Understanding metabolic aberrations in IDH-mutated gliomas requires xenograft models growing in a relevant tissue microenvironment and resembling its human genetic counterparts. We performed in vivo 1H MRSI of human-derived oligodendroglioma xenograft models to map lactate and total choline concentrations. Lactate levels were significantly lower and total choline higher in mutated tumor tissue compared to non-tumor brain in the same animal, or to its wild-type counterpart model. This outcome was correlated with expression levels of enzymes and transporters in both lactate- and phospholipid-related metabolic pathways. The findings point to a metabolic reprogramming of aerobic glycolysis and lipid synthesis by the IDH1 mutation.