Role of MRI diffusion tensor imaging in assessment of normal appearing white matter in cases of multiple sclerosis

ABSTRACT

Background: Multiple sclerosis [MS] is an inflammatory demyelinating condition of the central nervous system [CNS] that is generally considered to be autoimmune in nature. White matter tracts are affected, including those of the cerebral hemispheres, infratentorium, and spinal cord. Several methods have been proposed, mainly using conventional MR modalities like T1, FLAIR or T2 images and enhanced MRI to delineate lesions. Conventional MR techniques cannot give detailed information about the integrity and location of WM tracts. Diffusion MRI is one of the non-conventional MRI techniques used for assessment of multiple sclerosis. The emergence of diffusion tensor imaging [DTI] is of great interest in MS. DTI probe the details of water diffusion within tissues, and could therefore reveal alterations in normal appearing white matter fibers before being visible in conventional MRI. Fractional anisotropy [FA], is the measure of the portion of the diffusion tensor that results from anisotropy [i.e, a measure of the directionality of the molecular motion of water]