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 mADC was significantly lower in cancers than non‐cancers in 133 PZ lesions (885 ± 165 vs. 1068 ± 168 × 10 −6 mm 2 /s) and 58 TZ lesions (670 ± 127 vs. 832 ± 179 × 10 −6 mm 2 /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.