Diffusion tensor imaging has been used extensively as a research tool to understand the structural changes associated with white matter pathology. Using water diffusion as the basis to construct anatomic details, diffusion tensor imaging offers the potential to identify structural and functional adaptations before gross anatomical changes, such as lesions and tumors, become apparent on conventional MRI. Over the past 10 years, further parameters, such as axial and radial diffusivity, have been developed to characterize white matter changes specific to axons and myelin. In this paper, the potential application and outstanding issues on the use of diffusion tensor imaging directional diffusivity as a biomarker in axonal and myelin damage in neurological disorders will be reviewed.
Keywords: Alzheimer’s disease; MRI; acute and chronic CNS disorders; acute disseminated encephalomyelitis; axial diffusivity; axonal injury; diffusion tensor imaging; leukodystrophy; multiple sclerosis; myelin damage; radial diffusivity.