Abnormal diffusivity of normal appearing brain tissue in multiple sclerosis: a diffusion-weighted MR imaging study.

Objective: To assess whether water diffusivity in normal appearing brain tissue including white and gray matter of multiple sclerosis (MS) patients shown by diffusion-weighted imaging (DWI) differs from normal individuals.

Material And Method: Conventional MRI and DWI were performed in 37 multiple sclerosis patients and 31 control subjects, matched for age and sex. Quantitative diffusivity values were obtained from variable locations of normal appearing white and gray matter from both hemispheres by using a standardized region of interest template. +/- 2. 9 x 10(-5) mm2/s and 85.90 x 10(-5) +/- 2.45 x 10(-5) mm2/s) than normal control subjects (NAWM: 73.46 x 10(-5) +/- 1.77 x 10(-5) mm2/s and NAGM: 82.90 x 10(-5) +/- 0.91 x 10(-5) mm2/s) with p-value < 0.0001.

Conclusion: Water diffusivity was higher in all NAWM regions, deep gray matter regions, and some cortical gray matter region of MS patients than normal controls. DWI can quantify the presence and extent of MRI-undetectable pathology in the normal appearing brain tissue that were the disease burden.