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Suspected clinically localised prostate cancer — MSRA MCQ

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HardPI-RADSSuspected clinically localised prostate cancerMSRA

A 60-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 5.8 micrograms/L, MRI-derived prostate volume is 64 mL (PSA density 0.09 ng/mL/mL), digital rectal examination is benign, PSA has been stable over 12 months, and he has no family history of prostate cancer. He has not previously had a prostate biopsy. Multiparametric MRI shows a 9 mm discrete lesion in the peripheral zone. It is markedly hypointense on the ADC map and markedly hyperintense on high-b-value diffusion-weighted imaging. Dynamic contrast-enhanced imaging shows no focal early enhancement, and there is no extracapsular extension. Which PI-RADS v2.1 interpretation and immediate diagnostic management is most appropriate?

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

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Correct answer: A — Assign PI-RADS 4 (overall MRI Likert 4) and offer an MRI-influenced prostate biopsy.

This is a peripheral-zone lesion, in which DWI is the dominant PI-RADS v2.1 sequence. Focal marked hypointensity on ADC with corresponding marked high signal on high-b-value DWI is DWI score 4 when the lesion is under 1.5 cm. Therefore, this 9 mm lesion is PI-RADS 4. PI-RADS 5 would require a lesion of at least 1.5 cm or definite extraprostatic extension; neither is present. Negative dynamic contrast enhancement does not downgrade a peripheral-zone DWI score 4 lesion. DCE is principally used to upgrade an equivocal peripheral-zone DWI score 3 lesion to PI-RADS 4 when enhancement is positive. In UK practice, NICE recommends reporting MRI using a Likert scale and offering MRI-influenced prostate biopsy when the Likert score is 3 or above. The low PSA density, stable PSA and absent family history would support surveillance only in a person with a low-risk MRI result (Likert 1 or 2); they do not override a Likert 4 MRI result. Option E incorrectly treats absent enhancement as making the lesion equivocal. Option C misclassifies marked focal diffusion restriction as low risk.

Reference: NICE NG131: Prostate cancer: diagnosis and management — MRI and biopsy recommendations (Published 2019; last updated 15 December 2021) — 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/ Dynamic Contrast Enhanced Magnetic Resonance Imaging Improves Classification of Prostate Lesions: A Study of Pathological Outcomes on Targeted Prostate Biopsy (2017) — https://pubmed.ncbi.nlm.nih.gov/28709889/