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PI-RADS — MSRA MCQ

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HardPI-RADSMSRA

A 59-year-old man is investigated on the suspected prostate cancer pathway. He is fit for radical treatment if clinically significant prostate cancer is diagnosed. His PSA is 6.0 micrograms/L, MRI-derived prostate volume is 58 mL (PSA density 0.10 ng/mL/mL), and digital rectal examination is benign. He has not previously had a prostate biopsy. Multiparametric MRI demonstrates a 13 mm transition-zone lesion that is heterogeneous, moderately T2-hypointense and has obscured margins (T2-weighted score 3). It is focally mildly hypointense on ADC and mildly hyperintense on high-b-value DWI (DWI score 3). Dynamic contrast-enhanced imaging shows focal early enhancement corresponding to the lesion. There is no extracapsular extension. The radiologist gives an overall MRI Likert score of 3. Which interpretation and immediate diagnostic management is most appropriate?

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Correct answer: A — Classify the lesion as PI-RADS 3 because T2-weighted imaging is dominant in the transition zone and dynamic contrast enhancement does not upgrade it, and offer an MRI-influenced prostate biopsy

This is a transition-zone (TZ) lesion with a T2-weighted score of 3 and DWI score of 3. In PI-RADS v2.1, T2-weighted imaging is the dominant sequence for TZ assessment. Unlike an equivocal peripheral-zone lesion, focal positive dynamic contrast enhancement (DCE) does not upgrade a TZ lesion from PI-RADS 3 to PI-RADS 4. The appropriate PI-RADS category is therefore 3. The subsequent UK diagnostic decision is determined by the overall MRI assessment: NICE recommends offering an mpMRI-influenced prostate biopsy when the MRI Likert score is 3 or more. A PSA density below 0.15 ng/mL/mL may inform risk discussion in a low-risk MRI, but it does not override a Likert 3 result. Mapping transperineal template biopsy is not recommended as an initial assessment outside a clinical trial. The lesion is not a PI-RADS 2 benign prostatic hyperplasia nodule because it is non-circumscribed with obscured margins and has equivocal focal diffusion abnormality.

Reference: Prostate Imaging Reporting and Data System Version 2.1: 2019 Update of Prostate Imaging Reporting and Data System Version 2 (2019) — https://pubmed.ncbi.nlm.nih.gov/30898406/ Prostate MRI based on PI-RADS version 2: how we review and report (2016) — https://pubmed.ncbi.nlm.nih.gov/27067275/ Prostate cancer: diagnosis and management, NG131, MRI and biopsy recommendations (2019) — https://www.nice.org.uk/guidance/ng131/chapter/Recommendations