Effect of Tysabri in Patients With Relapsing-Remitting Multiple Sclerosis: A Follow-up Magnetization Transfer Imaging (MTI) Study

Magnetization transfer imaging (MTI) is a widely used tool for characterizing the evolution of multiple sclerosis (MS) lesions and normal appearing brain tissue (NABT). As remyelination and demyelination are heterogeneous in each lesion and NABT, techniques such as voxel-wise based MTR dynamic mapping may help predict an individual's clinical course, as well as the effect of treatment, by revealing evidence of myelin repair and neuroprotection. Natalizumab (Tysabri) showed a robust effect on the decrease of inflammation in phase II and III clinical trials, as evidenced by the decrease in Gd enhancing and T2 lesions and on the decrease of clinical activity as measured by reduction of clinical relapses and progression of disability. The effect of Tysabri on non-conventional measures is only partially known.