A critical review of PET tracers used for brain tumor imaging

Because enhancement on computed tomography (CT) and MR reflects blood-brain barrier (BBB) changes, molecular imaging with PET-based techniques is needed to assess brain tumor activity, especially in tumors with intact or partially intact BBB. 18F-fluorodeoxyglucose (FDG)-PET has been validated in tumor detection/delineation, recurrence, and prognostication. Although FDG remains the most widely used PET tracer in the evaluation of brain tumors, various other tracers, including amino acid indicators, have been studied extensively. Breakdown of the BBB plays a major role in visualizing brain tumors by radiolabeled amino acid tracers; therefore, this approach is suboptimal for assessing disease activity beyond CT and MR