Evaluation of multiple sclerosis by ¹H spectroscopic imaging at 4.1 T

The authors report on high-field (4.1 T) magnetic resonance ¹H spectroscopic imaging studies on eight patients with relapsing remitting multiple sclerosis (mean expanded disability status scale (EDSS) 1.0) and eight normal controls. Using T₁-weighted imaging to determine lesion position, the authors found the ratios of choline/N-acetyl (NA) compounds and creatine/NA were increased significantly in the multiple sclerosis (MS) patients relative to controls in lesioned tissue, adjacent to lesion, far removed from lesions as well as in periventricular tissue. The gray matter creatine/NA was mildly increased (P < 0.01) in the MS patients, whereas the elevated gray-matter ratio of choline/NA was of borderline significance (P = 0.13). A more detailed comparison of white-matter and mean gray-matter metabolite values indicates that creatine is increased greatest in areas far from lesions. This is in contrast to choline, which was greatest in lesions, and NA, which was smallest in lesions. It is postulated that the creatine increase may reflect an astrocytic (gliotic) or oligodendrocytic remyelinating process. The increased choline most likely reflects varying levels of inflammation and membrane turnover, whereas the NA decrease is representative of axonal dysfunction or loss.