By Maria Bishop
Special to DG News
BOSTON, MA -- April 27, 2001 -- Magnetic resonance (MR) imaging can be a powerful tool to evaluate lesion changes in longitudinal studies of multiple sclerosis (MS).
Brazilian researchers at the 39th Meeting of the American Society of Neuroradiology (ASNR) in Boston, Massachusetts, noted that active demyelination (loss of nerve-fiber insulation) is shown to be accompanied by an increase of choline (Cho)/creatine (Cr) ratio.
Dr. Marie C. G. Otaduy of The School of Medicine of the University of Sao Paulo in Sao Paulo, Brazil, noted that on average, MS lesions presented higher values of myoinositol (mI)/Cr, Cho/Cr, lipids (lip)/Cr and a lower ratio of N-acetyl aspartate (NAA)/Cr than control white matter upon MR imaging. Seven out of 29 lesions showed an abnormally high lipid signal, considered to be a marker of active demyelination. Compared to the other 22 lesions studied, these seven lesions presented a higher Cho/Cr ratio and a lower mI/Cr ratio.
Dr. Otaduy's research team examined 24 MS patients with Expanded Disability Status Scale ratings ranging from 1.5 to 8, as well as 10 healthy volunteers. All were examined using a 1.5 T unit. Using the single voxel PRESS technique, 1H spectra were obtained with two different echo times (30 and 135 milliseconds) and a repetition time of two seconds.
Metabolite intensities of NAA, Cho, mI and lip were measured relative to Cr. An mI/Cr increase, it was noted, might become more pronounced only at a later stage.
The diagnosis of clinically definite MS requires two neurological events (separated in time and in location) suggesting demyelination in the central nervous system. Studies have shown that individuals who experience a single occurrence of a sign or symptoms of demyelination and multiple clinically "silent" MRI-detected brain lesions are at high risk for developing clinically definite MS within several years.