Pathologic damage in MS assessed by diffusion-weighted and magnetization transfer MRI.
OBJECTIVE
To compare diffusion characteristics of MS lesions, normal-appearing white matter (NAWM) from patients, and normal white matter from control subjects, and to investigate the correlations between the magnetization transfer ratio (MTR) and a directionally averaged tissue water diffusion coefficient (D) in patients.


BACKGROUND
MS and other pathologic processes that modify tissue integrity can result in abnormal diffusion of water molecules detectable by diffusion-weighted imaging (DWI).


METHODS
Conventional dual-echo and DWI scans were obtained from 35 patients with relapsing-remitting MS and 24 healthy control subjects. MT scans were also obtained from the patients. After coregistration of all scans, MTR and D values from MS lesions and NAWM in different regions were marked using the dual-echo scans as a reference. D values from the same brain regions in control subjects were acquired. Histograms of MTR and D were also produced.


RESULTS
Patients with MS had significantly higher D values in all the areas studied. Moreover, histogram metrics (peak height, peak site, and average D) from patients were substantially different from those of control subjects. In patients, average lesion D and MTR were markedly different from those in the NAWM. There was an inverse correlation between average lesion MTR and D inside lesions, whereas no correlation was found for average MTR and D taken from the histograms.


CONCLUSIONS
DWI detects severe tissue disruption inside lesions and subtle widespread abnormalities in NAWM in patients with relapsing-remitting MS. MT and DWI may provide information about different aspects of brain pathology in MS.
Cercignani
M
M
Department of Neuroscience, Scientific Institute Ospedale San Raffaele, University of Milan, Italy.
Iannucci
G
G
Rocca
M A
MA
Comi
G
G
Horsfield
M A
MA
Filippi
M
M
D000328:Adult; D001921:Brain / Q000473:pathology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009103:Multiple Sclerosis / Q000473:pathology*