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.