Multimodel Magnetic Resonance Imaging (MRI)of Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorders

To investigate multimodel MRI exploring the pathophysiology of multiple sclerosis and neuromyelitis optica spectrum disorders. The investigators use multimodel MRI to evaluate the extent of blood-brain barrier and white matter fiber tracts destruction , iron deposition and cerebral blood flow of associated regions in multiple sclerosis and neuromyelitis optica spectrum disorders using contrast-enhanced magnetic resonance imaging , quantitative susceptibility mapping, diffusion tension imaging, and arterial spin labeling with post labeling delay of 2.0 seconds. Transfer constant volume , magnetic susceptibility, cerebral blood flow and fractional anisotropy(FA) value were measured in lesion and normal appearing white matter.