Comparison of [18F]DCFPyL and [68Ga]Ga-PSMA-HBED-CC for PSMA-PET Imaging in Patients with Relapsed Prostate Cancer

Gallium-68 (Ga-68)-labeled tracers for imaging expression of the prostate-specific membrane antigen (PSMA) such as the [Ga-68]Ga-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. [F-18]DCFPyL 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 [Ga-68]Ga-PSMA-HBED-CC and [F-18]DCFPyL for clinical use in biochemically relapsed prostate cancer. In 14 selected patients with PSA relapse of prostate cancer, [F-18]DCFPyL PET/X-ray computed tomography (CT) was performed in addition to [Ga-68]Ga-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. All suspicious lesions identified by [Ga-68]Ga-PSMA-HBED-CC were also detected with [F-18]DCFPyL. In three patients, additional lesions were observed using [F-18]DCFPyL PET/CT. The mean SUVmax in the concordant [F-18]DCFPyL PSMA-positive lesions was significantly higher as compared to [Ga-68]Ga-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 [F-18]DCFPyL compared to [Ga-68]Ga-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. [F-18]DCFPyL PET/CT provided a high image quality and visualized small prostate lesions with excellent sensitivity. [F-18]DCFPyL represents a highly promising alternative to [Ga-68]Ga-PSMA-HBED-CC for PSMA-PET/CT imaging in relapsed prostate cancer.