Inclusion Criteria:

• Histopathological proven prostate adenocarcinoma.
• Rising PSA after definitive therapy with prostatectomy or radiation therapy (external beam and/or brachytherapy) or prostate cancer ablation.
• Post radical prostatectomy (RP) – with or without radiation.
• PSA greater than or equal to 0.2 ng/mL measured more than 6 weeks after RP.
• > 3 months post-surgery.
• Post-radiation therapy –ASTRO-Phoenix consensus definition.
• May or may not be castrate resistant (list prior therapies; i.e. androgen deprivation therapies).
• Post-prostate cancer tissue ablation.
• In patients post-ablation for primary prostate cancer treatment, PSA greater than or equal to 0.2 ng/mL measured more than 6 weeks after ablation.
• > 3 months post-prostate bed ablation.
• In patients with intact prostate, per ASTRO-Phoenix consensus definition.
• Karnofsky performance status of 50 (or ECOG/WHO equivalent).
• CT as part of the PET study or performed within 30 days of PSMA PET.
• Age > 18 years old.
• Ability to understand a written informed consent document, and the willingness to sign it.
• Total testosterone test measured within 30 days of PSMA PET.

Exclusion Criteria:

• Undergoing (or within 4 months) investigational therapy for prostate cancer.
• Other ongoing (or within 4 months) treatments for prostate cancer including radiation therapy or chemotherapy.
• Unable to lie flat, still or tolerate a PET scan.
• Prior history of any other malignancy within the last 2 years, other than skin basal cell or cutaneous superficial squamous cell carcinoma that has not metastasized.
• Contraindication to furosemide administration including prior allergy or adverse reaction to furosemide or sulfa drugs.
  • Note: This exclusion criteria can be removed if Furosemide is omitted as part of the PET imaging protocol if a second-generation scatter correction is available for the used PET device.
• Absence of PSA and total testosterone tests within 30 days.