Abnormal Diffusivity of Normal Appearing Brain Tissue in Multiple Sclerosis: A Diffusion-Weighted MR Imaging Study
Warinthorn Phuttharak MD*, Waneerat Galassi MD**, Vallop Laopaiboon MD*, Malinee Laopaiboon PhD***, John R Hesselink MD, FACR****
Affiliation : * Department of Radiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand ** Department of Radiology, Faculty of Medicine, Naresuan University, Phitsanulok, Thailand *** Department of Biostatistics, Faculty of Public Health, Khon Kaen University, Khon Kaen, Thailand **** Department of Radiology, UCSD Medical Center, San Diego, California, USA
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.
Materials and Methods : 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 loca-
tions of normal appearing white and gray matter from both hemispheres by using a standardized region of
interest template.
Results : Mean diffusivity was higher in both normal appearing white matter (NAWM) and normal appearing
gray matter (NAGM) of MS patients (mean + SD: 85.71 x 10-5 + 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.
Keywords : Diffusivity, Multiple sclerosis (MS), Diffusion-weighted imaging (DWI), Normal appearing white matter (NAWM), Normal appearing gray matter (NAGM)
