Rationale: Novel radiopharmaceuticals for positron emission tomography (PET) are evaluated for the diagnosis of biochemically recurrent prostate cancer (BCR PC). Here, we compare the gastrin releasing peptide receptors (GRPR) – targeting 68Ga-RM2 with the prostate specific membrane antigen (PSMA) – targeting 68Ga-PSMA11 and 18F-DCFPyL.