Segment‐based comparison of multiparametric MRI , Gallium‐68‐ PSMA ‐ PET / CT and combined imaging with histopathology in prostate cancer

OBJECTIVES: Ga-PSMA-PET/CT), for detecting histopathologically confirmed prostate cancer (PCa). PATIENTS AND METHODS: This analysis included 97 men from the prospective, interventional, phase II DEPROMP (DEtection rate of clinically significant PROstate cancer by mpMRI and PSMA-PET/CT fusion biopsy) trial who underwent radical prostatectomy with whole-mount histopathological evaluation. All participants received mpMRI and PSMA-PET/CT prior to biopsy. The mpMRI was interpreted according to Prostate Imaging-Reporting and Data System (PI-RADS) version(v)2.1, and PSMA-PET/CT according to Prostate Cancer Molecular Imaging Standardised Evaluation (PROMISE) molecular imaging Tumour-Node-Metastasis (miTNM) criteria. The prostate was divided into 36 anatomical segments based on the PI-RADS v2.1 sector map. Each segment was correlated with histopathological findings from prostatectomy specimens. For each imaging modality, detection rates, sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) were calculated at the segment level. RESULTS: A total of 3492 prostate segments were analysed. Detection rates were 74.1% (95% confidence interval [CI] 72.6-75.5) for mpMRI, 72.2% (95% CI 70.6-73.6) for PSMA-PET/CT, and 79.1% (95% CI 77.7-80.4) for the combined use of mpMRI and PSMA-PET/CT. Sensitivity and specificity were 13.4% and 97.3% for mpMRI, 18.5% and 92.7% for PSMA-PET/CT, and 25.8% and 90.5% for combined mpMRI and PSMA-PET/CT, respectively. Threshold-based receiver operating characteristic analyses yielded an AUC of 0.62 (95% CI 0.54-0.69) for PI-RADS, 0.68 (95% CI 0.63-0.74) for maximum standardised uptake value, and 0.69 (95% CI 0.65-0.74) for molecular imaging PSMA. CONCLUSION: At the segment level, mpMRI and PSMA-PET/CT showed comparable diagnostic accuracy with high specificity but limited sensitivity. Their combination improved sensitivity and overall detection performance, underscoring the complementary value of structural and molecular imaging for lesion localisation and precision management in PCa.