EARLY STRUCTURAL-CHANGES IN ACUTE MS LESIONS ASSESSED BY SERIAL MAGNETIZATION-TRANSFER STUDIES

Background: Whether acute MS lesions are primarily inflammatory or dem yelinative is unresolved. Our study examined acute MS lesions longitud inally by quantitative magnetization transfer (MT), an MRI technique t hat identifies tissue integrity and destruction. Methods: Four MS pati ents were studied by serial MRI including MT, conventional T2-weighted images, and postgadolinium T1-weighted images for 9 to 12 months. In 15 new lesions, the MT ratio (MTR) was calculated retrospectively. Res ults: In 13 lesions, a marked decrease in the MTR was present early du ring the first 2 months after the onset of the lesion and was followed by a variable increase. In two other lesions, the MTR progressively d eclined. Conclusions: These results suggest that major early structura l changes compatible with demyelination and followed by remyelination and gliosis, or by continuous demyelination, occur in new MS lesions. The various MTR profiles provide in vivo confirmation of the current k nowledge of the progression in MS lesions. Furthermore, MTR may be use d to monitor in vivo drug efficacy in new MS lesions.