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Suspected clinically localised prostate cancer — MSRA MCQ

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HardPI-RADSSuspected clinically localised prostate cancerMSRA

A 65-year-old man is investigated on the suspected prostate cancer pathway. He would be suitable for radical treatment if clinically significant prostate cancer were diagnosed. His PSA is 8.2 micrograms/L, MRI-derived prostate volume is 44 mL (PSA density 0.19 ng/mL/mL), and digital rectal examination is benign. He has not previously had a prostate biopsy. Multiparametric MRI identifies a 16 mm anterior transition-zone lesion. It is heterogeneous, moderately T2-hypointense and has obscured margins (T2-weighted score 3). It is markedly hypointense on ADC and markedly hyperintense on high-b-value diffusion-weighted imaging; its size gives a DWI score of 5. There is no extracapsular extension. Dynamic contrast-enhanced imaging shows no focal early enhancement. The reporting radiologist assigns an overall Likert score of 4. Which interpretation and immediate diagnostic management is most appropriate?

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Correct answer: B — PI-RADS 4, with offer of an MRI-influenced prostate biopsy

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

This is a transition-zone lesion, so T2-weighted imaging is the dominant sequence for PI-RADS assessment. Its heterogeneous, moderately hypointense appearance with obscured margins gives a T2 score of 3. However, the lesion has marked diffusion restriction and measures 16 mm, giving DWI score 5. In PI-RADS v2.1, a transition-zone lesion with T2 score 3 and DWI score 5 is upgraded to PI-RADS 4; DWI score 5 does not itself make the overall category PI-RADS 5 when the dominant T2 score is 3. Negative dynamic contrast enhancement does not downgrade a transition-zone lesion. The UK management decision is based on the MRI Likert score: NICE recommends MRI-influenced biopsy for Likert 3 or above. This man has Likert 4 disease and is fit for radical treatment, so biopsy should be offered. A is wrong because the lesion is upgraded beyond PI-RADS 3 and surveillance is inappropriate. C incorrectly treats negative enhancement as reassurance. D incorrectly applies the 15 mm DWI threshold as an automatic overall PI-RADS 5 designation. E gives the appropriate biopsy direction but misclassifies the lesion.

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