FDG PET-MRI for the Diagnosis of Spinal Cord Lesions

Primary Objectives: --To identify the optimal imaging time point using F18-FDG positron emission tomography (PET) that gives the best lesion conspicuity as defined by the best lesion to background (L/B) ratio when evaluating spinal cord lesions of unknown etiology. Exploratory Objectives: * To identify malignancy specific factors in F18-FDG metabolism derived from metrics such as maximum standard uptake value (SUVmax), mean standard uptake value (SUVmean), total lesion glycolysis (TLG), metabolic tumor volume (MTV) and L/B ratio. * To identify patterns of metabolism derived from metrics such as SUVmax, SUVmean, TLG, MTV, L/B ratio and magnetic resonance imaging metrics such as regional perfusion abnormalities, apparent diffusion coefficient values and mean diffusivity measures. OUTLINE: Patients receive fludeoxyglucose F-18 intravenously (IV) over 1 minutes and then undergo PET-magnetic resonance imaging (MRI) over 15-60 minutes at 60, 300, and 480 minutes after fludeoxyglucose F-18 injection in the absence of unacceptable toxicity.