4. PET/CT Scans will be performed with or without oral and IV contrast. All investigational scans will be read by at least one board-certified nuclear medicine physician with established expertise in PET/CT of at least 5 years' experience. Fifteen minutes after injection of 11C-Sodium Acetate, the investigators will acquire a scan. Emission images will be acquired for 3-5min/bed position. Intravenous and oral contrast will be given for the CT portion of the study.