18F-Fluciclovine PET/CT in Multiple Myeloma

* INCLUSION CRITERIA: * Participants must have a documented diagnosis of MM defined by the IMWG Criteria. Participants at diagnosis must have had a serum M-protein \>= 3 g/dL and/or bone marrow plasma cells \>= 10% and at least one of the following: * Anemia: Hemoglobin \<=10 g/dL, or * Renal Failure: serum creatinine \>= 2.0 mg/dL, or * Hypercalcemia: Ca \>= 10.5 mg/dL, or * Lytic bone lesions on X-ray, CT, or PET/CT, or * \>= 2 focal lesions on spinal MRI, or * \>= 60% bone marrow plasma cells, or * Involved/un-involved serum free light chain ration \>= 100 * Participants must have measurable disease defined by any one of the following: * Monoclonal bone marrow plasma cells \> 5% * Serum monoclonal protein \>= 0.2 g/dl * Urine monoclonal protein \> 200 mg/24 hr * Serum immunoglobulin free light chain \> 10 mg/dL AND abnormal kappa/lambda ratio * A measurable lesion on PET/CT or MRI * Participants fit criteria for one of the following categories: * Newly diagnosed multiple myeloma (NDMM) * Relapsed and/or refractory multiple myeloma (RRMM) with at least 1 prior line of therapy * Age \>=18 years. * ECOG performance status \<= 2 * Negative serum or urine pregnancy test at screening for WOCBP. * Women of child-bearing potential and men must agree to use effective contraception (hormonal or barrier method of birth control; abstinence) 24 hours prior to and for the 24 hours after each 18F-fluciclovine administration. * Ability of subject to understand and the willingness to sign a written informed consent document. EXCLUSION CRITERIA: * History of allergic reactions attributed to compounds of similar chemical or biologic composition to 18F-FDG * History of allergic reactions attributed to compounds of similar chemical or biologic composition to 18F-fluciclovine or other similar agents. * Subjects with severe claustrophobia unresponsive to oral anxiolytics or unwilling to take them. * Uncontrolled intercurrent illness including, psychiatric illness/social situations that would limit compliance with study requirements. * Because there is an unknown but potential risk for adverse events in nursing infants secondary to treatment of the mother with 18F-fluciclovine, breastfeeding should be discontinued if the mother is treated with 18F-fluciclovine until 3 days after 18F-fluciclovine.