PSA for predicting 68Ga-PSMA−, 18F-FDG+ lesions in CRPC patients. Area under curve (AUC) was 0.715 (95% CI, 0.556–0.874; P = 0.02), and PSA of 7.9 ng/mL was determined for predicting patients with at least 1 68Ga-PSMA−, 18F-FDG+ lesion. Sensitivity and specificity for predicting at least 1 68Ga-PSMA−, 18F-FDG+ lesion were 61.5% (8/13) and 79.1% (34/43), respectively.