In Vivo Diffusion Tensor Derived Fiber Orientation Failed to Detect Secondary Axonal Injury

Joong Hee Kim¹, Sheng-Kwei Song¹

The sensitivity of DTI derived anisotropy, diffusivity, and tractography to primary and secondary white matter injury was examined. Rat spinal cords undergoing right lateral transection or sham operation were examined using DTI at acute and 7 days after injury. At acute, the axial diffusivity localized the epicenter with severe diffusivity reduction where diffusion anisotropy failed to detect the injury. At 7 days after injury, both axial diffusivity and anisotropy visualized the diffuse axonal injury from epicenter in close agreement with histological validation. However, the main orientation of axonal fiber was largely preserved failing to detect the axonal injury.