Comparison of [ 18 F]PSMA-1007 with [ 68 Ga]Ga-PSMA-11 PET/CT in Restaging of Prostate Cancer Patients with PSA Relapse.

This study aimed to compare the diagnostic performance of [ 18 F]PSMA-1007 positron emission tomography/computed tomography (PET/CT) ( 18 F-PSMA) and [ 68 Ga]Ga-PSMA-11 PET/CT ( 68 Ga-PSMA) by identifying prostate-specific antigen (PSA) threshold levels for optimal detecting recurrent prostate cancer (PC) and to compare both methods. Retrospectively, the study included 264 patients. The performances of 18 F-PSMA and 68 Ga-PSMA in relation to the pre-scan PSA were assessed by receiver operating characteristic (ROC) curve. 18 F-PSMA showed PC-lesions in 87.5% (112/128 patients), while 68 Ga-PSMA identified them in 88.9% (121/136). For 18 F-PSMA biochemical recurrent (BCR) patients treated with radical prostatectomy (78/128, patient group: F-RP), a PSA of 1.08 ng/mL was found to be the optimal cut-off level for predicting positive and negative scans (AUC = 0.821; 95%, CI: 0.710-0.932), while for prostatectomized 68 Ga-PSMA BCR-patients (89/136, patient group: Ga-RP), the cut-off was 1.84 ng/mL (AUC = 0.588; 95%, CI: 0.410-0.766). In patients with PSA < 1.08 ng/mL (F-RP) 76.3% and <1.84 ng/mL (Ga-RP) 78.6% scans were positive, whereas patients with PSA ≥ 1.08 ng/mL (F-RP) or 1.84 ng/mL (Ga-RP) had positive scan results in 100% and 91.5% ( p < 0.001/ p = 0.085). The identified PSA thresholds for PSMA-mappable PC lesions in BCR-patients (RP) showed a better separation for 18 F-PSMA with regard to the distinguishing of positive and negative PC-lesions compared to 68 Ga-PSMA. However, the two PSMA PET/CT tracers gave similar overall findings.