PURPOSE: This prospective, multicentre, intra-patient comparator study assessed urinary radioactivity, and patient-level and region-level detection rates (DR) with PSMA-PET radiopharmaceuticals, 18F-piflufolastat (18F-DCFPyL) and 18F-flotufolastat (18F-rhPSMA-7.3) in patients with biochemical recurrence (BCR) of prostate cancer to evaluate the hypothesis that lower urinary radioactivity is observed with 18F-flotufolastat. Here, FOLH1 is linked to Familial prostate cancer.