- Design
- Secondary analysis of a prospective phase II trial with whole-mount histology
- Population
- 97 men, 3,492 prostate segments
- Primary outcome
- Segment-level detection, sensitivity and specificity
- Effect
- Sensitivity 13.4% MRI, 18.5% PSMA-PET, 25.8% combined; specificity 97.3%, 92.7%, 90.5%
This analysis took 97 men from the phase II DEPROMP trial who had both multiparametric MRI and gallium-68 PSMA-PET/CT before biopsy and went on to radical prostatectomy. Each prostate was divided into 36 segments on the PI-RADS sector map, giving 3,492 segments compared with whole-mount histology.
Detection rates were 74.1% for MRI, 72.2% for PSMA-PET/CT and 79.1% combined. At segment level, sensitivity was low and specificity high for each: 13.4% and 97.3% for MRI, 18.5% and 92.7% for PSMA-PET/CT, and 25.8% and 90.5% combined. AUCs were 0.62 for PI-RADS and 0.68 to 0.69 for PSMA measures.
Segment-level sensitivity is a demanding test, and it is much lower than patient-level detection because small foci in individual segments are easily missed. The practical message is about mapping, not diagnosis: when precise localisation matters, as for focal therapy or targeted biopsy, the two scans add to each other. Neither should be read as excluding cancer in an unlit segment.
- Do not read a negative segment on MRI or PSMA-PET as free of cancer.
- Consider combining MRI and PSMA-PET findings when planning focal therapy or targeted biopsy.
- Keep systematic biopsy cores alongside targeted cores where segment mapping matters.
- Remember that patient-level detection is far higher than segment-level sensitivity.
Why it matters
Focal treatment depends on knowing where the cancer is, and a single scan misses much of the tumour map.
Don't overread it
Segment-level results from 97 men do not mean either scan misses most clinically significant cancers at patient level.
The statistics, in plain English
A segment sensitivity of 13.4% means MRI flagged only about one in seven segments that contained cancer, while specificity of 97.3% means it rarely flagged a benign one. Combining scans doubled sensitivity at a small cost in specificity.
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