Magnetization transfer ratio histogram analysis of gray matter in relapsing-remitting multiple sclerosis

BACKGROUND AND PURPOSE: Gray matter may be affected by multiple sclerosis ( MS), a white matter disease. Magnetization transfer ratio (MTR) is a sensit ive and quantitative marker for structural abnormalities, and has been used frequently in the imaging of MS, In this study, we evaluated the amount of MTR of gray matter among patients with relapsing-remitting MS and healthy control subjects as well as the correlation between gray matter MTR abnorma lity and neurologic disability associated with relapsing-remitting MS. METHODS: We obtained fast spin-echo dual-echo and magnetization transfer (w ith and without MT saturation pulses) images from eighteen patients with re lapsing-remitting MS and 18 age-matched healthy control subjects. Gray matt er was segmented using a semiautomated system. Gray matter MTR histogram pa rameters, Kurtzke Expanded Disability Status Scale (EDSS), total T2 lesion volume, and gray matter volumes were obtained for statistical analysis. RESULTS: A significant difference was found in gray matter MTR between pati ents with relapsing-remitting MS and healthy subjects (mean and median). Gr ay matter MTR histogram normalized peak heights in patients inversely corre lated with EDSS (r = -0.65, P = .01). There was also an inverse correlation between mean MTR of gray matter and total T2 lesion volume. CONCLUSION: The MTR of gray matter significantly differed between patients with relapsing-remitting MS and healthy control subjects, suggesting that M S is a more diffuse disease affecting the whole brain, and neuronal damage accumulates in step with T2 lesion volume. Our finding of the relationship between gray matter MTR and EDSS indicates that measurement of gray matter abnormality may be a potentially useful tool for assessing clinical disabil ity in MS.