"One of the most important reasons for the study was to understand which regions of the brain are most predictive of a second clinical attack," he said. "No one has really looked at this over the long term in a clinical trial."
The researchers used contrast-enhanced MRI for initial assessment of 216 CIS patients. They performed follow-up scans at six months, one year and two years. Over two years, 92 of 216 patients, or 42.6 percent, converted to clinically definite MS. Decreases in thalamic volume and increase in lateral ventricle volumes were the only MRI measures independently associated with the development of clinically definite MS.
"First, these results show that atrophy of the thalamus is associated with MS," Dr. Zivadinov said. "Second, they show that thalamic atrophy is a better predictor of clinically definite MS than accumulation of T2-weighted and contrast-enhanced lesions."
The findings suggest that measurement of thalamic atrophy and increase in ventricular size may help identify patients at high risk for conversion to clinically definite MS in future clinical trials involving CIS patients.
"Thalamic atrophy is an ideal MRI biomarker because it's detectable at very early stage," Dr. Zivadinov said. "It has very good predictive value, and you will see it used more and more in the future."
The research team continues to follow the study group, with plans to publish results from the four-year follow-up next summer. They are also trying to learn more about the physiology of the thalamic involvement in MS.
"The next step is to look at where the lesions develop over two years with respect to the location of the atrophy," Dr. Zivadinov said. "Thalamic atrophy cannot be explained entirely by accumulation of lesions; there must be an independent component that leads to loss of thalamus."
MS affects more than 2 million people worldwide, according
|Contact: Linda Brooks|
Radiological Society of North America