Clinical significance of volumetric 68 Ga-prostate-specific membrane antigen PET/computed tomography parameters in...

To evaluate the clinical significance of volumetric parameters derived from 68 Ga-prostate-specific membrane antigen (PSMA) PET/computed tomography (CT) for prostate cancer staging and their association with metastatic disease and tumor aggressiveness.

This retrospective study included 206 treatment-naive patients with newly diagnosed, histopathologically confirmed prostate cancer who underwent 68 Ga-PSMA PET/CT for initial staging. Primary tumor maximum standardized uptake value (SUVmax), SUVmean, PSMA tumor volume (PSMA-TV), and total lesion PSMA (TL-PSMA) were measured using a semi-automatic segmentation method. Metastatic disease was defined by PSMA-avid nodal or distant lesions. Imaging parameters were correlated with serum prostate-specific antigen (PSA) levels, Gleason score, International Society of Urological Pathology (ISUP) grade, and D'Amico risk classification. Diagnostic performance was assessed using receiver operating characteristic analysis, and independent predictors of metastasis were evaluated using multivariable logistic regression.

Metastatic disease was detected in 52 of 206 patients (25.2%). TL-PSMA showed the highest diagnostic performance for predicting metastasis [area under the curve (AUC) = 0.80], followed by PSA (AUC = 0.78) and PSMA-TV (AUC = 0.77), whereas SUV-based parameters demonstrated moderate accuracy (AUC = 0.74). In multivariable analysis, TL-PSMA and PSA remained independent predictors of metastatic disease (both P  < 0.01). Volumetric and SUV-based PSMA parameters increased significantly with higher D'Amico risk category, ISUP grade, and Gleason score (all P  < 0.0001). Bilobar intraprostatic PSMA uptake was significantly associated with metastatic disease and high-risk pathological features ( P  < 0.0001).

Volumetric 68 Ga-PSMA PET/CT parameters, particularly TL-PSMA, provide clinically relevant information for prostate cancer staging beyond conventional SUV metrics and PSA. Bilobar intraprostatic PSMA uptake is associated with aggressive disease and increased metastatic risk and may serve as a useful imaging marker in initial staging.