Magnetization transfer imaging of patients with definite MS and negative conventional MRI

Objective: To assess, in a group of patients with clinically or laboratory- supported definite MS and negative conventional MRI scans of the brain, whe ther magnetization transfer imaging (MTI) is able to detect subtle white ma tter changes. Background: MTI of the brain in patients with MS frequently d emonstrates the presence of microscopic damage to white matter, which appea rs normal on conventional MRI. Methods: Brain MRI and MTI scans were obtain ed from 11 patients with negative conventional MRIs of the brain, selected from 618 clinically or laboratory-supported definite MS cases scanned in th e last 2 years in three Italian MS centers. Results: Compared with control subjects, patients had significantly lower mean MT ratios (MTR) in the pens , cerebellum, and periventricular regions. The percentages of pixels with M TR values below 1, 2, and 3 SD of the mean MTR value of the control subject s were 7.6% (range, 3.2% to 11.8%), 5.2% (range, 2.0% to 8.5%), and 3.6% (r ange, 1.2% to 6.1%), respectively. They were mainly located in the white ma tter of the centra semiovalia, and usually were isolated. Conclusions: MTI can detect white matter abnormalities in patients with MS and negative conv entional brain MRI scans. The detection of such abnormalities may increase diagnostic confidence in those cases where MS is clinically suspected, but conventional MRI does not suggest the diagnosis.