*These authors contributed equally to this work.

Previous authors have shown that the transverse relaxivity R2 * and frequency shifts that characterize gradient echo signal decay in magnetic resonance imaging are closely associated with the distribution of iron and myelin in the brain’s white matter. In multiple sclerosis, iron accumulation in brain tissue may reflect a multiplicity of pathological processes. Hence, iron may have the unique potential to serve as an in vivo magnetic resonance imaging tracer of disease pathology. To investigate the ability of iron in tracking multiple sclerosis-induced pathology by magnetic resonance imaging, we performed qualitative histopatho-logical analysis of white matter lesions and normal-appearing white matter regions with variable appearance on gradient echo magnetic resonance imaging at 7 Tesla. The samples used for this study derive from two patients with multiple sclerosis and one non-multiple sclerosis donor. Magnetic resonance images were acquired using a whole body 7 Tesla magnetic resonance imaging scanner equipped with a 24-channel receive-only array designed for tissue imaging. A 3D multi-gradient echo sequence was obtained and quantitative R2 * and phase maps were reconstructed. Immunohistochemical stainings for myelin and oligo-dendrocytes, microglia and macrophages, ferritin and ferritin light polypeptide were performed on 3- to 5-mm thick paraffin sections. Iron was detected with Perl’s staining and 3,30-diaminobenzidine-tetrahydrochloride enhanced Turnbull blue staining