PET with <sup>18</sup>F-GE-180 and <sup>18</sup>F-FET provides differing imaging information in HGG dependent on the IDH-mutational status, with diverging spatial overlap and vast exceedance of contrast-enhancement in MRI.
Most IDH-wildtype tumors showing histopathological and radiological features of low-grade diffuse astrocytoma exhibit molecular and clinical features of high-grade glioma and may represent an early stage of primary glioblastoma.
Association Between IDH1 and IDH2 Mutations and Preoperative Seizures in Patients with Low-Grade Versus High-Grade Glioma: A Systematic Review and Meta-Analysis.
CMRO<sub>2</sub> showed the highest diagnostic performance for IDH gene mutation detection in low-grade glioma (AUC, 0.818) and MTI in high-grade glioma (AUC, 0.854) and for all WHO grades (AUC, 0.899) among all biomarkers.
Recently, mutations of the ATRX gene have been found in various subtypes and grades of gliomas and were shown to refine the prognosis of malignant gliomas in combination with IDH and 1p/19q status.
These results suggest that miR-183 upregulation in malignant gliomas induces HIF-1α expression by targeting IDH2 and may play a role in glioma biology.
Different molecular biomarkers were identified by genetic studies and some of these are used in neuro-oncology for the evaluation of glioma patients, in particular combined deletions of the chromosome arms 1p and 19q in oligodendroglial tumors, methylation status of the O-6 methylguanine- DNA methyltransferase gene promoter and alterations in the epidermal growth factor receptor pathway in adult malignant gliomas, isocitrate dehydrogenase 1 (IDH1) and IDH2 gene mutations in diffuse gliomas, as well as BRAF status in pilocytic astrocytomas.