DETECTION OF ACUTE PATHOLOGICAL-CHANGES FOLLOWING EXPERIMENTAL TRAUMATIC BRAIN INJURY USING DIFFUSION-WEIGHTED MAGNETIC-RESONANCE-IMAGING

Standard magnetic resonance imaging (MRI) has been shown to be remarka bly insensitive to acute changes following traumatic brain injury. Bec ause diffusion-weighted MRI has recently demonstrated excellent sensit ivity to acute ischemic injury and other CNS abnormalities, we evaluat ed the use of diffusion MRI for the detection of pathologic changes in the rat brain during the first hours following parasagittal fluid per cussion brain injury. Diffusion MRI was able to demonstrate a signific ant diffusion decrease in the primary cortical contusion injury and a comparable decrease in the ipsilateral thalamus. Tissue damage in the thalamus region is much weaker than in the cortex, but the thalamus is a primary site of axonal and dendritic injury in this model. T2 imagi ng in the same subjects showed slight enhancement in the neighborhood of the injured cortex but was unable to demonstrate injury elsewhere. Diffusion imaging was superior to T2 at demonstrating injury and the p rominent diffusion decrease in the thalamus suggests that diffusion MR I is preferentially sensitive to axonal or dendritic injury.