Risk Stratification of Prostate Imaging Reporting and Data System ( PI ‐ RADS 3) Lesions in the Peripheral and Transition Zones Using Clinical and Quantitative MRI Markers

BACKGROUND: Prostate Imaging Reporting and Data System (PI-RADS) 3 lesions often undergo biopsy despite a low positive predictive value (< 25%) for clinically significant prostate cancer (csPCa), defined as International Society of Urological Pathology (ISUP) Grade Group ≥ 2. PURPOSE: To determine whether mean apparent diffusion coefficient (mADC), alone or with prostate-specific antigen (PSA)-based metrics, improves zone-specific PI-RADS 3 classification for csPCa detection. STUDY TYPE: Retrospective, single-center. POPULATION: One hunderd and seventy-one males (71 ± 8 years) with 191 PI-RADS 3 lesions who underwent multiparametric MRI and targeted biopsy. FIELD STRENGTH/SEQUENCE: 3 T, T2-weighted turbo spin-echo imaging, single-shot echo-planar diffusion-weighted imaging, and fat-suppressed dynamic contrast-enhanced T1-weighted gradient echo sequences. ASSESSMENT: mADC, PSA, PSA density (PSAD), prostate volume, and body mass index were analyzed. STATISTICAL TESTS: Logistic regression and receiver operating characteristic (ROC) analyses assessed associations with malignancy and diagnostic performance. RESULTS: /s). In the PZ, mADC alone, and with PSAD showed no significantly different area under the curve (AUC, 0.79 vs. 0.80, p = 0.28). A combination of mADC and PSAD would result in hypothetical estimated lesion-level biopsy avoidance. In the TZ, combining mADC with PSAD yielded significantly higher AUC than mADC alone (0.88 vs. 0.77, difference: 0.109 [95% CI: 0.010-0.208]). This combination would result in hypothetical estimated lesion-level biopsy avoidance in 58 of 82 non-cancers (71%) while missing one csPCa in the PZ, and 27 of 35 noncancerous lesions while missing one csPCa in TZ. DATA CONCLUSION: mADC combined with PSAD showed a significant increase in discrimination in the TZ, suggesting improved PI-RADS 3 stratification; independent validation is required before clinical implementation. EVIDENCE LEVEL: 3. TECHNICAL EFFICACY: 2.