Zusammenfassung
The idea that the initiating event in the formation of all new multiple
sclerosis lesions is a focal blood-brain barrier (BBB) leakage associated
with perivascular inflammation has been challenged recently by the
observation of subtle abnormalities in some quantitative magnetic
resonance (MR) parameters (including the magnetization transfer
ratio) prior to lesion enhancement. MR diffusion imaging can non-invasively
quantify the average apparent diffusion coefficient (ADC(av)), a
measure of water molecule random motion that is sensitive to pathological
change in multiple sclerosis lesions and to abnormalities in the
normal-appearing white matter (NAWM). We therefore used MR diffusion
imaging to investigate the dynamic evolution of water diffusion
measurements in new enhancing multiple sclerosis lesions, in the
NAWM from which they arise, and in anatomically matched contralateral
NAWM regions from which no visible lesions develop. Gadolinium diethylenetriaminepentaacetic
acid (Gd)-enhanced MRI and MR diffusion studies were performed monthly
for 1 year in five multiple sclerosis patients with clinically and
radiologically active disease. The ADC(av) was calculated at each
time point of the study (before, during and after lesion appearance
on Gd-enhanced scans) for each new enhancing lesion, and for regions
matched for size and position in the contralateral NAWM. A steady
and moderate increase in ADC(av) in prelesion NAWM was observed,
which was followed by a rapid and marked increase at the time of
Gd enhancement and a slower decay after the cessation of enhancement.
In matched contralateral NAWM regions there was a significant but
milder increase in ADC(av) at the time of the first noted lesion
enhancement. These findings indicate that new focal lesions associated
with frank BBB leakage are preceded by subtle, progressive alterations
in tissue integrity beyond the resolution of conventional MRI. The
increases in ADC(av) in anatomically matched contralateral regions
after lesions have appeared supports the concept that structural
damage in lesions causes damage or dysfunction in connected areas
of NAWM.
- 10908196
- adult,
- ale,
- brain,
- computer-assisted,
- contrast
- disease
- dtpa,
- fem,
- gadolinium
- gov't,
- humans,
- image
- imaging,
- magnetic
- male,
- media,
- multiple
- non-u.s.
- processing,
- progression,
- reference
- research
- resonance
- sclerosis,
- support,
- values,
Nutzer