18F-Fluciclovine PET for Brain Metastases after SRS

Inclusion Criteria: * Diagnosis of cancer with radiographic finding of brain metastasis * Any number of brain metastasis, with all lesions ≤ 2 cm in maximum dimension * Planned treatment with SRS as per the treating physician team * Eastern Cooperative Oncology Group (ECOG) performance status 0-2 * Individuals of reproductive potential need to employ two highly effective and acceptable forms of contraception for at least 4 weeks prior to screening and agree to use such a method during study participation up to an additional 1 week following the last 18F-fluciclovine PET Exclusion Criteria: * Prior anaphylactic reaction to 18F-fluciclovine * Radiographic evidence of leptomeningeal disease * Prior whole-brain radiation therapy * Inability to undergo MRI (e.g., due to safety reasons, such as presence of a pacemaker) * Pregnant or positive serum pregnancy test within 14 days of registration * Individuals expecting to be breastfeeding at the time of 18F-fluciclovine and unwilling to stop breast-feeding for 24 hours. Temporary cessation of breastfeeding for 24 hours after the time of imaging is allowed. * Major medical illness or psychiatric/cognitive impairments, which in the investigator's opinion, will prevent completion of protocol and/or preclude informed consent\* * A legally authorized representative (LAR) may consent on a potential participant's behalf in the case of cognitive impairment, if in the investigator's opinion, that impairment would not prevent completion of the protocol.