This study aims to investigate the diagnostic value of FAPI PET/CT, relative to standard-of-care imaging using PSMA PET/CT, in staging of newly diagnosed PCa. FAPI PET/CT will be visually and quantitatively correlated to PSMA PET/CT resulting in detection rates and target-to-background ratios. If available, histopathology of resected specimens will serve as reference test for operated patients in order to determine diagnostic accuracy. All outcomes are descriptive and serve as pilot for a potential subsequent larger prospective diagnostic study.

Inclusion Criteria:

• Male, aged ≥ 18 years;
• WHO performance status 0, 1 or 2;
• Written informed consent;
• Biopsy-proven newly diagnosed PCa;
• International Society of Urological Pathology (ISUP) grade group (GG) ≥ 3 and/or PSA ≥ 20 ng/ml and/or ≥cT3a.

If all of the criteria above are met, a subject must also meet all of the following subgroup specific criteria:

Group 1 (n=15):

- PSMA PET/CT with PSMA-avid primary tumor with PSMA-avid loco-regional and/or distant metastases.

Group 2 (n=15):

• PSMA PET/CT with PSMA-avid primary tumor with no PSMA-avid loco-regional or distant metastases;
• Increased risk of nodal metastases according to the Briganti 2019 nomogram (Briganti ≥40%) [22];
• Scheduled for (laparoscopic) prostatectomy including ePLND.

Exclusion Criteria:

• Known second malignant disease that may complicate image interpretation.
• Inability to cooperate with the scan process: inability to lie relatively still and in supine for 30-60 minutes or patient body habitus above scanner dimensions.

All scans will be reviewed by two senior nuclear medicine physicians (NWZ-Alkmaar and/or NCI-AVL), separately and blinded to any clinical information. If a consensus is not reached, a third observer is included.