American Journal of Neuroradiology 2008;29:514.
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American Journal of Neuroradiology
DOI 10.3174/ajnr.A0856
BRAIN
White Matter Abnormalities in Mild Traumatic Brain Injury: A Diffusion Tensor Imaging Study
From the Department of Neuroradiology (D.R.R., F.T., J.C., P.L., D.D.), Centre Hospitalo-Universitaire de Bicêtre, Bicêtre, France; and Institut National de Recherche en Informatique et Automatique (P.F.), Sophia Antipolis Cedex, France.
Please address correspondence to Denis Ducreux, Department of Neuroradiology, CHU de Bicêtre, 78 rue du Général Leclerc, 94270 Le Kremlin Bicêtre, France; e-mail: denis.ducreux{at}bct.ap-hop-paris.fr
BACKGROUND AND PURPOSE: Traumatic axonal injury is a primary brain abnormality in head trauma and is characterized by reduction of fractional anisotropy (FA) on diffusion tensor imaging (DTI). Our hypothesis was that patients with mild traumatic brain injury (TBI) have widespread brain white matter regions of reduced FA involving a variety of fiber bundles and show fiber disruption on fiber tracking in a minority of these regions.
MATERIALS AND METHODS: Ethics committee approval and informed consent were obtained. Twenty-one patients with mild TBI were investigated (men:women, 12:9; mean age ± SD, 32 ± 9 years). In a voxel-based comparison with 11 control subjects (men:women, 8:3; mean age, 37 ± 9 years) using z score analysis, patient regions with abnormally reduced FA were defined in brain white matter. MR imaging, DTI, and fiber tracking characteristics of these regions were described and analyzed using Pearson correlation, linear regression analysis, or the 
2 test when appropriate.
RESULTS: Patients had on average 9.1 regions with reduced FA, with a mean region volume of 525 mm3, predominantly found in cerebral lobar white matter, cingulum, and corpus callosum. These regions mainly involved supratentorial projection fiber bundles, callosal fibers, and fronto-temporo-occipital association fiber bundles. Internal capsules and infratentorial white matter were relatively infrequently affected. Of all of the involved fiber bundles, 19.3% showed discontinuity on fiber tracking.
CONCLUSION: Patients with mild TBI have multiple regions with reduced FA in various white matter locations and involving various fiber bundles. A minority of these fiber bundles show discontinuity on fiber tracking.