Raffelt, DA;
Tournier, J-D;
Smith, RE;
Vaughan, DN;
Jackson, G;
Ridgway, GR;
Connelly, A;
(2017)
Investigating white matter fibre density and morphology using fixel-based analysis.
NeuroImage
, 144
(Part A)
pp. 58-73.
10.1016/j.neuroimage.2016.09.029.
Preview |
Text
Raffelt_Investigating_white_matter_fibre.pdf Download (4MB) | Preview |
Abstract
Voxel-based analysis of diffusion MRI data is increasingly popular. However, most white matter voxels contain contributions from multiple fibre populations (often referred to as crossing fibres), and therefore voxel-averaged quantitative measures (e.g. fractional anisotropy) are not fibre-specific and have poor interpretability. Using higher-order diffusion models, parameters related to fibre density can be extracted for individual fibre populations within each voxel (‘fixels’), and recent advances in statistics enable the multi-subject analysis of such data. However, investigating within-voxel microscopic fibre density alone does not account for macroscopic differences in the white matter morphology (e.g. the calibre of a fibre bundle). In this work, we introduce a novel method to investigate the latter, which we call fixel-based morphometry (FBM). To obtain a more complete measure related to the total number of white matter axons, information from both within-voxel microscopic fibre density and macroscopic morphology must be combined. We therefore present the FBM method as an integral piece within a comprehensive fixel-based analysis framework to investigate measures of fibre density, fibre-bundle morphology (cross-section), and a combined measure of fibre density and cross-section. We performed simulations to demonstrate the proposed measures using various transformations of a numerical fibre bundle phantom. Finally, we provide an example of such an analysis by comparing a clinical patient group to a healthy control group, which demonstrates that all three measures provide distinct and complementary information. By capturing information from both sources, the combined fibre density and cross-section measure is likely to be more sensitive to certain pathologies and more directly interpretable.
| Type: | Article |
|---|---|
| Title: | Investigating white matter fibre density and morphology using fixel-based analysis |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1016/j.neuroimage.2016.09.029 |
| Publisher version: | https://doi.org/10.1016/j.neuroimage.2016.09.029 |
| Language: | English |
| Additional information: | Copyright © 2016 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). |
| Keywords: | Diffusion; MRI; Fixel; Fibre; Density; Cross-section |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/1524973 |
Archive Staff Only
 |
View Item |
