Inclusion Criteria:  Patients with known biochemical recurrence of a histologically confirmed prostate cancer post radical prostatectomy, defined as two consecutive prostate specific antigen (PSA) values > 0.2 ng/ml: Post prostatectomy: Patients > 18 y/o PSA measured within ± 4 weeks of the first PSMA-PET/CT Patients providing written informed consent No change in PC treatment in the period between the first and second scans  Exclusion Criteria:  Patients receiving androgen deprivation therapy (ADT) within 6 months prior to the PSMA-PET/CT Patients with contraindication to diuresis with 20mg Furosemide Patients with renal dialysis or relevant renal impairment (eGFR < 35 ml/min) Inability to provide written informed consent Inability to schedule and attend two consecutive PET examinations Patients undergoing active treatment for a second non-prostatic malignancy at the time of the first scan. Known sensitivity or allergy to PSMA-ligands or one of the components of the radiotracer solutions used.