Diffusion tensor imaging predicts hyperacute spinal cord injury severity

Experimental strategies that focus on ventral white matter (VWM) preservation during the hyperacute phase hold great potential for our improved understanding of functional recovery following traumatic spinal cord injury (SCI). Critical comparisons of human SCI to rapidly accumulating data derived from rodent models are limited by a basic lack of in vivo measures of subclinical pathophysiologic changes and white matter damage in the spinal cord. Spinal cord edema and intraparenchymal hemorrhage demonstrated with routine MR sequences have limited value for predicting functional outcomes in SCI animal models and in human patients. We recently demonstrated that in vivo derived diffusion tensor imaging (DTI) parameters are sensitive and specific biomarkers for spinal cord white matter damage. In this study, non-invasive in vivo DTI was utilized to evaluate the white matter of C57BL/6 mice 3 h after mild (0.3 mm), moderate (0.6 mm), or severe (0.9 mm) contusive SCI. In the hyperacute phase, relative anisotropy maps provided excellent gray-white matter contrast in all degrees of injury. In vivo DTI-derived measurements of axial diffusion differentiated between mild, moderate, and severe contusive SCI with good histological correlation. Cross-sectional regional measurements of white matter injury severity between dorsal columns and VWM varied with increasing cord displacement in a pattern consistent with spinal cord viscoelastic properties.