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Suspected clinically localised prostate cancer — MSRA MCQ

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ModeratePI-RADSSuspected clinically localised prostate cancerMSRA

A 56-year-old man is investigated on the suspected prostate cancer pathway. He would be fit for radical treatment if clinically significant prostate cancer were diagnosed. His PSA is 4.9 micrograms/L, MRI-derived prostate volume is 60 mL (PSA density 0.08 ng/mL/mL), digital rectal examination is benign, and there is no family history of prostate cancer. Multiparametric MRI shows a 9 mm peripheral-zone abnormality with linear, wedge-shaped mild hypointensity on the ADC map and corresponding mild high signal on high-b-value diffusion-weighted imaging. There is no focal mass on T2-weighted imaging or extracapsular extension. Dynamic contrast-enhanced imaging shows focal early enhancement at the same site. The radiologist's overall clinical impression is Likert 2. Which interpretation and immediate diagnostic management step is most appropriate?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: A — Classify the lesion as PI-RADS 2 and, after shared decision-making, repeat PSA in 3 to 6 months rather than perform an immediate biopsy

Explanation lettering: C = shown as A · E = shown as B · D = shown as C · A = shown as D · B = shown as E

The peripheral-zone diffusion appearance is linear/wedge-shaped and only mildly restricted, giving a DWI score of 2 rather than 3. In PI-RADS v2.1, dynamic contrast enhancement has a limited upgrading role: positive DCE upgrades an equivocal peripheral-zone DWI score of 3 to overall PI-RADS 4; it does not upgrade a DWI score of 2. The appropriate PI-RADS category is therefore 2. In UK practice, biopsy decisions are based on the MRI Likert assessment rather than PI-RADS alone. With Likert 2, low PSA density (0.08 ng/mL/mL), benign examination and no strong family history, NICE supports discussion of biopsy risks and benefits, with repeat PSA at 3 to 6 months where suspicion is low. A systematic biopsy could be chosen after informed discussion, but is not the most appropriate immediate default here. A is incorrect because there is a genuine, though low-suspicion, MRI abnormality and NICE advises repeat PSA rather than immediate discharge without follow-up. B over-investigates a low-risk MRI pathway. D incorrectly treats positive DCE as sufficient to upgrade DWI 2 to PI-RADS 3. E incorrectly applies the DCE upgrade rule, which applies only when peripheral-zone DWI is score 3.

Reference: NICE NG131: Prostate cancer: diagnosis and management — Recommendations (2019; amended 2021) — https://www.nice.org.uk/guidance/ng131/chapter/recommendations Low cancer yield in PI-RADS 3 upgraded to 4 by dynamic contrast-enhanced MRI: is it time to reconsider scoring categorization? (2023) — https://pubmed.ncbi.nlm.nih.gov/37045981/ PI-RADS v2.1: What has changed and how to report (2021) — https://pubmed.ncbi.nlm.nih.gov/34230862/