IDH2 and brain glioma: This is why the ability to detect 2HG makes MRSI a very important diagnostic tool.18,31 In previous studies, the accumulation of 2HG in brain gliomas as detected on MRSI has been correlated with mutations in IDH118,31 and IDH2. A representative example of a patient with mutant IDH tumor showing the positive 2HG peak is shown in Figure 1.