Correlates of MS disability assessed in vivo using aggregates of MR quantities

Objectives: To assess the magnitude of the correlations between disability and composite MRI scores in patients with MS. Methods: T2- and T1-weighted MRI, magnetization transfer imaging, diffusion tenser imaging, and MRS imag ing scans of the brain from 23 patients with MS were obtained. T2 lesion vo lume, T1 lesion volume, brain magnetization transfer ratio, average brain d iffusivity ((D) over bar), and brain,N-acetylaspartate/creatine ratio were measured. Results: The correlations between the Expanded Disability Status Scale (EDSS) score and each of the MR quantities taken in isolation were no t significant, with the exception of the correlation between EDSS and the N AA/creatine ratio (r = -0.50; p = 0.01). In contrast, three of the composit e MR scores computed using regression models were strongly correlated with the EDSS scores (r range, 0.58 to 0.73; p range, 0.004 to 0.0001). The mode l that included T2 and T1 lesion volumes and brain (D) over bar explained 3 4% of the EDSS variance; the model that included T2 and T1 lesion volumes a nd brain N-acetylaspartate/creatine ratio explained 36% of the EDSS varianc e; the model that included T1 lesion volume, brain (D) over bar, and brain N-acetylaspartate/creatine ratio explained 53% of the EDSS variance. Conclu sions: The results suggest that multiparametric MR models have the potentia l to provide powerful measures to monitor MS evolution.