Diffusion Tensor Magnetic Resonance Imaging of Spinal Cord Injury

Traumatic injury to spinal cord affects thousands of persons and costs billions of dollars annually in treatment expenses. Although less than a decade ago spinal cord injury was thought of as an untreatable condition, many promising new treatments are now in the experimental stage. Rodent models are essential for validating new therapeutic trials. This paper presents results of in vivo magnetic resonance imaging of rodent spinal cord based on new modality of diffusion tensor MRI (DT-MRI) implemented on a 7T scanner. An RF coil, implanted in the animal, is used for improving signal level of acquired images. Image distortion induced by eddy currents is reduced using image processing techniques. Accuracy of estimated diffusion tensor values is enhanced using a biexponential diffusion modeling and nonlinear regression analysis. Diffusion tensor is used to obtain rotationally invariant anisotropy maps, which are useful for evaluating the pathology and integrity of fiber tracts. Results show that diffusion tensor anisotropy maps are significantly affected by injury, suggesting that DT-MRI provides unique information about fiber tracts in injured spinal cord. Serial study is presented for monitoring the status of spinal cord injury.