White matter tract involvement in brain tumors: a diffusion tensor imaging analysis

Background: Characterization of WM alteration using MR imaging is important in the pre- and intraoperative assessment of brain tumors. This study characterizes the extent and severity of WM tract alterations near brain tumors using DTI in an effort to determine preoperative viability or resectability of the adjacent WM tracts. Fractional anisotropy is an important DTI-derived metric of MR imaging. Methods: Twenty-one patients underwent MR DTI. Eighty-six WM tracts composed of 43 WM lesions paired with 43 contralateral WM hemispheric controls were categorized using FA. Neuroradiologists categorized the WM tracts as edematous, displaced, disrupted, or infiltrated with tumor using directionally encoded color maps. A mixed model analysis was used to compare FA. Results: Of the lesioned tracts, 5 were scored as edema, 9 as infiltration, 18 as displacement, and 11 as disruption. A significant Delta FA% was found between the lesioned and contralateral hemispheres only in WM disruption (P=.0056). Both edema FA and disruption FA are significantly less than displacement FA (P<.05). The FA change (Delta FA% = [FA(lesion) - FA(normal)]/FA(normal) x 100%) on the lesioned side was calculated. A Delta FA% less than -30% is likely to be associated with WM disruption. A positive Delta FA% is likely to be associated with edema or displacement, and a Delta FA% between 0% and -30% is likely to be associated with WM displacement or infiltration. Conclusions: Quantitative analysis of DTI data may provide insight as to whether WM tracts are salvageable preoperatively. (C) 2009 Elsevier Inc. All rights reserved.