William Reginold1,2, Kevin Sam2, Julien Poublanc2, Joe Fisher3, Adrian Crawley1,2, David J Mikulis4,5. 1. Department of Medical Imaging, University of Toronto, 263 McCaul Street, Toronto, ON, M5T 1W7, Canada. 2. Division of Neuroradiology, Joint Department of Medical Imaging, 3MC-431, Toronto Western Hospital, University Health Network, 399 Bathurst Street, Toronto, ON, M5T 2S8, Canada. 3. Department of Anesthesia, University of Toronto, 600 University Avenue, Toronto, ON, M5G 1X5, Canada. 4. Department of Medical Imaging, University of Toronto, 263 McCaul Street, Toronto, ON, M5T 1W7, Canada. David.Mikulis@uhn.ca. 5. Division of Neuroradiology, Joint Department of Medical Imaging, 3MC-431, Toronto Western Hospital, University Health Network, 399 Bathurst Street, Toronto, ON, M5T 2S8, Canada. David.Mikulis@uhn.ca.
Abstract
PURPOSE: It is unclear how white matter hyperintensities disrupt surrounding white matter tracts. The aim of this tractography study was to determine the spatial relationship between diffusion characteristics along white matter tracts and the distance from white matter hyperintensities. METHODS: Diffusion tensor 3-T MRI scans were acquired in 29 participants with white matter hyperintensities. In each subject, tractography by the fiber assignment by continuous tracking method was used to segment corticospinal tracts. Mean diffusivity, radial diffusivity, axial diffusivity, and fractional anisotropy were measured along corticospinal tracts in relation to white matter hyperintensities. Diffusion characteristics along tracts were correlated with distance from white matter hyperintensities and were also compared between tracts traversing and not traversing white matter hyperintensities. RESULTS: In tracts not traversing through white matter hyperintensities, increasing distance from white matter hyperintensities was associated with decreased mean diffusivity (p = 0.002) and increased fractional anisotropy (p = 0.006). In tracts traversing white matter hyperintensities, compared to tracts not traversing white matter hyperintensites, the mean diffusivity was higher at 6-8 voxels, axial diffusivity higher at 4-8 voxels, and radial diffusivity higher at 7 voxels away from white matter hyperintensities (all p < 0.006). CONCLUSION: White matter hyperintensities are associated with two patterns of altered diffusion characteristics in the surrounding white matter tract network. Diffusion characteristics along white matter tracts improve further away from white matter hyperintensities suggestive of a local penumbra pattern. Also, altered diffusion extends further along tracts traversing white matter hyperintensities suggestive of a Wallerian-type degenerative pattern.
PURPOSE: It is unclear how white matter hyperintensities disrupt surrounding white matter tracts. The aim of this tractography study was to determine the spatial relationship between diffusion characteristics along white matter tracts and the distance from white matter hyperintensities. METHODS: Diffusion tensor 3-T MRI scans were acquired in 29 participants with white matter hyperintensities. In each subject, tractography by the fiber assignment by continuous tracking method was used to segment corticospinal tracts. Mean diffusivity, radial diffusivity, axial diffusivity, and fractional anisotropy were measured along corticospinal tracts in relation to white matter hyperintensities. Diffusion characteristics along tracts were correlated with distance from white matter hyperintensities and were also compared between tracts traversing and not traversing white matter hyperintensities. RESULTS: In tracts not traversing through white matter hyperintensities, increasing distance from white matter hyperintensities was associated with decreased mean diffusivity (p = 0.002) and increased fractional anisotropy (p = 0.006). In tracts traversing white matter hyperintensities, compared to tracts not traversing white matter hyperintensites, the mean diffusivity was higher at 6-8 voxels, axial diffusivity higher at 4-8 voxels, and radial diffusivity higher at 7 voxels away from white matter hyperintensities (all p < 0.006). CONCLUSION: White matter hyperintensities are associated with two patterns of altered diffusion characteristics in the surrounding white matter tract network. Diffusion characteristics along white matter tracts improve further away from white matter hyperintensities suggestive of a local penumbra pattern. Also, altered diffusion extends further along tracts traversing white matter hyperintensities suggestive of a Wallerian-type degenerative pattern.
Entities:
Keywords:
Cerebral small vessel disease; Diffusion tensor imaging; Normal-appearing white matter; Tractography; White matter hyperintensity
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