title: Whole brain myelin mapping using T1- and T2-weighted MR imaging data.
abstract: Despite recent advancements in MR imaging, non-invasive mapping of myelin in the brain still remains an open issue. Here we attempted to provide a potential solution. Specifically, we developed a processing workflow based on T1-w and T2-w MR data to generate an optimized myelin enhanced contrast image. The workflow allows whole brain mapping using the T1-w/T2-w technique, which was originally introduced as a non-invasive method for assessing cortical myelin content. The hallmark of our approach is a retrospective calibration algorithm, applied to bias-corrected T1-w and T2-w images, that relies on image intensities outside the brain. This permits standardizing the intensity histogram of the ratio image, thereby allowing for across-subject statistical analyses. Quantitative comparisons of image histograms within and across different datasets confirmed the effectiveness of our normalization procedure. Not only did the calibrated T1-w/T2-w images exhibit a comparable intensity range, but also the shape of the intensity histograms was largely corresponding. We also assessed the reliability and specificity of the ratio image compared to other MR-based techniques, such as magnetization transfer ratio (MTR), fractional anisotropy (FA), and fluid-attenuated inversion recovery (FLAIR). With respect to these other techniques, T1-w/T2-w had consistently high values, as well as low inter-subject variability, in brain structures where myelin is most abundant. Overall, our results suggested that the T1-w/T2-w technique may be a valid tool supporting the non-invasive mapping of myelin in the brain. Therefore, it might find important applications in the study of brain development, aging and disease.
authors.affiliation: Neural Control of Movement Laboratory, Department of Heath Sciences and Technology, ETH Zurich Zurich, Switzerland ; Department of Experimental Psychology, University of Oxford Oxford, UK.
authors.forename: Marco
authors.initials: M
authors.lastname: Ganzetti
authors.affiliation: Neural Control of Movement Laboratory, Department of Heath Sciences and Technology, ETH Zurich Zurich, Switzerland ; Laboratory of Movement Control and Neuroplasticity, Department of Kinesiology, KU Leuven Leuven, Belgium.
authors.forename: Nicole
authors.initials: N
authors.lastname: Wenderoth
authors.affiliation: Neural Control of Movement Laboratory, Department of Heath Sciences and Technology, ETH Zurich Zurich, Switzerland ; Department of Experimental Psychology, University of Oxford Oxford, UK.
authors.forename: Dante
authors.initials: D
authors.lastname: Mantini
keywords: brain integrity assessment; brain mapping; magnetic resonance imaging; myelin enhanced contrast; myelin mapping