Magnetic resonance monitoring of spinal cord injury using implanted RF coil

In vivo magnetic resonance imaging of rodent spinal cord is presented here based on the new modality of diffusion tensor MRI (DT-MRI) implemented on a 7 Tesla scanner. An RF coil implanted in rats is used to improve the signal to noise ratio. Adjustment of various parameters for optimizing the coil performance is described. Complete diffusion tensor has been determined by acquiring images with diffusion gradients applied along seven independent directions, each incremented in sixteen gradient steps. The attenuation of diffusion-weighted images is characterized by biexponential decay, and the images are analyzed using a nonlinear regression for calculating rotationally invariant diffusion anisotropy maps. These maps are useful for evaluating the pathology and integrity of fiber tracts. Diffusion tensor anisotropy maps are shown to be significantly affected by injury, suggesting that DT-MRI using implanted RF coil provides unique information about fiber tracts in the injured spinal cord.