With the IDH1 R132 (Arginine 132) mutation leading to an accumulation of 2 hydroxyglutarate, magnetic resonance spectroscopy (MRS) allows the measurement of this oncometabolite in vivo (49, 50), which has been applied for non-invasively predicting IDH-mutation status in glioma patients (51) and for investigating remote glioma cell infiltration in vivo (52–54). Here, IDH1 is linked to central nervous system cancer.