Alterations in Microstructure and Local Fiber Orientation of White Matter Are Associated with Outcome after Mild Traumatic Brain Injury

Mehrbod Mohammadian*, Timo Roine, Jussi Hirvonen, Timo Kurki, Jussi P. Posti, Ari J. Katila, Riikka S. K. Takala, Jussi Tallus, Henna-Riikka Maanpaa, Janek Frantzen, Peter J. Hutchinson, Virginia F. Newcombe, David K. Menon, Olli Tenovuo

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

Abstract

Mild traumatic brain injury (mTBI) can have long-lasting consequences. We investigated white matter (WM) alterations at 6-12 months following mTBI using diffusion tensor imaging (DTI) and assessed if the alterations associate with outcome. Eighty-five patients with mTBI underwent diffusion-weighted magnetic resonance imaging (MRI) on average 8 months post-injury and patients' outcome was assessed at the time of imaging using the Glasgow Outcome Scale-Extended (GOS-E). Additionally, 30 age-matched patients with extracranial orthopedic injuries were used as control subjects. Voxel-wise analysis of the data was performed using a tract-based spatial statistics (TBSS) approach and differences in microstructural metrics between groups were investigated. Further, the susceptibility of the abnormalities to specific fiber orientations was investigated by analyzing the first eigenvector of the diffusion tensor in the voxels with significant differences. We found significantly lower fractional anisotropy (FA) and higher mean diffusivity (MD) and radial diffusivity (RD) in patients with mTBI compared with control subjects, whereas no significant differences were observed in axial diffusivity (AD) between the groups. The differences were present bilaterally in several WM regions and correlated with outcome. Moreover, multiple clusters were found in the principal fiber orientations of the significant voxels in anisotropy, and similar orientation patterns were found for the diffusivity metrics. These directional clusters correlated with patients' functional outcome. Our study showed that mTBI is associated with WM changes at the chronic stage and these alterations occur in several WM regions. In addition, several significant clusters of WM alterations in specific fiber orientations were found and these clusters were associated with outcome.

Original languageEnglish
Number of pages8
JournalJOURNAL OF NEUROTRAUMA
DOIs
Publication statusPublished - 17 Aug 2020
MoE publication typeA1 Journal article-refereed

Keywords

  • diffusion tensor imaging
  • mild traumatic brain injury
  • outcome
  • tract-based spatial statistics
  • DIFFUSE AXONAL INJURY
  • CONSTRAINED SPHERICAL DECONVOLUTION
  • TENSOR IMAGING DETECTS
  • SPATIAL STATISTICS
  • CORPUS-CALLOSUM
  • WATER DIFFUSION
  • DTI
  • MRI
  • ABNORMALITIES
  • DYSMYELINATION

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