Correlation of intraprostatic tumor extent with 68-Ga-PSMA distribution in patients with prostate cancer

Abstract

Purpose: We evaluated the diagnostic value and accuracy of prostate specific membrane antigen (PSMA) positron emission tomography (PET) for the intraprostatic delineation of prostate cancer prior to prostatectomy. Methods: We identified a total of six patients with biopsy proven high risk prostate cancer, who were referred to ⁶⁸Ga-PSMA-PET/CT prior to radical prostatectomy to rule out metastases. After prostatectomy, a histology map of the prostate was reconstructed. The histological extension and Gleason Score of each segment of the prostate were compared with PSMA-PET images, resliced to the histological axis. Sensitivity, specificity, positive predictive value, negative predictive value, positive and negative likelihood ratios were calculated. Standard uptake value of each segment was measured and median values were compared. Results: 112/132 segments were eligible for analysis. The correlation of histological results with PSMA-PET images showed a specificity and sensitivity of 92%, respectively. The positive and negative likelihood ratio and the positive and negative predictive value for PSMA-PET detecting prostate cancer were 11.5, 0.09, 96% and 85%, respectively. The median maximum standard uptake value of true positive prostate segments was significantly higher than in 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 and 86.5% and an accuracy of 87.5%. Conclusion: These preliminary results show that the intraprostatic localization and extent of prostate cancer may be estimated by PSMA-PET. This imaging method may be helpful for identifying target lesions prior to prostate biopsy and may support decision-making prior to focal or radical prostate cancer therapy.