How to differentiate tumor recurrence from radiation necrosis in the brain using an FDG PET scan?
Brain tumors, like other cancers, are typically hypermetabolic. While it is sometimes difficult to detect primary brain tumors from underlying cortical metabolism, after treatment with surgery and/or radiation therapy it becomes much easier to detect recurrent tumor. Thus, on an FDG PET scan, tumor recurrence appears as a hypermetabolic focus whereas radiation or other treatment effects appear as an area of hypometabolism
