Comparison of 18FDCFPyL and 68GaGa-PSMA-HBED-CC for PSMA-PET Imaging in Patients with Relapsed Prostate Cancer

PURPOSE: Gallium-68 (Ga-68)-labeled tracers for imaging expression of the prostate-specific membrane antigen (PSMA) such as the (68)GaGa-PSMA-HBED-CC have already demonstrated high potential for the detection of recurrent prostate cancer. However, compared to Ga-68, a labeling with fluorine-18 (F-18) would offer advantages with respect to availability, production amount, and image resolution. (18)FDCFPyL is a promising F-18-labeled candidate for PSMA-positron emission tomography (PET) imaging that has been recently introduced. In the current study, we aimed to compare (68)GaGa-PSMA-HBED-CC and (18)FDCFPyL for clinical use in biochemically relapsed prostate cancer. PROCEDURES: In 14 selected patients with PSA relapse of prostate cancer, (18)FDCFPyL PET/X-ray computed tomography (CT) was performed in addition to (68)GaGa-PSMA-HBED-CC PET/CT. A systematic comparison was carried out between results obtained with both tracers with regard to the number of detected PSMA-positive lesions, the standardized uptake value (SUV)max and the lesion to background ratios. RESULTS: All suspicious lesions identified by (68)GaGa-PSMA-HBED-CC were also detected with (18)FDCFPyL. In three patients, additional lesions were observed using (18)FDCFPyL PET/CT. The mean SUVmax in the concordant (18)FDCFPyL PSMA-positive lesions was significantly higher as compared to (68)GaGa-PSMA-HBED-CC (14.5 vs. 12.2, p = 0.028, n = 15). The mean tumor to background ratios (n = 15) were significantly higher for (18)FDCFPyL compared to (68)GaGa-PSMA-HBED-CC using kidney, spleen, or parotid as reference organs (p = 0.006, p = 0.002, p = 0.008), but no significant differences were found using the liver (p = 0.167) or the mediastinum (p = 0.363) as reference organs. CONCLUSION: (18)FDCFPyL PET/CT provided a high image quality and visualized small prostate lesions with excellent sensitivity. (18)FDCFPyL represents a highly promising alternative to (68)GaGa-PSMA-HBED-CC for PSMA-PET/CT imaging in relapsed prostate cancer.