18F-PSMA-1007 is a new radiopharmaceutical for the detection of prostate cancer with potential benefits over the registered 18F-Fluciclovine (Axumin). The main potential benefit is the higher detection rate of PSMA compared to Fluciclovin in the low PSA range. It may therefore be more sensitive in detecting local disease in case of biochemical recurrens. The investigators aim to compare the detection efficacy of 18F-PSMA-1007 to 18F-Fluciclovin in prostate cancer patients with biochemical recurrence (PSA levels 0.2-5 ng/ml).

Rationale: 18F-PSMA-1007 is a new radiopharmaceutical for detection of prostate cancer with potential benefits over 18F-Fluciclovine, such as higher detection rates at low PSA levels and small lesions, lower bone marrow uptake and higher tumour-background ratio. Therefore, 18F-PSMA-1007 PET may be more sensitive in detecting local recurrence and metastases of prostate cancer. However, Fluciclovine is a registered tracer, whereas PSMA-1007 is not registered, and therefore there is pressure to use fluciclovine instead of PSMA-1007. Therefore more comparative data are urgently needed.

Objective: Main objective is to compare detection efficacy of 18F-PSMA-1007 PET-CT to 18F-Fluciclovine, in patients with early biochemical recurrence of prostate cancer.

Study design: Comparative phase II diagnostic study Study population: 50 males >18 years, with biochemical recurrence of prostate cancer and PSA-levels between 0.2-5.0 ng/mL. About 25 of the patients must have PSA-levels between 0.2-1.0 ng/mL. Contra-indications: claustrophobia, inability to lay still for the duration of the exam. Already established local recurrence in the prostate is not a contra-indication for study participation.

Intervention: 50 patients who already were referred by their treating physician for PET/CT will receive both an 18F-PSMA-1007 PET-CT (90 minutes post injection) and an 18F-Fluciclovine PET-CT (<15 minutes post injection). Injected dose of the 18F-PSMA-1007 will be 4 MBq/kg ±10%. The injected dose of 18F-Fluciclovine is 370 MBq ±10%.

Analysis: A clinical report is made of both the 18F-PSMA-1007 PET-CT scan and 18F-Fluciclovine PET-CT scan. For further analysis in the study all data will be anonymized, and will be blindly scored by two nuclear medicine physicians. The number of PET-positive lesions (judged to be prostate cancer, of course PET positive lesions referring to different processes like inflammation will not be taken intob account, this is oart of the PET-reading process) per area are separately scored for both tracers. Lesions will be scored on a 5-point scale ranging from most probably benign to most probably malignant. Follow-up data of the patients, to determine the eventual outcome, will be extracted from their medical file. An expert panel will eventually decide which lesions are considered to be metastases using all available follow-up data.

Inclusion Criteria:

• Males ≥ 18 years
• Histologically proven adenocarcinoma of the prostate
• Prior local treatment with curative intent
• Biochemical recurrence with (rising) PSA-levels of 0.2-5.0 ug/L
• Referred by urologist for PET/CT for localization of the recurrence
• PSA level determined <8 weeks before study participation
• Willing to sign informed consent

Exclusion Criteria:

• Contra-indications for PET-CT: claustrophobia or inability to lay still for the duration of the exam.
• Other cancer <2 years prior to biochemical recurrence of prostate cancer

scans will be anonymized for study outcome assessment.