PI-RADS v2.1 Narrative Review: Where It Stands and Where It's Heading

PI-RADS v2.1 standardizes prostate mpMRI reporting but inter-reader variability and transition-zone ambiguity persist. Adding PSA density aids PI-RADS 3 triage; biparametric MRI matches diagnostic accuracy contrast-free; AI narrows the experience gap. Prospective multi-site vali…

• Narrative review of PubMed/Web of Science literature through December 2025 covering PI-RADS v2.1 performance, limitations, and emerging adjuncts; no primary patient-level data or pooled meta-analytic statistics reported.
• PSA density integration is highlighted as the practical near-term tool for risk-stratifying ambiguous PI-RADS 3 lesions; biparametric MRI (no contrast) shows comparable accuracy to full mpMRI (exact sensitivity/specificity figures not reported in source).
• Key limitation of the review itself: narrative (not systematic/meta-analytic) design limits quantitative synthesis; authors call for prospective, multi-center studies to validate AI and advanced quantitative MRI (amide proton transfer, restriction spectrum imaging, MR elastography) approaches.

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