Prevalence of white matter pathways coming into a single white matter voxel orientation: The bottleneck issue in tractography
Schilling, Kurt G.; Tax, Chantal M.W.; Rheault, Francois; Landman, Bennett A.; Anderson, Adam W.; Descoteaux, Maxime; Petit, Laurent
(2022) Human Brain Mapping, volume 43, issue 4, pp. 1196 - 1213
(Article)
Abstract
Characterizing and understanding the limitations of diffusion MRI fiber tractography is a prerequisite for methodological advances and innovations which will allow these techniques to accurately map the connections of the human brain. The so-called “crossing fiber problem” has received tremendous attention and has continuously triggered the community to develop novel
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approaches for disentangling distinctly oriented fiber populations. Perhaps an even greater challenge occurs when multiple white matter bundles converge within a single voxel, or throughout a single brain region, and share the same parallel orientation, before diverging and continuing towards their final cortical or sub-cortical terminations. These so-called “bottleneck” regions contribute to the ill-posed nature of the tractography process, and lead to both false positive and false negative estimated connections. Yet, as opposed to the extent of crossing fibers, a thorough characterization of bottleneck regions has not been performed. The aim of this study is to quantify the prevalence of bottleneck regions. To do this, we use diffusion tractography to segment known white matter bundles of the brain, and assign each bundle to voxels they pass through and to specific orientations within those voxels (i.e. fixels). We demonstrate that bottlenecks occur in greater than 50-70% of fixels in the white matter of the human brain. We find that all projection, association, and commissural fibers contribute to, and are affected by, this phenomenon, and show that even regions traditionally considered “single fiber voxels” often contain multiple fiber populations. Together, this study shows that a majority of white matter presents bottlenecks for tractography which may lead to incorrect or erroneous estimates of brain connectivity or quantitative tractography (i.e., tractometry), and underscores the need for a paradigm shift in the process of tractography and bundle segmentation for studying the fiber pathways of the human brain.
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Keywords: bottleneck, crossing fibers, fiber pathways, tractography, tractometry, white matter, Humans, Image Processing, Computer-Assisted/methods, Neural Pathways/anatomy & histology, Adult, White Matter/anatomy & histology, Diffusion Tensor Imaging/methods, Clinical Neurology, Neurology, Radiological and Ultrasound Technology, Radiology Nuclear Medicine and imaging, Anatomy, Research Support, Non-U.S. Gov't, Journal Article, Research Support, N.I.H., Extramural
ISSN: 1065-9471
Publisher: Wiley-Liss Inc.
Note: Funding Information: Data were provided [in part] by the Human Connectome Project, WU‐Minn Consortium (Principal Investigators: David Van Essen and Kamil Ugurbil; 1U54MH091657) funded by the 16 NIH Institutes and Centers that support the NIH Blueprint for Neuroscience Research; and by the McDonnell Center for Systems Neuroscience at Washington University. All resulting voxel‐wise and fixel‐wise bundle overlaps, for both TractSeg and Recobundles, is available upon request. Funding Information: Institutional Research Chair in Neuroinformatics and NSERC Discovery; Dutch Research Council (NWO), Grant/Award Number: 17331; Sir Henry Wellcome Fellowship, Grant/Award Number: 215944/Z/19/Z; National Center for Research Resources, Grant/Award Number: UL1 RR024975‐01; ViSE/VICTR, Grant/Award Number: VR3029; National Institutes of Health, Grant/Award Numbers: T32EB001628, R01EB017230 Funding information Funding Information: This work was supported by the National Institutes of Health under award numbers R01EB017230 and T32EB001628, and in part by ViSE/VICTR VR3029 and the National Center for Research Resources, Grant UL1 RR024975‐01. Chantal M. W. Tax was supported by a Sir Henry Wellcome Fellowship (215944/Z/19/Z), and a Veni grant (17331) from the Dutch Research Council (NWO). Maxime Descoteaux was supported by the Institutional Research Chair in Neuroinformatics and NSERC Discovery. Publisher Copyright: © 2021 The Authors. Human Brain Mapping published by Wiley Periodicals LLC. © 2021 The Authors. Human Brain Mapping published by Wiley Periodicals LLC.
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