Description (from grant): Recent histopathologic studies in MS have shown that inflammation of the meninges may be responsible for damage to gray matter in brain and spinal cord, neurodegeneration, and a more disabling form of MS. We will validate gadolinium-enhanced 7T MPFLAIR MRI as an in vivo biomarker of meningeal inflammation and explore this hypothesis in living patients. If successful, this study will spur development of treatments geared towards meningeal inflammation and provide a tool to screen those who may benefit and monitor treatment response. The choice of leptomeningeal enhancement as an in vivo biomarker of meningeal inflammation will be justified through comparisons to other MRI sequences and other field strengths in addition to demonstration of a link between leptomeningeal enhancement and spinal fluid markers of meningeal inflammation through cytokine profiling and flow cytometry. We will also use this imaging tool to demonstrate an association between meningeal inflammation and cortical pathology (cortical lesions and cortical relaxometry alterations on 7T MRI) and neurodegeneration (retinal nerve fiber layer thinning on OCT).