Imaging intralesional heterogeneity of sodium concentration in multiple sclerosis: Initial evidence from 23 Na-MRI.

Sodium MRI (23 Na-MRI) has been used to non-invasively quantify tissue sodium but has been limited by low spatial resolution. Here we demonstrate for the first time that high resolution 23 Na-MRI reveals the spatial heterogeneity of sodium concentration within a multiple sclerosis (MS) lesion. A patient with treatment-naïve relapsing-remitting MS and a ring-enhancing lesion was imaged using 23 Na-MRI. The periphery of the lesion demonstrated an elevated total sodium content compared to the normal appearing white and grey matter (p<0.01), as well as a heterogeneous distribution of both the total tissue sodium concentration and the intracellular-weighted sodium concentration.