Utility of three-dimensional anisotropy contrast magnetic resonance axonography for determining condition of the pyramidal tract in glioblastoma patients with hemiparesis

Background and purpose: Three-dimensional anisotropy contrast magnetic resonance axonography (3DAC) is a technique for diffusion weighted magnetic resonance imaging (DWI) that offers reliable visualization of the pyramidal tracts. This study evaluated condition of the pyramidal tract using 3DAC in glioblastoma patients with hemiparesis. Methods: In 18 glioblastoma patients before surgery, 3DAC findings of the pyramidal tract responsible for hemiparesis were compared with finding from proton density-weighted imaging (PDWI). To estimate extent of pyramidal tract destruction, fractional anisotropy (FA) values using diffusion tensor magnetic resonance imaging were examined for both the responsible and non-pathological pyramidal tracts. Results: In all five patients for whom PDWI indicated no hyperintense foci in the responsible pyramidal tract, 3DAC demonstrated no change in color. When PDWI revealed hyperintense foci, 3DAC showed two types of findings: no color change (five patients); or obscured dark area (six patients). When 3DAC showed a dark area, mean FA value in the responsible tract was significantly lower than that for the non-pathological tract. Conclusion: When PDWI indicates hyperintense foci on the pyramidal tract, 3DAC allows prediction of pyramidal tract condition, such as large tumor invasion.