FDG, MET or CHO? The quest for the optimal PET tracer for glioma imaging continues.

This Practice Point commentary discusses a study by Kato et al. that assessed the usefulness of three PET tracers--(11)C-methionine (MET), (18)F-fluorodeoxyglucose, and (11)C-choline--for the metabolic evaluation of gliomas. The authors measured the ratio of tumor uptake to normal brain uptake (T/N ratio), with the frontal cortex as reference region, and analyzed the correlations between tracer uptake and tumor grade, type, and proliferation activity. Whereas all three tracers showed a similar correlation between the T/N ratio and tumor grade in astrocytic and oligodendroglial tumors, MET proved to be the most user-friendly marker in all gliomas as it enables the straightforward localization of 'hot lesions' and provides outstanding quantitative metabolic parameters. Here we highlight a few methodological issues arising from Kato et al.'s study and, consequently, we urge the PET community to reach a consensus on an objective approach towards the evaluation of PET tracers in the field of neuro-oncology.