Towards an in-vivo and post-mortem characterization of chronic multiple sclerosis lesions using susceptibility related mechanisms of contrast at ultra-high field MRI with R2* and phase images

Introduction: R2 and phase images derived from high-resolution 7 Tesla magnetic susceptibility-weighted MRI provide a rich contrast in healthy and diseased human brain. Yet, the sources that contribute to this contrast are not fully understood. Previous studies suggest that iron and myelin brain content may each contribute to R2 and phase in a different manner [1]. In this study, we used multiple sclerosis (MS) as a model of disease to investigate contribution of the iron and myelin content to pathological contrast. The pathological hallmark of MS is the classical demyelinated plaque. Iron was also shown to accumulate in chronic lesions as well as in peri-lesional areas [2, 3]. The imbalance of the iron/myelin ratio that can be present at variable extent in MS lesions and therefore could provide valuable clues to the role of iron and myelin in GRE contrast.