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Liquid crystal phantom for validation of microscopic diffusion anisotropy measurements on clinical MRI systems
Author(s) -
Nilsson Markus,
Larsson Johan,
Lundberg Dan,
Szczepankiewicz Filip,
Witzel Thomas,
Westin CarlFredrik,
Bryskhe Karin,
Topgaard Daniel
Publication year - 2018
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.26814
Subject(s) - imaging phantom , anisotropy , nuclear magnetic resonance , diffusion mri , fractional anisotropy , diffusion , thermal diffusivity , magnetic resonance imaging , spin echo , relaxation (psychology) , materials science , physics , optics , medicine , radiology , quantum mechanics , thermodynamics
Purpose To develop a phantom for validating MRI pulse sequences and data processing methods to quantify microscopic diffusion anisotropy in the human brain. Methods Using a liquid crystal consisting of water, detergent, and hydrocarbon, we designed a 0.5‐L spherical phantom showing the theoretically highest possible degree of microscopic anisotropy. Data were acquired on the Connectome scanner using echo‐planar imaging signal readout and diffusion encoding with axisymmetric b ‐tensors of varying magnitude, anisotropy, and orientation. The mean diffusivity, fractional anisotropy (FA), and microscopic FA (µFA) parameters were estimated. Results The phantom was observed to have values of mean diffusivity similar to brain tissue, and relaxation times compatible with echo‐planar imaging echo times on the order of 100 ms. The estimated values of µFA were at the theoretical maximum of 1.0, whereas the values of FA spanned the interval from 0.0 to 0.8 as a result of varying orientational order of the anisotropic domains within each voxel. Conclusions The proposed phantom can be manufactured by mixing three widely available chemicals in volumes comparable to a human head. The acquired data are in excellent agreement with theoretical predictions, showing that the phantom is ideal for validating methods for measuring microscopic diffusion anisotropy on clinical MRI systems. Magn Reson Med 79:1817–1828, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.