Bi-exponential diffusion signal decay in normal appearing white matter of multiple sclerosis.
OBJECTIVE
Our aim was to characterize bi-exponential diffusion signal changes in normal appearing white matter of multiple sclerosis (MS) patients.


METHODS
Diffusion parameters were measured using mono-exponential (0-1000 s/mm(2)) and bi-exponential (0-5000 s/mm(2)) approaches from 14 relapsing-remitting subtype of MS patients and 14 age- and sex-matched controls after acquiring diffusion-weighted images on a 3T MRI system. The results were analyzed using parametric or nonparametric tests and multiple linear regression models.


RESULTS
Mono-exponential apparent diffusion coefficient (ADC) slightly increased in controls (P=.09), but decreased significantly in MS as a function of age, nonetheless an elevated ADC was observed with increasing lesion number in patients. Bi-exponential analyses showed that the increased ADC is the result of decreased relative volume fraction of slow diffusing component (f(s)). However, the fast and slow diffusion components (ADC(f), ADC(s)) did not change as a function of either age in controls or lesion number and age in MS patients.


CONCLUSIONS
These data demonstrated that the myelin content of the white matter affects diffusion in relapsing-remitting subtype of multiple sclerosis that is possibly a consequence of the shift between different water fractions.
Department of Radiography, Faculty of Health Sciences, University of Pecs, H-7400 Kaposvar, Hungary.
Szilvia A
SA
Nagy
Mihaly
M
Aradi
Gergely
G
Orsi
Gabor
G
Perlaki
David Olayinka
DO
Kamson
Andrea
A
Mike
Hedvig
H
Komaromy
Attila
A
Schwarcz
Arpad
A
Kovacs
Jozsef
J
Janszky
Zoltan
Z
Pfund
Zsolt
Z
Illes
Peter
P
Bogner
D000328:Adult; D001921:Brain / Q000473:pathology*; D016022:Case-Control Studies; D054022:Cerebrum / Q000473:pathology; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D009103:Multiple Sclerosis / Q000175:diagnosis* / Q000473:pathology*; D009186:Myelin Sheath / Q000473:pathology; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D012044:Regression Analysis; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult