Assess Use of 18F-Fluciclovine for Patients With Large Brain Metastases Treated With Staged Stereotactic Radiosurgery

Patients will receive a standard 5 millicuries dose of 18F-fluciclovine intravenously as a bolus injection. They will be required to fast for at least four hours prior to 18F-fluciclovine injection. Patients will be positioned for PET/CT brain imaging and will be injected with 18F-fluciclovine immediately prior to PET data acquisition. PET data will be collected in list mode up to 25 minutes post-injection. PET images will be reconstructed in two ways: as a standard static image of data acquired between 10 to 20 minutes post-injection, and as a dynamic series of four 5-minute frames between 5 to 25 minutes post-injection to allow for motion assessment and correction and time-dependent observations.