Clinical significance of MRI PI-RADS 3 lesions upgraded by dynamic contrast enhancement: the "PI-RADS 3 + 1" subgroup

PI-RADS (Prostate Imaging Reporting and Data System) category 3 lesions harbor a heterogeneous risk of clinically significant prostate cancer (csPCa). They are less frequently biopsied in contemporary practice. Peripheral zone lesions upgraded from PI-RADS 3 to 4 solely based on dynamic contrast enhancement (DCE) ("PI-RADS 3 + 1") may represent a distinct subgroup. We aimed to assess the prevalence of csPCa in this subset.

We conducted a single-center study based on a prospectively maintained database, including consecutive patients with a single PI-RADS 3 + 1 lesion identified at our institution who underwent prostate biopsy between November 2023 and November 2025. csPCa was defined as International Society of Urological Pathology (ISUP) grade group ≥ 2.

Among 55 patients, prostate cancer was detected in 35 cases (64%), including 16 csPCa (29%). Most biopsies (71%) did not yield csPCa. High-grade disease (ISUP GG ≥ 3) was identified in only two patients (4%). csPCa detection rates were higher in patients with PSAd ≥ 0.15 (39% vs 19%). A PSAd-based strategy would have avoided 49% of biopsies but missed 31% of csPCa cases. PSAd showed modest discrimination (AUC 0.65). Lesion size was not associated with csPCa and demonstrated poor discrimination (AUC 0.41).

PI-RADS 3 + 1 lesions appear to represent an intermediate-risk subgroup between conventional PI-RADS 3 and PI-RADS 4 lesions. csPCa was detected in nearly one-third of patients, supporting individualized biopsy decision-making rather than automatic management as conventional PI-RADS 4 lesions.