Effect of Prostate MRI Interpretation Experience on PPV Using PI-RADS Version 2: A 6-Year Assessment Among Eight Fellowship-Trained Radiologists.

Abstract

<b>BACKGROUND.</b> Understanding the effect of specific experience in prostate MRI interpretation on diagnostic performance would help inform the minimum interpretation volume to establish proficiency. <b>OBJECTIVE.</b> The purpose of this article is to assess for an association between increasing experience in prostate MRI interpretation and change in radiologist-level PPVs for PI-RADS version 2 (v2) categories 3, 4, and 5. <b>METHODS.</b> This retrospective study included prostate MRI examinations performed between July 1, 2015, and August 13, 2021, that were assigned a PI-RADS v2 category of 3, 4, or 5 and with an MRI-ultrasound fusion biopsy available as the reference standard. All examinations were among the first 100-200 prostate MRI examinations interpreted using PI-RADS v2 by fellowship-trained abdominal radiologists. Radiologists received feedback through a quality assurance program. Radiologists' experience levels were classified using progressive subsets of 50 interpreted examinations. Change with increasing experience in distribution of individual radiologists' whole-gland PPVs for Gleason sum score 7 or greater prostate cancer, stratified by PI-RADS category, was assessed by hierarchic linear mixed models. <b>RESULTS.</b> The study included 1300 prostate MRI examinations in 1037 patients (mean age, 66 ± 7 [SD] years), interpreted by eight radiologists (median, 13 years of postfellow-ship experience; range, 5-22 years). Aggregate PPVs were 20% (68/340) for PI-RADS category 3, 49% (318/652) for category 4, and 71% (220/308) for category 5. Interquartile ranges (IQRs) of PPVs overlapped for category 4 (51%; IQR, 42-60%) and category 5 (70%; IQR, 54-75%) for radiologists' first 50 examinations. IQRs of PPVs did not overlap between categories of greater experience; for example, at the 101-150 examination level, PPV for category 3 was 24% (IQR, 20-29%), category 4 was 55% (IQR, 54-63%), and category 5 was 81% (IQR, 77-82%). Hierarchic modeling showed no change in radiologists' absolute PPV with increasing experience (category 3, <i>p</i> = .27; category 4, <i>p</i> = .71; category 5, <i>p</i> = .38). <b>CONCLUSION.</b> Absolute PPVs at specific PI-RADS categories did not change during radiologists' first 200 included examinations. However, resolution of initial overlap in IQRs indicates improved precision of PPVs after the first 50 examinations. <b>CLINICAL IMPACT.</b> If implementing a minimum training threshold for fellowship-trained abdominal radiologists, 50 prostate MRI examinations may be sufficient in the context of a quality assurance program with feedback.