title: Diffusion tensor imaging reliably detects experimental traumatic axonal injury and indicates approximate time of injury.
abstract: Traumatic axonal injury (TAI) may contribute greatly to neurological impairments after traumatic brain injury, but it is difficult to assess with conventional imaging. We quantitatively compared diffusion tensor imaging (DTI) signal abnormalities with histological and electron microscopic characteristics of pericontusional TAI in a mouse model. Two DTI parameters, relative anisotropy and axial diffusivity, were significantly reduced 6 h to 4 d after trauma, corresponding to relatively isolated axonal injury. One to 4 weeks after trauma, relative anisotropy remained decreased, whereas axial diffusivity "pseudo-normalized" and radial diffusivity increased. These changes corresponded to demyelination, edema, and persistent axonal injury. At every time point, DTI was more sensitive to injury than conventional magnetic resonance imaging, and relative anisotropy distinguished injured from control mice with no overlap between groups. Remarkably, DTI changes strongly predicted the approximate time since trauma. These results provide an important validation of DTI for pericontusional TAI and suggest novel clinical and forensic applications.
authors.affiliation: Department of Biomedical Engineering, Washington University, St. Louis, Missouri 63130, USA.
authors.forename: Christine L
authors.initials: CL
authors.lastname: Mac Donald
authors.forename: Krikor
authors.initials: K
authors.lastname: Dikranian
authors.forename: Philip
authors.initials: P
authors.lastname: Bayly
authors.forename: David
authors.initials: D
authors.lastname: Holtzman
authors.forename: David
authors.initials: D
authors.lastname: Brody
mesh_terms: D016564:Amyloid beta-Protein Precursor / Q000378:metabolism; D000818:Animals; D001369:Axons / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D001921:Brain / Q000378:metabolism / Q000473:pathology*; D020833:Diffuse Axonal Injury / Q000175:diagnosis* / Q000378:metabolism; D038524:Diffusion Magnetic Resonance Imaging; D004195:Disease Models, Animal; D018450:Disease Progression; D005260:Female; D008297:Male; D051379:Mice; D046529:Microscopy, Electron, Transmission / Q000379:methods; D009419:Nerve Tissue Proteins / Q000378:metabolism; D015203:Reproducibility of Results; D013997:Time Factors
chemical_list: D016564:Amyloid beta-Protein Precursor; D009419:Nerve Tissue Proteins