Apparent diffusion coefficients in benign and secondary progressive multiple sclerosis by nuclear magnetic resonance.

The diffusion characteristics of water in brain white matter were studied in patients with benign and secondary progressive multiple sclerosis (MS), and also in normal controls. In the MS patients, both lesions and normal-appearing white matter (NAWM) were examined to assess whether pathological differences might be evident from the diffusion behavior. A volume-selective technique was used to reduce data acquisition time and improve the reliability and precision of the measurements. This also allowed the time-dependence of apparent diffusion coefficients to be assessed. While lesions from both patient groups showed an elevated diffusion coefficient, no differences between the two groups were found. In addition, NAWM was elevated for both patient groups compared with the control group, although this was only statistically significant for patients with a benign disease course. The degree of elevation of the diffusion coefficient within the individual lesions measured was not related to the disability of the patient. Pathological differences between lesions in patients with different disease courses, if they exist, have not been detected in this study of brain water diffusion.