CLINICAL STUDY Glioma infiltration of the corpus callosum: early signs detected by DTI

Abstract The most frequent primary brain tumors, ana-plastic astrocytomas (AA) and glioblastomas (GBM): tend to invasion of the surrounding brain. Histopathological studies found malignant cells in macroscopically unsuspi-cious brain parenchyma remote from the primary tumor, even affecting the contralateral hemisphere. In early stages, diffuse interneural infiltration with changes of the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) is suspected. The purpose of this study was to investigate the value of DTI as a possible instrument of depicting evidence of tumor invasion into the corpus callosum (CC). Preoperatively, 31 patients with high-grade brain tumors (8 AA and 23 GBM) were examined by MRI at 3 T, applying a high-resolution diffusion tensor imaging (DTI) sequence. ADC- and FA-values were analyzed in the tumor-associ-ated area of the CC as identified by fiber tracking, and were compared to matched healthy controls. In (MR-)morpho-logically normal appearing CC the ADC values were ele-vated in the tumor patients (n = 22; 0.978 9 10-3 mm2/s) compared to matched controls (0.917 9 10-3 mm2/s, p \ 0.05), and the corresponding relative FA was reduced (rFA: 88 %, p \ 0.01). The effect was pronounced in case of affection of the CC visible on MRI (n = 9; 0.978 9 10-3 mm2/s, p \ 0.05; rFA: 72 % , p \ 0.01). Changes in diffusivity and anisotropy in the CC can be interpreted as an indicator of tumor spread into the con-tralateral hemisphere not visible on conventional MRI