Can Conventional MRI Features Predict H3K27M Mutation Status of Diffuse Midline Gliomas?

Abstract Purpose Pre-surgical prediction of H3K27M mutation in diffuse midline gliomas (DMG) on MRI is desirable. The purpose of the study is to elaborate conventional MRI (cMRI) of H3K27M-mutant DMGs and identify features that could discriminate them from WT (wild type)-DMGs.Methods cMRI features of 123 patients with DMG were evaluated conforming to the institutional research protocols. Multimodality MRI was performed on 1.5 or 3.0 Tesla MR Scanners with imaging protocol including T1w, T2w, FLAIR, diffusion-weighted, susceptibility-weighted and post- contrast T1w sequences. Pertinent cMRI features were annotated along the lines of Visually AcceSAble Rembrandt Images (VASARI) features and Intra Tumoral Susceptibility Signal score (ITSS) were evaluated. R software was used for statistical analysis.Results Sixty-one DMGs were H3K27M-mutant (mutant DMGs). The patients in the H3K27M-mutant DMG group were younger compared to the WT-DMG group (WT DMGs) (mean age 24.13+13.13 years vs. 35.79+18.74 years) (P= 0.016). The two groups differed on 5 cMRI features– i) enhancement quality (P=0.032), ii) thickness of enhancing margin (P=0.05), iii) proportion of edema (P=0.002), iv) definition of non-contrast enhancing tumor (NCET) margin (P=0.001) and v) cortical invasion (P=0.037). The mutant DMGs showed greater enhancement and greater thickness of enhancing margin while the WT DMGs exhibited significantly larger edema proportion with poorly defined NCET margins and cortical invasion. ITSS was not significantly different among the groups. Conclusion cMRI features like enhancement quality, thickness of the enhancing margin, proportion of edema, definition of NCET margin and cortical invasion can discriminate between the H3K27M-mutant and WT DMGs.