Figure 7.

Comparison of reconstructions of the corticospinal tract (CST) depending on the algorithm chosen for tractography in patients with high radial extent in the tumor-affected hemisphere. This figure shows reconstructions of the CST using diffusion tensor imaging (DTI)-based tractography, constrained spherical deconvolution (CSD)-based tractography, and multi-level fiber tracking (MLFT) within the tumor-affected and unaffected hemispheres in the subset of the three patients that were identified as outliers regarding radial extent within affected hemispheres (considering a 2σ threshold). The tumor core is shown as a red volume, the hyperintense zone in fluid attenuated inversion recovery (FLAIR) sequences is shown as a yellow volume. These patients were all characterized by extensive mass effect that caused deformation of the CST bundle within the tumor-affected hemisphere as well as, to a lesser extent, within the unaffected hemisphere with considerable midline shift (red arrow in coronal contrast-enhanced T1-weighted and coronal FLAIR images). In all cases, fanning is considerably improved particularly in the tumor-affected hemispheres when using the MLFT algorithm, with only few fibers with acute angles being displayed adjacent to the tumor masses when using DTI-based tractography.