The Journal of Neuroscience, October 31, 2007, 27(44):11869-11876; doi:10.1523/JNEUROSCI.3647-07.2007
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Neurobiology of Disease
Diffusion Tensor Imaging Reliably Detects Experimental Traumatic Axonal Injury and Indicates Approximate Time of Injury
Christine L. Mac Donald,1
Krikor Dikranian,3
Philip Bayly,1,2
David Holtzman,3,4,5,6 and
David Brody4,6
Departments of 1Biomedical Engineering and 2Mechanical Engineering, Washington University, St. Louis, Missouri 63130, Departments of 3Anatomy and Neurobiology, 4Neurology, and 5Molecular Biology and Pharmacology, and 6Hope Center for Neurological Disorders, Washington University, St. Louis, Missouri 63110
Correspondence should be addressed to Dr. David Brody, Department of Neurology, Washington University, 660 South Euclid Avenue, Box 8111, St. Louis, MO 63110. Email: brodyd{at}neuro.wustl.edu
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.
Key words: magnetic resonance imaging; diffusion tensor imaging; traumatic brain injury; axonal injury; white matter injury; forensic imaging
Received May 16, 2007;
accepted Sept. 11, 2007.
Correspondence should be addressed to Dr. David Brody, Department of Neurology, Washington University, 660 South Euclid Avenue, Box 8111, St. Louis, MO 63110. Email: brodyd{at}neuro.wustl.edu
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