Estimating the axon diameter from intra-axonal water diffusion with arbitrary gradient waveforms: Resolution limit in parallel and dispersed fibers

Abstract

Event Abstract Back to Event Estimating the axon diameter from intra-axonal water diffusion with arbitrary gradient waveforms: Resolution limit in parallel and dispersed fibers Markus Nilsson1* 1 Lund University, Lund University Bioimaging Center, Sweden Estimation of axon diameter from intra-axonal water diffusion may provide a valuable tool for non-invasive studies of brain connectivity. Techniques for axon diameter estimation have been developed on NMR spectrometers, and the feasibility demonstrated on fixated nerve tissue samples. Recently, attempts have been made to translate such techniques to clinical MRI scanners. The amplitudes of the gradients are, however, lower at clinical MRI scanners. For this reason accurate estimation of axon diameters in the human brain becomes challenging. The purpose of this study was to develop a framework to estimate the resolution limit, which we define as the diameter below which axons of different sizes cannot be told apart. Since there is a growing interest in using diffusion encoding techniques that go beyong the single diffusion encoding (SDE) experiment, we present a generalized framework that can predict the resolution limit regardless of the gradient waveform. The framework can be applied to understand the time dependence of SDE, double diffusio encoding, as well as more complex waveforms. We employed the framework to optimize gradient waveforms to minimize the resolution limit. The results show that for parallel fibers, the SDE experiment is optimal. In the presence of orientation dispersion, however, multiple diffusion encodings were optimal. The resolution limit was found to be between 2 and 4 micrometers, depending on maximal gradient amplitude and the level of orientation dispersion. 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: Nilsson M (2016). Estimating the axon diameter from intra-axonal water diffusion with arbitrary gradient waveforms: Resolution limit in parallel and dispersed fibers. Front. Phys. Conference Abstract: New dimensions in diffusion encoding. doi: 10.3389/conf.FPHY.2016.01.00006 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. Markus Nilsson, Lund University, Lund University Bioimaging Center, Lund, 221 85, Sweden, markus.nilsson@med.lu.se 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 Markus Nilsson Google Markus Nilsson Google Scholar Markus Nilsson PubMed Markus Nilsson 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.