The association between 11C-methionine uptake, IDH gene mutation, and MGMT promoter methylation in patients with grade II and III gliomas

Abstract

To evaluate the association between 11C-methionine positron-emission tomography (11C-methionine PET) findings, isocitrate dehydrogenase (IDH) gene mutation, and O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation in patients with grade II and III gliomas. Data were collected from 40 patients with grade II and III gliomas who underwent both magnetic resonance imaging (MRI) and 11C-methionine PET as part of their pre-surgical examination. IDH mutation was examined via DNA sequencing, and MGMT promoter methylation via quantitative methylation-specific polymerase chain reaction (PCR). A threshold of MGMT promoter methylation of 1% was significantly associated with tumour/normal tissue (T/N) ratio. The T/N ratio in samples with MGMT promoter methylation ≥1% was higher than that in samples with MGMT promoter methylation <1%, and the difference was statistically significant (p=0.011). Reliable prediction of MGMT promoter methylation (<1% versus ≥1%) 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, area under the ROC curve [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). 11C-methionine PET parameters can predict MGMT promoter methylation but not IDH mutation status. 11C-methionine uptake may have limited potential to reflect DNA methylation processes in grade II and III gliomas.