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Suspected clinically localised prostate cancer — MSRA MCQ

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ModeratePI-RADSSuspected clinically localised prostate cancerMSRA

A 68-year-old man is investigated on the suspected prostate cancer pathway. He would be suitable for radical treatment if clinically significant prostate cancer is diagnosed. His PSA is 9.1 micrograms/L, MRI-derived prostate volume is 45 mL and digital rectal examination is benign. Multiparametric MRI demonstrates a 17 mm focal lesion in the left posterolateral peripheral zone. It is markedly hypointense on the ADC map and markedly hyperintense on high-b-value diffusion-weighted imaging. There is no definite extracapsular extension. Dynamic contrast-enhanced imaging shows no focal early enhancement. Which reporting interpretation and immediate diagnostic management is most appropriate?

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Correct answer: B — Classify the lesion as PI-RADS v2.1 category 5 and offer MRI-influenced prostate biopsy.

This is a peripheral-zone lesion, where diffusion-weighted imaging is the dominant PI-RADS v2.1 sequence. Marked hypointensity on ADC with corresponding marked high-b-value DWI hyperintensity indicates marked diffusion restriction. In the peripheral zone, a lesion with these features measuring more than 1.5 cm is PI-RADS category 5, even without definite extracapsular extension. Negative dynamic contrast enhancement does not downgrade a peripheral-zone lesion already scored highly on DWI. NICE recommends MRI-influenced biopsy for an MRI Likert score of 3 or more; a PI-RADS 5 lesion represents a highly suspicious MRI target and should proceed to MRI-influenced biopsy. A category 3 interpretation underestimates the marked diffusion restriction and size. Category 4 would be appropriate for an otherwise similar markedly diffusion-restricting peripheral-zone lesion smaller than 1.5 cm. Surveillance without biopsy is inappropriate for this highly suspicious lesion. Staging imaging may become appropriate after histological confirmation and risk stratification, but it does not replace diagnostic biopsy in this setting.

Reference: NICE NG131: Prostate cancer: diagnosis and management — MRI and biopsy recommendations (2019; last updated March 2026) — https://www.nice.org.uk/guidance/ng131/chapter/recommendations PI-RADS v2.1: What has changed and how to report (2021) — https://pubmed.ncbi.nlm.nih.gov/34230862/