⁶⁸Ga-PSMA-HBED-CC PET/CT detects location and extent of primary prostate cancer

Abstract

We evaluated the accuracy of ⁶⁸Ga-PSMA-HBED-CC (⁶⁸Ga-PSMA) positron emission tomography/computed tomography (PET/CT) to localize cancer in the prostate and surrounding tissue at initial diagnosis. Methods: Twenty-one patients with biopsy-proven prostate cancer (PCa) underwent ⁶⁸Ga-PSMA PET/CT at a median of 4 (range: 0 to 47) days prior to radical prostatectomy. Based on a 6-segment model, the Gleason score (GS) and segmental tumor burden (STBHP) as determined by histopathology were correlated with maximum standardized uptake value (SUV_max) and tumor burden as determined by different SUV cut-off values for ⁶⁸Ga-PSMA PET (STBPET1-6). Furthermore, the involvement of seminal vesicles and other extracapsular extension were assessed by histopathology and PET/CT. Results: Histopathology positive (+) segments (n = 100 of 126, 79%) demonstrated a significantly higher mean±standard deviation (SD) SUV_max (11.8±7.6) as compared to histopathology negative (-) segments (4.9±2.9; p<0.001). Receiver-operating-characteristic revealed an optimal SUV_max cut-off value of 6.5 for discrimination of histopathology+/- segments (area under the curve, AUC: 0.84; p<0.001) which gave 67% sensitivity, 92% specificity, 97% positive predictive value, 42% negative predictive value, and 72% accuracy. STBPET3 as determined by 2xSUVblood+2xSD correlated best with STBHP (Pearson’s rho=0.68; p<0.001; mean difference±SD = 19±15%). PET/CT correctly detected invasion of seminal vesicles (n = 11 of 21 patients; 52%) with 86% accuracy, and tumor spread through the capsule (n = 12; 57%) with 71% accuracy. Conclusion: ⁶⁸Ga-PSMA PET/CT accurately detects location and extent of primary prostate cancer. Our preliminary findings warrant further investigation of ⁶⁸Ga-PSMA PET/CT in conjunction with needle biopsy.