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PI-RADS — MSRA MCQ

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ModeratePI-RADSMSRA

A 59-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 6.8 micrograms/L, digital rectal examination is benign and he has not had a previous prostate biopsy. Multiparametric MRI identifies a 12 mm focal lesion in the right posterolateral peripheral zone. It is markedly hypointense on the ADC map and markedly hyperintense on high-b-value diffusion-weighted imaging (DWI score 4). There is no focal early enhancement on dynamic contrast-enhanced imaging and no extracapsular extension. Which reporting 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: D — Classify the lesion as PI-RADS 4 and offer an MRI-influenced prostate biopsy

Explanation lettering: D = shown as B · B = shown as D

The lesion is PI-RADS 4. In the peripheral zone, DWI is the dominant sequence. Marked focal hypointensity on ADC with corresponding marked high-b-value DWI hyperintensity in a lesion measuring less than 1.5 cm is DWI score 4 and gives an overall PI-RADS category 4. Negative dynamic contrast enhancement does not downgrade a peripheral-zone DWI 4 lesion; DCE is principally used to upgrade an equivocal DWI 3 peripheral-zone lesion when enhancement is positive. In UK practice, MRI findings reported as Likert 3 or above should prompt an MRI-influenced prostate biopsy in a person suitable for radical treatment. Therefore, this high-suspicion lesion requires biopsy rather than PSA surveillance. A is incorrect because absent enhancement does not reduce a DWI 4 lesion to PI-RADS 3. C correctly selects biopsy but misclassifies the lesion; PI-RADS 3 would apply to an equivocal, rather than markedly restricted, peripheral-zone lesion. D is inappropriate because a PI-RADS 4-equivalent MRI finding warrants biopsy. E overcalls the lesion: PI-RADS 5 requires a lesion at least 1.5 cm or definite extraprostatic extension/invasive behaviour.

Reference: NICE NG131: Prostate cancer: diagnosis and management — MRI and biopsy recommendations (2019; page checked August 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/ Limited reproducibility of PI-RADS v2.1 upgrading rule subcategorization in MRI-visible peripheral zone lesions (2026) — https://pubmed.ncbi.nlm.nih.gov/42302440/