Interestingly, IDH-mutant, 1p19q non-codeleted astrocytomas, which are frequently located in the frontal and temporal lobes, are characterized by “T2-FLAIR mismatch”, namely a different appearance of the lesion between the two sequences characterized by T2 hyperintensity and incomplete attenuation on FLAIR, defined by a core inhomogeneous hypointensity surrounded by a peripheral rim of hyperintensity (Figure 1). The gene discussed is IDH1; the disease is astrocytoma (excluding glioblastoma).