Ability of 68 Ga-PSMA PET/CT SUVmax to differentiate ISUP GG2 from GG3 in intermediate-risk prostate cancer: A single-center retrospective study of 147 patients.

OBJECTIVE: To evaluate the ability of 68 Ga-PSMA PET/CT maximum standard uptake value (SUVmax) to distinguish prostate cancer (PCa) International Society of Urological Pathology ISUP grade group (GG) 2 and GG3. METHODS: The PET/CT images and data of 147 patients were analyzed retrospectively, and the SUVmax of the index lesions were measured. The receiver operating characteristic curve was used to analyze the diagnostic value of PET/CT for PCa. The correlation between SUVmax and ISUP GG was analyzed. A logistic regression model was established with SUVmax and was validated to predict its value of diagnosing intermediate- and high-risk PCa (ihPCa). RESULTS: Of the 147 patients, 112 cases were PCa (76.2%), and 35 cases were benign lesions (23.8%). There was a significant difference between the benign and the malignant groups (p < 0.05). The median SUVmax of ihPCa was significantly higher than that of the benign and low-risk groups (p < 0.05). The median SUVmax of GG3 was significantly higher than that of the GG2 group (p < 0.05). There were no statistically significant SUVmax differences among GG3, GG4, and GG5 groups (p > 0.05). The specificity and the positive predictive value of 68 Ga-PSMA PET/CT in the diagnosis of PCa were 97% and 99% with cut-off SUVmax of 6.94, while the specificity and the positive predictive value of ihPCa were 95% and 96% with cut-off SUVmax of 10.12. CONCLUSION: 68 Ga-PSMA PET/CT can reliably distinguish GG2 from GG3 PCa.