant body parts and modalities, were reviewed to determine if the RAI could have been avoided based on prior imaging. Frequency and characteristics of such "avoidable" RAIs were evaluated. RESULTS: A total of 41 of 1,006 (4.1%) RAIs were avoidable. The key prior examination that established the RAI as avoidable was a different modality in 53.7% (22 of 41) and on a different body area in 41.5% (17 of 41) of cases, including chest imaging in 31.7% (13 of 41). A total of 83.3% (5 of 6) adrenal RAIs, and 80.0% (4 of 5) liver RAIs were avoidable based on prior chest imaging. The key finding was present on the prior images but was not described in the report in 46.3% (19 of 41) of cases. A greater number of prior examinations were available in cases of avoidable RAIs (mean, 12.2 +/- 16.7) than in those of nonavoidable RAIs (mean, 5.7 +/- 9.5) (P < .001). CONCLUSIONS: A small fraction of RAIs can be avoided by performing a thorough evaluation of all prior imaging examinations, including different modalities and body parts. Nearly half of the key prior examinations did not report the finding, highlighting the importance of directly reviewing relevant images, particularly chest imaging for evaluation of indeterminate upper-abdominal findings. Configuration of PACS for optimized selection and display of relevant examination reports and images may facilitate such comparisons.

PURPOSE: The aim of this study was to evaluate use of the microblogging social network Twitter by academic radiology departments (ARDs) in the United States. METHODS: Twitter was searched to identify all accounts corresponding with United States ARDs. All original tweets from identified accounts over a recent 3-month period (August to October 2014) were archived. Measures of account activity, as well as tweet and link content, were summarized. RESULTS: Fifteen ARDs (8.2%) had Twitter accounts. Ten (5.5%) had "active" accounts, with >/=1 tweet over the 3-month period. Active accounts averaged 711 +/- 925 followers (maximum, 2,885) and 61 +/- 93 tweets (maximum, 260) during the period. Among 612 tweets from active accounts, content most commonly related to radiology-related education (138), dissemination of departmental research (102), general departmental or hospital promotional material (62), departmental awards or accomplishments (60), upcoming departmental lectures (59), other hospital-related news (55), medical advice or information for patients (38), local community events or news (29), social media and medicine (27), and new departmental or hospital hires or expansion (19). Eighty percent of tweets (490 of 612) included 315 unique external links. Most frequent categories of link sources were picture-, video-, and music-sharing websites (89); the ARD's website or blog (83); peer-reviewed journal articles (40); the hospital's or university's website (34), the lay press (28), and Facebook (14). CONCLUSIONS: Twitter provides ARDs the opportunity to engage their own staff members, the radiology community, the department's hospital, and patients, through a broad array of content. ARDs frequently used Twitter for promotional and educational purposes. Because only a small fraction of ARDs actively use Twitter, more departments are encouraged to take advantage of this emerging communication tool.

PURPOSE: To determine multi-parametric MRI features that can help differentiate malignant omental caking from benign omental thickening in the setting of portal hypertension. METHODS: We identified 19 patients with an abnormal omentum on MRI and an available reference standard: 11 patients with portal hypertension and benign omental thickening (9 male, 2 female, mean age 58 +/- 6 years) and 8 patients with metastatic omental caking (4 male, 4 female, mean age 61 +/- 13 years). Criteria for benign omental thickening were no evidence of malignancy for at least 24 months of follow-up (n = 7), negative ascites cytology (n = 2), or absence of malignancy on pathologic analysis of liver explant (n = 2). Criteria for omental malignancy were positive omental biopsy (n = 6) or ascites cytology (n = 2). Two radiologists (R1 and R2) evaluated characteristics of the thickened omentum on MRI. RESULTS: Findings occurring with significantly higher frequency in malignant omental caking were hyperintensity on high b-value diffusion-weighted imaging (DWI) (R1 88% vs. 0%, R2 88% vs. 0%), hyperenhancement (R1 75% vs. 0%, R2 75% vs. 0%), and convex outer omental contour (R1 88% vs. 0%, R2 75% vs. 9%) (all p /= 0.058). CONCLUSION: Abnormal signal on DWI, hyperenhancement, and convex outer contour are helpful MRI features to differentiate malignant from benign omental thickening.

PURPOSE: To perform a survey-based assessment of patients' knowledge of radiologic imaging examinations, including patients' perspectives regarding communication of such information. METHODS: Adult patients were given a voluntary survey before undergoing an outpatient imaging examination at our institution. Survey questions addressed knowledge of various aspects of the examination, as well as experiences, satisfaction, and preferences regarding communication of such knowledge. RESULTS: A total of 176 surveys were completed by patients awaiting CT (n = 45), MRI (n = 41), ultrasound (n = 46), and nuclear medicine (n = 44) examinations. A total of 97.1% and 97.8% of patients correctly identified the examination modality and the body part being imaged, respectively. A total of 45.8% correctly identified whether the examination entailed radiation; 51.1% and 71.4% of patients receiving intravenous or oral contrast, respectively, correctly indicated its administration. A total of 78.6% indicated that the ordering physician explained the examination in advance; among these, 72.1% indicated satisfaction with the explanation. A total of 21.8% and 20.5% indicated consulting the Internet, or friends and family, respectively, to learn about the examination. An overall understanding of the examination was reported by 70.8%. A total of 18.8% had unanswered questions about the examination, most commonly regarding examination logistics, contrast-agent usage, and when results would be available. A total of 52.9% were interested in discussing the examination with a radiologist in advance. Level of understanding was greatest for CT and least for nuclear medicine examinations, and lower when patients had not previously undergone the given examination. CONCLUSIONS: Patients' knowledge of their imaging examinations is frequently incomplete. The findings may motivate initiatives to improve patients' understanding of their imaging examinations, enhancing patient empowerment and contributing to patient-centered care.

OBJECTIVE: The objective of our study was to evaluate manuscript metrics pertaining to AJR submissions, assessing the pathway from manuscript submission to publication, including the reviewer allocation time, decisions rendered, timing of decisions rendered, and time to publication. MATERIALS AND METHODS: Six hundred ninety-six unsolicited Original Research manuscripts submitted to the AJR between July 1, 2012, and December 21, 2012, were included in this retrospective analysis. Metrics pertaining to manuscripts' decision status and associated timelines were extracted by journal editorial staff and assessed using standard summary statistics. RESULTS: For new submissions, decisions rendered were as follows: Accept, 0.3%; Minor Revision, 8.5%; Major Revision, 19.7%; Reject, 65.1%; and Reject Without Review, 6.5%. For first and second resubmissions, 40.0-55.2% of manuscripts representing a Major Revision and 91.5-94.7% of manuscripts representing a Minor Revision were accepted; 100% of manuscripts undergoing a third resubmission were accepted; 98.3% and 84.7% of manuscripts receiving at first submission a decision of Minor Revision and Major Revision, respectively, ultimately achieved acceptance. The time (mean +/- SD) to review a new submission was 30.5 +/- 43.1 days (Accept), 42.7 +/- 27.4 days (Minor Revision), 39.4 +/- 17.6 days (Major Revision), and 40.2 +/- 20.3 days (Reject) and decreased with each subsequent resubmission to 6.3 +/- 6.3 days (Accept) for third resubmissions. The mean days for authors to submit a first resubmission was 21.1 +/- 15.3 days (Minor Revision) and 73.7 +/- 65.1 days (Major Revision) and decreased with each subsequent resubmission to 9.8 +/- 11.3 days (Minor Revision) and 27.0 +/- 0.0 days (Major Revision) for third resubmissions. The mean time from acceptance to publication was 242.5 +/- 47.5 days. CONCLUSION: The observed metrics may provide valuable insights for authors and for AJR editorial staff in ongoing efforts to shorten turnaround times from manuscript submission to publication.