الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 261 |  |  |
| | | from | 261 | | |
Abstract
Multiple sclerosis is neurodegenerative disease, targeting the central nervous system which is autoimmune in nature. it is mediated by autoreactive lymphocytes that cross the blood-brain barrier and enter the CNS where they cause local inflammation that results in demyelination, gliotic scarring, and axonal loss. The phenotypes of MS range widely from a single demyelinating event termed Clinically Isolated Syndrome to a Secondary Progressive phenotype, relapsing-remitting MS is the most common phenotype (85%) of all multiple sclerosis patients. The diagnosis of MS is based on a combination of clinical findings, imaging, and laboratory data using the current diagnostic criteria known as the Revised McDonald Criteria, the diagnosis of MS requires dissemination in space and time. MRI is a method of choice to support the clinical diagnosis of MS. MRI is one of the components proposed in McDonald criteria for diagnosing MS. However, the application of MRI varies among different forms of the disease. Although the role of clinical management & scientific investigation of MS increasing, but still conventional magnetic resonance imaging (MRI) is of limited association with clinical progression of cases, also it has low sensitivity & specificity in normal-appearing white matter affection, but diffusion tensor imaging (DTI) technique found to be more sensitive in identifying the tissue damage (normally appearing white matter in conventional techniques of MRI). Mean diffusivity & Fractional anisotropy (FA) (one of DTI quantitative indices) evaluate widespread tissue damage outside the lesions seen by conventional MRI, it measures the directionality of diffusion inside tissues. Micro structural changes in NAWM (normal appearing white matter) in early stages of MS detected by diffusion tensor image technique are seen in all types of MS.