Delayed 18F-FDG PET/CT in Improving Visualization of Brain Tumors in Patients With Glioblastoma

PRIMARY OBJECTIVES: I. To improve the visualization/delineation of glioblastoma lesions using delayed 18F-FDG PET/CT imaging. OUTLINE: Patients receive fludeoxyglucose F-18 intravenously (IV). Patients then undergo a standard of care PET/CT scan at 60 minutes and a second PET/CT scan at 240 minutes after injection. Note: Standard Uptake Value (SUV) is defined for state-of-the art PET/CT scanners as Standardized uptake values = count activity per ml within region of interest (MBq/ml)/\[injected dose (MBq)/body weight (kgx1000)\]