NI-02 THE ASSOCIATION BETWEEN (11)C-METHIONINE UPTAKE, IDH GENE MUTATION, AND MGMT PROMOTER METHYLATION IN PATIENTS WITH GRADE II AND III GLIOMAS

AIM: We evaluated the association between (11)C-methionine positron emission tomography ((11)C-methionine PET) findings, isocitrate dehydrogenase (IDH) gene mutation, and O(6)-methylguanine-DNA methyltransferase (MGMT) promoter methylation in patients with grade II and III gliomas. MATERIALS AND METHODS: Data were collected from 40 patients with grade II and III gliomas who underwent both magnetic resonance imaging (MRI) and (11)C-methionine positron emission tomography (PET) as part of their pre-surgical examination. We examined IDH mutation through DNA sequencing, and MGMT promoter methylation through quantitative methylation-specific polymerase chain reaction (PCR). RESULTS: A threshold of MGMT promoter methylation of 1.0% was significantly associated with tumor/normal tissue (T/N) ratio. The T/N ratio in samples with MGMT promoter methylation ≥1.0% was higher than that in samples with MGMT promoter methylation <1.0%, and the difference was statistically significant (p = 0.011). Reliable prediction of MGMT promoter methylation (<1.0% vs ≥1.0%) was possible using the T/N ratio under the receiver operator characteristic (ROC) curve with a sensitivity and specificity of 75% each (cut-off value = 1.6) (p = 0.0226, AUC = 0.76172). Conversely, the T/N ratio had no association with IDH mutation (p = 0.6). The ROC curve revealed no reliable prediction of IDH mutation using the T/N ratio (p = 0.606, AUC = 0.60577). CONCLUSION: (11)C-methionine PET parameters can predict MGMT promoter methylation but not IDH mutation status. (11)C-methionine uptake may have limited potential to reflect DNA methylation processes in grade II and III gliomas.