IDH status shapes glioma oncotopy: voxel-wise mapping of 644 adult diffuse gliomas

The aim of this study was to characterize the anatomical and imaging features of adult-type diffuse gliomas across histomolecular subtypes.

Clinical 3-Tesla brain MRI images from 644 patients with pathologically confirmed adult-diffuse glioma before treatment was retrospectively evaluated: 527 IDH-wildtype glioblastoma, 71 astrocytoma, and 46 oligodendroglioma. Pre- and post-contrast T1-weighted, T2-weighted and FLAIR sequences were part of the MRI protocol. Contrast-enhancing tumors and non-enhancing lesions (NEL) were automatically segmented using HD-GLIO. We used a voxel-wise Fisher-exact-test followed by random-permutation (ADIFFI) to identify regions with higher occurrence of tumor associated with IDH-mutation status or 1p/19q-codeletion status. Mann-Whitney-U-test was used to compare signal intensities in CET and NEL across the three different subtypes of adult-diffuse glioma investigated here.

We observed a significant correlation of IDH-mutant gliomas with a predominance in the frontal lobe adjacent to the rostral extension of the lateral ventricles. IDH-wildtype tumors had larger NEL volumes than IDH-mutant gliomas (p < 0.0001). Signal intensity analysis demonstrated consistently lower T1w and T1-CE values and higher T2w and FLAIR values in IDH-mutant gliomas (all p < 0.0001). Oligodendrogliomas showed higher signal intensity on T1-CE images compared to astrocytomas (p = 0.035).

We analyzed a large radio-genomic patient cohort consisting of glioblastoma, astrocytoma and oligodendroglioma. Our findings are in line with previously analyzed smaller patient cohorts. Our findings underline the importance of the IDH-mutation for determining tumor location and potentially point to a cell of origin along the rostral extension of the lateral ventricles.