By Maria Bishop
Special to DG News
BOSTON, MA -- April 30, 2001 -- The long-term outcome of multiple-sclerosis (MS) patients can now be quantified using magnetization-transfer imaging of normal-appearing white matter (NAWM) of the brain, said a team of international researchers at the 39th Meeting of the American Society of Neuroradiology (ASNR) in Boston, Massachusetts.
Magnetization transfer imaging can detect focal abnormalities in NAWM before the appearance of lesions on conventional magnetic resonance (MR) imaging. At baseline, the MS patients in this study demonstrated a significant difference in NAWM magnetization transfer ratios (MTr) and brain MTr between patients with stable and progressive evolution of this disease, as well as 12 normal control subjects.
The student's t- test was used to assess the differences between all groups, and Spearman rank-order correlation was performed between MTr and Expanded Disability Status Scale (EDSS) changes over the subsequent five years to create Spearman's rank correlation coefficients (SRCC).
The changes in MS patients' EDSS values correlated strongly with NAWM MTr (SRCC = 0.76) and brain MTr (SRCC = 0.70). NAWM MTr in the MS patients was significantly lower than in the normal controls.
Dr. Antonio C. Santos of the Montreal Neurological Institute in Montreal, Canada led the team in that assessed the clinical and magnetic resonance (MR) imaging data. He noted that the MS patients were divided into stable and progressive groups based on changes in their EDSS scores. The researchers used the MTrs from lesions, NAWM and the whole brain to determine long-term outcomes. (Lesions were identified on T2-weighted MR imaging.)
The unique clinical characteristics of primary/progressive MS, in particular, pose diagnostic difficulties-both in excluding other causes of progressive syndromes and in confirming the diagnosis of MS.
While MR is the preferred method of imaging the brain to detect the presence of plaques or scarring caused by MS, the diagnosis of MS cannot be made solely on the basis of MR imaging, nor can long-term evaluation.