WASHINGTON -- The FDA approved the radioactive diagnostic agent fluciclovine (F-18, Axumin) for use with positron emission tomography (PET) to detect recurrent prostate cancer.

A synthetic amino acid, F-18 received approval for use to confirm suspected recurrence in men with treated prostate cancer and rising PSA levels.

"Imaging tests are not able to determine the location of the recurrent prostate cancer when the PSA is at very low levels," Libero Marzella, MD, PhD, director of the FDA's Division of Medical Imaging Products, said in a statement. "Axumin is shown to provide another accurate imaging approach for these patients."

The safety and efficacy of F-18 was evaluated in two trials involving men with treated prostate cancer and elevated PSA levels (biochemical recurrence or relapse). In one study, investigators on site compared F-18 imaging results with pathology findings for 105 men. Independent radiologists then performed the same comparison.

In the second study, radiologists evaluated agreement between F-18 imaging results and those obtained with C-11 choline, another FDA-approved imaging agent approved for use with PET. The study involved 96 men with treated prostate cancer and a median PSA level of 1.44 ng/mL.

Results with both imaging modalities were evaluated on site by radiologists and by independent radiologists blinded to the on-site results. According to the FDA, independent assessment showed the results with the two imaging agents "were generally consistent with one another" and confirmed the on-site assessments.

The most commonly reported adverse events were injection-site pain, redness, and a metallic taste in patients who receive injections of the radioactive agent.

The FDA statement noted that imaging errors can occur with F-18 and that a negative result does not rule out the possibility of prostate cancer recurrence and that positive tests can occur in the absence of prostate cancer.

F-18 is marketed by Blue Earth Diagnostics of Oxford, England.