Assessment the Impact of IDH Mutation Status on MRI Assessments of White Matter Integrity in Glioma Patients: Insights From Peak Width of Skeletonized Mean Diffusivity and Free Water Metrics

Abstract

BackgroundGliomas are highly invasive brain tumors that evade accurate geographic assessment by conventional MRI due to microscopic invasion along white matter (WM) tracts. Advanced diffusion MRI techniques are needed to assess occult WM involvement.PurposeTo evaluate peak width of skeletonized mean diffusivity (PSMD) and peak width of skeletonized free water (PSFW), and axonal water fraction (AWF) for assessing glioma‐induced alterations in normal‐appearing WM and their relationship with isocitrate dehydrogenase 1 (IDH1) mutation.Study TypeRetrospective.PopulationOne hundred five glioma patients (46 ± 13 years), 53 healthy controls (HCs) (46 ± 9 years).Field Strength/Sequence3.0 T, T1WI, T1‐CE, T2WI, T2FLAIR, and DKI.AssessmentPSMD and PSFW were compared between lesion and contralateral sides in glioma patients and between patients and HCs. The associations between these metrics and clinical variables, including IDH1 mutation, was assessed. Corpus callosum (CC) injury, quantified by the AWF, was evaluated for its mediated effect of IDH1 mutation on contralesional PSMD and PSFW.Statistical TestsPaired‐t tests, ANCOVA, univariate and multivariate linear regression, and mediation analysis with significance set at P < 0.05.ResultsContralateral PSMD and PSFW were significantly higher in left‐sided gliomas (PSMD: 0.206 ± 0.027 vs. 0.193 ± 0.023; PSFW: 0.119 ± 0.019 vs. 0.106 ± 0.020) than in HCs, with similar increases in right‐sided gliomas (PSMD: 0.219 ± 0.036 vs. 0.195 ± 0.023; PSFW: 0.129 ± 0.031 vs. 0.109 ± 0.020). IDH1 wild‐type gliomas were associated with higher contralateral PSMD and PSFW (β = −0.302 and −0.412). AWF of CC mediated the impact of IDH1 mutations on contralesional PSMD and PSFW (mediated proportion: 42.7% and 53.7%).Data ConclusionPSMD and PSFW are effective biomarkers for assessing WM integrity in gliomas, significantly associated with IDH1 mutation status. AWF of CC mediates the relationship between IDH1 mutation and contralesional PSMD and PSFW.Evidence Level4Technical EfficacyStage 2