PRIMARY OBJECTIVE:~I. To assess the optimal fludeoxyglucose F-18 (fluorodeoxyglucose) positron emission tomography (FDG PET) imaging time post radiotracer administration that maximizes separation of activity between lesion and non-lesional parenchyma (measured as lesion/background [L/B] ratio) in patients with brain metastasis.~SECONDARY OBJECTIVE:~I. To identify genotypic factors in FDG tumor metabolism derived from metrics, including maximum standard uptake value (SUVmax), mean standard uptake value (SUVmean), total lesion glycolysis (TLG), mean tumor volume (MTV), and L/B ratio.~EXPLORATORY OBJECTIVES:~I. To identify patterns of metabolism derived from metrics, such as SUVmax, SUVmean, TLG, MTV, and L/B ratio, and magnetic resonance imaging metrics, such as regional perfusion abnormalities, apparent diffusion coefficient values, fractional diffusivity measures, and magnetic resonance spectroscopic finding.~II. To identify if post treatment changes in lesion metabolism from baseline correlate with treatment success.~OUTLINE:~Patients receive fludeoxyglucose F-18 intravenously (IV) over approximately 1 minute and undergo a PET/MRI scan over 70 minutes. Within 5 hours of receiving fludeoxyglucose F-18, patients undergo a repeat PET/MRI scan over 30 minutes. Scans take place within 2 weeks before scheduled surgery and within 4-6 weeks after radiation treatment.
This phase IV trial studies how well delaying positron emission tomography (PET)/magnetic resonance imaging (MRI) scan after injection of fluorodeoxyglucose (FDG) can improve the imaging of patients with cancer that has spread to brain (brain metastases). FDG is a type of imaging agent that doctors use to help see the images on a scan more clearly. Delaying PET/MRI scan after injecting FDG may improve how well doctors can tell the difference between healthy and unhealthy tissue.