Evaluating Fluciclovine PET in Patients With Biochemical Recurrence of Prostate Cancer and a Negative PSMA PET

Inclusion Criteria: * Age \>= 18 years. * Participant or legally authorized representative (LAR) must provide written informed consent before any study-specific procedures or interventions are performed. * Patients with suspected BCR of prostate cancer after initial treatment, and a negative or equivocal PSMA PET, regardless of the findings on conventional imaging. Initial treatment may include prostatectomy and/or radiation therapy. * PSA of 0.2 ng/mL or higher within 45 days of the scan. Exclusion Criteria: * Uncontrolled serious infection. * Intercurrent illness or condition that would limit compliance with study requirements. * Patients who have started any cancer treatment (systemic or radiation therapy) or who have started any supplements or herbal medications intended to treat cancer between the PSMA PET and Axumin PET/CT scans.