Faculty Bibliography

RATIONALE AND OBJECTIVES: The aim of this study was to assess prostate cancer detection using a broad range of computed b-values up to 5000 s/mm2. MATERIALS AND METHODS: This retrospective Health Insurance Portability and Accountability Act-compliant study was approved by an institutional review board with consent waiver. Forty-nine patients (63 +/- 8 years) underwent 3T prostate magnetic resonance imaging before prostatectomy. Examinations included diffusion-weighted imaging (DWI) with b-values of 50 and 1000 s/mm2. Seven computed DWI image sets (b-values: 1000, 1500, 2000, 2500, 3000, 4000, and 5000 s/mm2) were generated by mono-exponential fit. Two blinded radiologists (R1 [attending], R2 [fellow]) independently evaluated diffusion weighted image sets for image quality and dominant lesion location. A separate unblinded radiologist placed regions of interest to measure tumor-to-peripheral zone (PZ) contrast. Pathologic findings from prostatectomy served as reference standard. Measures were compared between b-values using the Jonckheere-Terpstra trend test, Spearman correlation coefficient, and generalized estimating equations based on logistic regression for correlated data. RESULTS: As b-value increased, tumor-to-PZ contrast and benign prostate suppression for both readers increased (r = +0.65 to +0.71, P 6 tumor was highest for R1 at b1500-3000 (90%-93%) and for R2 at 1500-2500 (78%-80%). The positive predictive value for tumor for R1 was similar from b1000 to 4000 (93%-98%) and for R2 was similar from b1500 to 4000 (88%-94%). CONCLUSIONS: Computed b-values in the range of 1500-2500 s/mm2 (but not higher) were optimal for prostate cancer detection; b-values of 1000 or 3000-5000 exhibited overall lower performance.

OBJECTIVE: The purpose of this article is to highlight the potential challenges associated with the Prostate Imaging Reporting and Data System, version 2 (PI-RADS v2), and to offer, when possible, suggestions and ideas for improvement. CONCLUSION: PI-RADS v2 offers clear improvements to its earlier version and will greatly benefit the prostate MRI community. Nonetheless, caution remains on the basis of early user experience, and potential ambiguities and gaps of PI-RADS v2 are noted. Continued data-driven clarification and refinement of the guidelines will be invaluable for PI-RADS v2 to achieve its goal of improving patient care.

RATIONALE AND OBJECTIVES: This study aimed to assess the most common publication types in radiology journals, as well as temporal trends and association with citation frequency. MATERIALS AND METHODS: PubMed was searched to extract all published articles having the following "Publication Type" indices: "validation studies," "meta-analysis," "clinical trial," "comparative study," "evaluation study," "guideline," "multicenter study," "randomized study," "review," "editorial," "case report," and "technical report." The percentage of articles within each category published within clinical radiology journals was computed. Normalized percentages for each category were also computed on an annual basis. Citation counts within a 2-year window following publication were obtained using Web of Science. Overall trends were assessed. RESULTS: Publication types with the highest fraction in radiology journals were technical reports, evaluation studies, and case reports (4.8% to 5.8%). Publication types with the lowest fraction in radiology journals were randomized trials, multicenter studies, and meta-analyses (0.8% to 1.5%). Case reports showed a significant decrease since 1999, with accelerating decline since 2007 (P = 0.002). Publication types with highest citation counts were meta-analyses, guidelines, and multicenter studies (8.1 +/- 10.7 to 12.9 +/- 5.1). Publication types with lowest citation counts were case reports, editorials, and technical reports (1.4 +/- 2.4 to 2.9 +/- 4.3). The representation in radiology journals and citation frequency of the publication types showed weak inverse correlation (r = -0.372). CONCLUSIONS: Radiology journals have historically had relatively greater representation of less frequently cited publication types. Various strategies, including methodological training, multidisciplinary collaboration, national support networks, as well as encouragement of higher level of evidence by funding agencies and radiology journals themselves, are warranted to improve the impact of radiological research.

The significant advances in magnetic resonance imaging (MRI) hardware and software, sequence design, and postprocessing methods have made diffusion-weighted imaging (DWI) an important part of body MRI protocols and have fueled extensive research on quantitative diffusion outside the brain, particularly in the oncologic setting. In this review, we summarize the most up-to-date information on DWI acquisition and clinical applications outside the brain, as discussed in an ISMRM-sponsored symposium held in April 2015. We first introduce recent advances in acquisition, processing, and quality control; then review scientific evidence in major organ systems; and finally describe future directions. J. Magn. Reson. Imaging 2016.

PURPOSE: The aim of this report is to describe our early experience with radiologist-led direct public education about imaging-based cancer screening examinations, with a focus on the level of satisfaction and the educational impact reported by session participants. METHODS: Subspecialty radiologists provided 1-hour educational sessions to small lay public audiences covering breast, prostate, and lung cancer screening, focusing on key radiologic screening tests. Subsequently, session participants completed a survey pertaining to their levels of satisfaction and the perceived impact of the sessions on knowledge of the diseases and relevant screening tests; results from all topic sessions were pooled for analysis. RESULTS: One hundred nineteen participants attended a total of 144 sessions. The large majority of respondents agreed or strongly agreed that the sessions increased their understanding (95.4%), they gained information not obtained from clinic visit (88.1%), seeing radiology images helped their understanding (92.6%), they felt more involved in their own care (85.8%), they felt more prepared to undergo screening tests (87.4%), they were satisfied with the sessions' format (93.3%) and content (96.2%), their main questions were answered (88.3%), they would be interested in similar future radiologist-led sessions (88.5%), and they would recommend the sessions to friends (93.9%). The provided information (43.1%) and images (34.7%) were identified as the most helpful aspects of the sessions. CONCLUSION: Radiologist-led direct public education sessions about imaging-based cancer screening examinations yield high levels of audience satisfaction and add value to the public's understanding of the role of radiology and radiologists. Our experience may provide an encouraging model for other radiology practices in pursuing similar endeavors.

PURPOSE: To explore whole-lesion histogram analysis of the hepatobiliary phase (HBP) defect in indeterminate hypovascular liver lesions for predicting progression to arterial-enhancing hepatocellular carcinoma (HCC). METHODS: Twenty patients undergoing gadoxetic acid-enhanced MRI for HCC screening with 12 degrees and 25 degrees flip angle (FA) HBP acquisitions demonstrating an indeterminate lesion showing HBP hypointensity but no arterial enhancement were included. Volumes-of-interest were placed on HBP defects, from which histogram metrics were obtained. Associations between these metrics and progression to arterial-enhancing HCC on follow-up imaging were investigated. Lesions were also assessed for the presence of a signal abnormality on conventional sequences. RESULTS: 40% of lesions progressed to arterial-enhancing HCC; 60% were stable at >/=6 months follow-up. Neither T2-hyperintensity increased diffusion signal nor portal/equilibrium phase washout was different between progressing and nonprogressing lesions (p = 1.0). Among direct signal intensity-based measures (overall mean; mean of bottom 10th, 10-25th, and 25-50th percentiles), area-under-the-curve (AUC) for prediction of progression to arterial-enhancing HCC was consistently higher at 25 degrees (range 0.619-0.657) than at 12 degrees (range 0.512-0.548). However, at both FAs, the four measures with highest AUC were measures related to lesion texture and heterogeneity [standard deviation (SD), coefficient of variation (CV), skewness, and entropy], having AUC of 0.655-0.750 at 12 degrees and 0.686-0.800 at 25. The metric with highest AUC at 12 degrees was SD (AUC = 0.750) and at 25 degrees was CV (AUC = 0.800). CONCLUSION: Whole-lesion histogram HBP measures of indeterminate hypovascular liver lesions may help predict progression to arterial-enhancing HCC by reflecting greater lesion heterogeneity, particularly at higher FA. Larger studies are therefore warranted.

OBJECTIVE: The purpose of this study was to characterize trends related to retracted publications within radiology journals. MATERIALS AND METHODS: PubMed was queried to identify all articles with the publication type "retracted publication" or "notification of retraction." Articles published within radiology journals were identified using Journal Citation Reports' journal categories. Available versions of original articles and publication notices were accessed from journal websites. Citations to retracted publications were identified using Web of Science. Overall trends were assessed. RESULTS: Forty-eight retracted original research articles were identified within radiology journals since 1983, which included 1.1% of all PubMed "retracted publication" entries. Distinct PubMed entries were available for the retracted publication and retraction notification in 39 of 48 articles. The original PDF was available for 37 articles, although the articles were not watermarked as retracted in 23 cases. In six cases with a watermarked PDF, further searches identified nonwatermarked versions. Original HTML versions were available for 13 articles but 11 were not watermarked. The mean (+/- SD) delay between publication and retraction was 2.7 +/- 2.8 years (range, 0-16 years). The mean number of citations to retracted articles was 10.9 +/- 17.1 (range, 0-94 citations). Reasons for retraction included problematic or incorrect methods or results (although it typically was unclear whether these represented honest errors or misconduct) in 33.3% of cases, complete or partial duplicate publication in 33.3% of cases, plagiarism in 14.6% of cases, a permission issue in 8.3% of cases, the publisher's error in 6.3% of cases, and no identified reason in 6.3% of cases. One or no retractions occurred annually from 1986 to 2001, although two or more retractions occurred annually in nine of the 12 years from 2002 through 2013. CONCLUSION: Retraction represents an uncommon, yet potentially increasing, issue within radiology journals that publishers have inconsistently and insufficiently addressed. Greater awareness and training in proper biomedical research conduct, as well as establishment and enforcement of standardized publishers' policies, are warranted.

OBJECTIVES: To evaluate the cancer detection rates (CDR) for men undergoing 12 core systematic prostate biopsy with negative prebiopsy mpMRI (NegMR). MATERIALS & METHODS: Clinical data from consecutive men undergoing prostate biopsy with prebiopsy 3T mpMRI from December 2011 to August 2014 were reviewed from an IRB approved prospective database. Prebiopsy mpMRI was read by a single radiologist and men with NegMR prior to biopsy were identified for this analysis. Clinical features, CDR, and NPV rates were summarized. RESULTS: Seventy five men underwent SPB with a NegMRI during the study period. For the entire cohort, men with no prior biopsy, men with prior negative biopsy, and men enrolled in active surveillance protocols, overall CDR was 18.7%, 13.8%, 8.0% and 38.1%, respectively, and detection of Gleason sum >/= 7 (GS>/=7) cancer was 1.3%, 0%, 4.0% and 0%, respectively. The NPV for all cancers was 81.3%, 86.2%, 92.0%, and 61.9%, and for GS>/=7 cancer was 98.7%, 100%, 96.0% and 100%, respectively. CONCLUSIONS: Negative prebiopsy mpMRI confers an overall NPV of 82% on 12 core biopsy for all cancer and 98% for GS>/=7. Based upon biopsy indication, these findings assist in prebiopsy risk stratification for detection of high risk disease and may provide guidance in the decision to pursue biopsy

PURPOSE: The aim of this study was to evaluate multisequence magnetic resonance imaging (MRI) in detecting local recurrence after transurethral resection for bladder cancer. METHODS: Thirty-six patients with bladder cancer with previous transurethral resection underwent bladder MRI incorporating T2-weighted imaging, diffusion-weighted imaging, and delayed contrast-enhanced T1-weighted imaging, followed by cystoscopy. Two radiologists (R1 and R2) evaluated examinations for suspicious findings. RESULTS: Forty-seven percent of patients had recurrent tumor at cystoscopy and biopsy. Using multisequence MRI, sensitivity and specificity were 67% and 81% for R1 and 73% and 62% for R2. Both readers missed 1 high-grade pathologic stage T1 recurrent tumor; otherwise, all missed tumors were low-grade pathologic stage Ta lesions. All false positives for R1 and 7 of 9 false positives for R2 were in patients receiving previous bacillus Calmette-Guerin therapy. Furthermore, 40% to 50% of solitary abnormalities and 83% to 100% of multifocal abnormalities were tumor recurrences; 12% to 20% of smooth wall thickening, 50% to 75% of irregular wall thickening, and 88% to 100% of papillary masses were tumor recurrences. CONCLUSIONS: Although multisequence MRI exhibited moderate performance for detecting recurrent tumor, nearly all missed tumors were low grade and noninvasive.