Diffusion Tensor Imaging

Abstract

Diffusion tensor imaging (DTI) is an advance in MRI scanning that adds clinically significant detail about structure and function that cannot be detected with other MRI scanning techniques. It is based on calculating the main directions of axonal trajectories in each voxel of the scan. These can be traced by tractography to create accurate images of the white matter connections of the brain. Visualization of structures such as the pyramidal tract, arcuate fasciculus, and optic radiation has improved the safety of brain tumor resection by allowing these critical eloquent structures to be located and avoided during planning of resections. Fractional anisotropy (FA) is a term that describes the degree to which the neural tissue in a given voxel demonstrates coherent directional diffusion. Because this property appears to decrease in the setting of various pathologies, or as a consequence of trauma, DTI FA measurements have been used to identify the location and extent of injuries to functional tracts in the brain. DTI is also applied to spinal cord imaging to assess the severity of trauma or to gauge the significance of spinal cord compression in cervical spondylotic myelopathy. The method is also useful in the assessment of peripheral nerve pathology.