Correlation of Intraprostatic Tumor Extent with ⁶⁸Ga-PSMA Distribution in Patients with Prostate Cancer

We evaluated the diagnostic value and accuracy of prostate-specific membrane antigen (PSMA) PET for the intraprostatic delineation of prostate cancer before prostatectomy.

We identified 6 patients with biopsy-proven high-risk prostate cancer who were referred for (68)Ga-PSMA PET/CT before radical prostatectomy to rule out metastasis. After prostatectomy, a histologic map of the prostate was reconstructed. The histologic extent and Gleason score of each segment of the prostate were compared with (68)Ga-PSMA PET images resliced to the histologic axis. Sensitivity, specificity, positive and negative predictive value, and positive and negative likelihood ratios were calculated. The SUV of each segment was measured, and median values were compared.

Of the 132 segments, 112 were eligible for analysis. The correlation of histologic results with (68)Ga-PSMA PET images showed a specificity and sensitivity of 92%. The positive and negative likelihood ratio and the positive and negative predictive value for detection of prostate cancer on (68)Ga-PSMA PET were 11.5, 0.09, 96%, and 85%, respectively. The median SUVmax of true-positive prostate segments was significantly higher than that of true-negative segments (11.0 ± 7.8 vs. 2.7 ± 0.9, P< 0.001), and a cutoff of 4 revealed a sensitivity and specificity of 86.5% and an accuracy of 87.5%.

These preliminary results show that the intraprostatic localization and extent of prostate cancer may be estimated by (68)Ga-PSMA PET. This imaging method may be helpful for identifying target lesions before prostate biopsy and may support decision making before focal or radical therapy.