How multiparametric MRI helps identify which patients need biopsy and which can be safely monitored

Prostate cancer is among the most common cancers in men in Switzerland. PSA testing remains the first step in screening, but its low specificity can create uncertainty in general practice: moderately elevated values do not always indicate cancer, while a tumour may also be present when PSA levels are only slightly altered.

Understanding when to refer a patient for further investigation is therefore crucial.

In recent years, multiparametric magnetic resonance imaging (mpMRI) has become the recommended examination between PSA testing and prostate biopsy, as it helps identify which patients truly require tissue sampling and which can be safely monitored.

From PSA to MRI: the new recommended approach

European and Swiss guidelines indicate that mpMRI should be performed before the first biopsy in patients with suspected prostate-confined cancer.

The examination provides accurate mapping of the prostate gland and helps distinguish clinically significant lesions from indolent ones, reducing unnecessary biopsies and overdiagnosis.

For general practitioners, understanding this pathway means being able to provide more targeted counselling and prepare the patient for specialist evaluation with the necessary clinical information.

When to request a prostate MRI

mpMRI is indicated in cases of:

• Persistently elevated or rising PSA

• Abnormal digital rectal examination

• Increased hereditary risk, such as a first-degree family history of prostate, breast or ovarian cancer

Before referral, it is useful to exclude prostatitis or infection, document PSA trends and report any previous biopsies.

The examination should ideally be performed on a 3 Tesla MRI scanner, following a standardised protocol, and reported by experienced radiologists using the PI-RADS classification.

How to interpret the report

The PI-RADS classification expresses the likelihood that a lesion represents clinically significant prostate cancer:

• PI-RADS 4–5: high probability → biopsy recommended

• PI-RADS 3: intermediate probability → decision guided by PSA density

• PI-RADS 1–2: low probability → follow-up if the overall risk is low

PSA density (PSAd) is the ratio between PSA and prostate volume. A value of ≥ 0.15 ng/mL/cc can help refine patient selection, avoiding unnecessary biopsies in men with enlarged prostates or modest PSA elevations.

MRI in follow-up and active surveillance

Beyond initial diagnosis, mpMRI plays an important role in active surveillance and treatment planning.

It enables monitoring of disease progression without the need for repeated biopsies and contributes to staging once cancer has been confirmed.

The contribution of artificial intelligence

Artificial intelligence is increasingly entering clinical practice in prostate MRI.

Algorithms can support radiologists in identifying suspicious areas, calculating prostate volume and automatically comparing successive examinations.

AI does not replace clinical expertise, but it can improve standardisation and efficiency, especially in a context of growing demand.

In summary

When PSA remains elevated or clinical suspicion persists, mpMRI is now the next step before biopsy.

The combination of PI-RADS and PSA density enables better patient selection and supports a more targeted diagnostic pathway, reducing unnecessary invasive procedures.

Effective collaboration between general practitioners, radiology and urology ensures an evidence-based approach that is truly centred on the patient.

Author: Dr Martina Martins
Title: FMH Specialist in Radiology with expertise in urogenital diagnostics