Faculty Bibliography

PURPOSE/OBJECTIVE:To demonstrate the generalizability of PRECISION findings and apply the PRECISION biopsy strategy to a contemporary cohort to characterize cancers missed by employing this strategy. MATERIALS AND METHODS/METHODS:629 men biopsied between 2/2015-9/2018 met PRECISION inclusion criteria. Men with PI-RADS 1-2 MRI were only biopsied if high clinical suspicion for cancer. Missed cancers were defined as prostate cancer (PCa) identified uniquely on systematic biopsy (SB) in men with PI-RADS 3-5 MRI, or on either SB or MRI-targeted prostate biopsy (MRI-TB) in men with PI-RADS 1-2 MRI. Outcomes included 1) clinically-significant PCa (csPCa), ≥Gleason grade group (GG) 2, detection rate (CDR), 2) missed csPCa rate upon application of PRECISION biopsy strategy, 3) GG distribution, core size, spatial orientation, and oncologic risk among missed cancers. RESULTS:Application of the PRECISION biopsy strategy to the study cohort resulted in avoidance of biopsy in 28%, similar MRI-TB CDR to PRECISION, reduction of GG1 CDR by 60%, and reduction of csPCa CDR by 19%. Missed csPCa were often <6 mm (54.5%), GG2 (67.3%), and low-risk by clinical nomogram (74.6%). GG1 cancers identified uniquely on SB were often contralateral to MRI target (46.4%), while missed csPCa was predominantly ipsilateral (81%). Limitations include biopsy of only men with high-risk clinical features among PIRADS 1-2 MRI, potentially overestimating the csPCa CDR. CONCLUSIONS:The study cohort demonstrated generalizability of PRECISION findings. Applying the PRECISION biopsy strategy greatly reduces GG1 CDR, while missing a small number of csPCa, typically small volume, low-risk, and GG2. Missed csPCa are predominantly ipsilateral to MRI target, possibly representing targeting error.

Introduction & Objectives: AUA, EAU and NICE now recommend multiparametric (mp)MRI prior to all prostate biopsies, including initial. This creates a massive increase in demand on the limited resource of access to MRI. Biparametric (bp)MRI, without dynamic contrast enhancement (DCE) series, is rapidly gaining interest as a faster, cheaper, less invasive way of performing prostate MRI with the goal of maintaining diagnostic accuracy. Using an online training tool, the global BooMeR Study assesses accuracy and variation in reading of bpMRI.
Material(s) and Method(s): A free bpMRI version of the online mpMRI training program MRI PRO (prostatemristudy.com) was promoted via email, Twitter and LinkedIn from August to October 2019 to target radiologists and urologists around the world. MRI PRO is an interactive program which matches 300 prostate mpMRIs acquired and reported to PIRADS v.2 standard to wholemount radical prostatectomy in positive MRIs and template transperineal biopsy histology for negative MRIs. The bpMRI version matches 50 cases, without any DCE series. We designated true PIRADS 4 or 5 as true positive and true PIRADS 1 or 2 as true negative. True PIRADS 3 (equivocal) cases were excluded from analysis. MRI PRO's proprietary analysis tool was used to compare users' responses.
Result(s): 59 prostate MRI readers registered for the study. 33% were radiologists, 67% were urologists and all respondents were consultants or fellows. 59%, 12%, 9%, 20% were from Europe, Asia-Pacific, North America, or elsewhere, respectively. 33% had previously read over 100 prostate mpMRIs. A total of 1,090 cases were completed, for a mean of 18.4 cases per reader. 15 readers completed all 50 cases. The overall specificity and sensitivity was 78% and 71% respectively. Cohorts of experienced vs inexperienced readers were then compared where readers who had performed more than 4 cases were included. Readers with over 100 previous cases of experience [n=13] had specificity of 77.7% (95% CI 70.9 - 84.4) and sensitivity of 77.2% (95% CI 70.2, 84.2). Readers with less than 100 previous cases of experience [n=18] had a specificity of 53.8%, 95% CI [41.9%, 65.7%] and sensitivity of 64.4%, 95% CI [59.9%, 68.8%]. The difference in sensitivity (p=0.044) and specificity (p=0.003) between the two cohorts were statistically significant). PIRADS 3 reporting was 3.9% vs 8.2% in the experienced vs inexperienced groups.
Conclusion(s): Preliminary BooMeR Study results suggest variation in bpMRI reporting accuracy and likelihood of reporting PIRADS 3 are associated with reader experience. Adequate training and quality assurance in reporting bpMRI is essential.
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Background Prostate MRI is used widely in clinical care for guiding tissue sampling, active surveillance, and staging. The Prostate Imaging Reporting and Data System (PI-RADS) helps provide a standardized probabilistic approach for identifying clinically significant prostate cancer. Despite widespread use, the variability in performance of prostate MRI across practices remains unknown. Purpose To estimate the positive predictive value (PPV) of PI-RADS for the detection of high-grade prostate cancer across imaging centers. Materials and Methods This retrospective cross-sectional study was compliant with the HIPAA. Twenty-six centers with members in the Society of Abdominal Radiology Prostate Cancer Disease-focused Panel submitted data from men with suspected or biopsy-proven untreated prostate cancer. MRI scans were obtained between January 2015 and April 2018. This was followed with targeted biopsy. Only men with at least one MRI lesion assigned a PI-RADS score of 2-5 were included. Outcome was prostate cancer with Gleason score (GS) greater than or equal to 3+4 (International Society of Urological Pathology grade group ≥2). A mixed-model logistic regression with institution and individuals as random effects was used to estimate overall PPVs. The variability of observed PPV of PI-RADS across imaging centers was described by using the median and interquartile range. Results The authors evaluated 3449 men (mean age, 65 years ± 8 [standard deviation]) with 5082 lesions. Biopsy results showed 1698 cancers with GS greater than or equal to 3+4 (International Society of Urological Pathology grade group ≥2) in 2082 men. Across all centers, the estimated PPV was 35% (95% confidence interval [CI]: 27%, 43%) for a PI-RADS score greater than or equal to 3 and 49% (95% CI: 40%, 58%) for a PI-RADS score greater than or equal to 4. The interquartile ranges of PPV at these same PI-RADS score thresholds were 27%-44% and 27%-48%, respectively. Conclusion The positive predictive value of the Prostate Imaging and Reporting Data System was low and varied widely across centers. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Milot in this issue.