Abstract
Wide variation in prostate cancer detection is seen across all Prostate Imaging Reporting and Data System scores for men with suspected or biopsy-proven untreated prostate cancer who undergo MRI.
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.
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Article History
Received: Mar 26 2019Revision requested: Apr 29 2019
Revision received: Jan 7 2020
Accepted: Feb 13 2020
Published online: Apr 21 2020
Published in print: July 2020