MRI and PSMA-PET each detected under a fifth of cancer-bearing prostate segments; combined was better

Design

Secondary analysis of a prospective phase II trial with whole-mount histology

Population

97 men having mpMRI and PSMA-PET/CT before radical prostatectomy; 3,492 segments

Primary outcome

Segment-level diagnostic performance vs histopathology

Effect

Sensitivity 13.4% (MRI), 18.5% (PSMA-PET), 25.8% (combined); specificity 90.5-97.3%

In the phase II DEPROMP trial (BJU International, 18 October 2026), 97 men had both multiparametric MRI and gallium-68 PSMA-PET/CT before biopsy and then radical prostatectomy with whole-mount pathology. The prostate was divided into 36 segments, giving 3,492 for comparison.

At segment level, sensitivity and specificity were 13.4% and 97.3% for MRI, 18.5% and 92.7% for PSMA-PET/CT, and 25.8% and 90.5% combined. Detection rates were 74.1%, 72.2% and 79.1%. AUC was 0.62 for PI-RADS, 0.68 for maximum SUV and 0.69 for PSMA expression score.

Segment-level analysis is a stern test, because it counts every small focus of cancer. The practical point is that both modalities are specific but miss much of the cancer's extent, and they find somewhat different areas, which matters for focal therapy and surgical planning.

• Do not treat a negative segment on MRI or PSMA-PET as free of cancer when planning focal therapy.
• Consider combining MRI and PSMA-PET for mapping where focal or nerve-sparing decisions depend on lesion location.
• Continue to use MRI as the first-line pre-biopsy test; this study did not change that.
• Interpret segment-level sensitivity as a measure of extent, not of whether significant cancer is found at all.

Why it matters

Focal therapy and nerve-sparing plans rest on where the cancer is, and both scans miss much of it.

Don't overread it

With 97 men from one trial, these results do not support replacing MRI with PSMA-PET for diagnosis.

The statistics, in plain English

Sensitivity here is per segment, so a low figure means many small cancer areas were not seen, not that most men's cancers were missed.

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