Surface-based techniques reveal regions of reduced cortical magnetization transfer ratio in patients with MS

Introduction: Evidence from pathological studies continues to underscore the significant involvement of cortical grey matter (GM) in multiple sclerosis (MS) [Stadelmann, C., et al., Curr Opin Neurol, 2008. 21(3):229-34]. Although some of this cortical pathology is now detectable as a result of advances in sequence development (e.g., double inversion recovery), contiguous areas of subpial demyelination, which are the most common subtype of cortical lesions sampled at autopsy, remain largely undetectable with conventional methods [Geurts JJ, et al., AJNR., 2005 26(3):572-7]. Magnetization transfer imaging has already been shown to be sensitive to changes in myelin content in white matter [Pike, G B, et al., Radiology, 2000. 215(3):824-30; Schmierer, K., et al., Ann Neurol, 2004. 56(3): 407-15]. We used a novel surface-based method to quantify the extent of subpial decreases in magnetization transfer ratio (MTR) in order to identify regions of cortical demyelination. Our method was applied to group data from MS patients and normal controls, as well as to data from individuals to identify areas that differed from the control group.