Figure 3:

Genomic and radiogenomic landscape of diffuse gliomas. Diffuse gliomas are fundamentally differentiated according to presence of IDH mutation. IDH mutant gliomas are typically lower grade (World Health Organization [WHO] grades II–III) but can sometimes be glioblastoma (GBM) (WHO grade IV), in which case they usually arise from a lower-grade astrocytoma. IDH mutant gliomas are subdivided according to presence of 1p19q codeletion, which defines an oligodendroglioma, and are associated with “poorly circumscribed” margins. The 1p19q non-codeleted tumors are characterized by “circumscribed” margins and exhibit the “T2–fluid-attenuated inversion recovery (FLAIR) mismatch” pattern. IDH wild-type gliomas are typically glioblastomas but may sometimes be a lower-grade astrocytoma or oligodendroglioma not otherwise specified (NOS). Epidermal growth factor receptor (EGFR) mutations and O⁶-methylguanine-DNA-methyltransferase (MGMT ) methylation status are important molecular and prognostic markers. EGFR mutant gliomas are associated with increased cerebral blood volume (CBV ). Methylated MGMT gliomas are associated with “masslike” T2-FLAIR signal intensity abnormality and heterogeneous and/or nodular enhancement pattern, whereas unmethylated MGMT gliomas are associated with “infiltrative” T2-FLAIR signal intensity abnormality and thick enhancement pattern with central necrosis. Background shading represents overall prognosis (green = best, yellow = intermediate, red = worst). wt = wild-type.