Investigation of microscopic diffusion anisotropy reveals microstructural changes in normal aging of the human brain

Abstract

Event Abstract Back to Event Investigation of microscopic diffusion anisotropy reveals microstructural changes in normal aging of the human brain Marco Lawrenz1 and Jürgen Finsterbusch1* 1 University Medical Center Hamburg-Eppendorf, Department of Systems Neuroscience, Germany Introduction Many investigations on white matter (WM) microstructure rely on DTI. Its FA also depends on the macroscopic fiber orientation distribution. Recently introduced microscopic diffusion anisotropy measures derived from double diffusion encoding (DDE) experiments for the long mixing time regime (e.g. MA index, [1]) overcome this limitation being independent of the orientation distributions of axons and fibers. Even in a WM region-of-interest (ROI) that appeared isotropic in a DTI experiment, anisotropic diffusion could be detected [2]. Recent studies showed that MA measurements are feasible in human brain in vivo [3]. Results Mean values of MA and FA and their variation in groups of young (< 33 y) and old (> 60 y), healthy volunteers have been determined. Mean values in selected ROIs show differences in both measures between groups. Statistical analysis of MA and FA maps revealed large regions with significant age-related changes. FA changes were found to be in line with the literature. FA exhibited reduced values in deep WM but increased in several GM ROIs such as the putamen and the thalamus. In contrast, MA decreased globally with only few exceptions. MA revealed age-related changes also in regions with insignificant FA in particular in regions known to contain fiber crossings (Fig 1). Being more consistent between different white matter ROIs and less dependent on the fiber orientation distribution than FA, MA may provide a more direct and more sensitive access to changes of tissue microstructure. The determination of the MA in cortical gray matter regions (Fig. 2) is more challenging since the modulation is typically smaller than in WM. To circumvent confounding partial volume effects with WM, a gray matter DDE variant has been used involving an adiabatic inversion recovery pulse that aims to null the WM signal in order to minimize the partial volume effect [4]. [1] Lawrenz M et al., J. Magn. Reson. 202, 43, (2010) [2] Lawrenz M et al., Magn. Reson. Med. 69, 1072 (2013) [3] Lawrenz M et al., Magn. Reson. Med. 73, 773 (2015) [4] Lawrenz M et al., Proc. ISMRM 2014, p. 2638 Fig. 1: t-maps (p<0.001) for age-related changes of the MA and FA. Most regions with significant FA change also reveal significant MA change, but MA changes can also be seen in regions without FA changes. Fig. 2: MA map of cortical gray matter. Figure 1 Figure 2 Figure 3 Keywords: Diffusion, MRI, dMRI, multidimensional, diffusion encoding Conference: New dimensions in diffusion encoding, Fjälkinge, Sweden, 11 Jan - 14 Jan, 2016. Presentation Type: Oral presentation Topic: New Dimensions in Diffusion Encoding Citation: Lawrenz M and Finsterbusch J (2016). Investigation of microscopic diffusion anisotropy reveals microstructural changes in normal aging of the human brain. Front. Phys. Conference Abstract: New dimensions in diffusion encoding. doi: 10.3389/conf.FPHY.2016.01.00024 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 07 Jul 2016; Published Online: 07 Jul 2016. * Correspondence: Dr. Jürgen Finsterbusch, University Medical Center Hamburg-Eppendorf, Department of Systems Neuroscience, Hamburg, 20246, Germany, j.finsterbusch@uke.uni-hamburg.de Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Marco Lawrenz Jürgen Finsterbusch Google Marco Lawrenz Jürgen Finsterbusch Google Scholar Marco Lawrenz Jürgen Finsterbusch PubMed Marco Lawrenz Jürgen Finsterbusch Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.