AxTract: Toward microstructure informed tractography
Hum. Brain Mapp.. 2017-08-02; 38(11): 5485-5500
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1. Hum Brain Mapp. 2017 Nov;38(11):5485-5500. doi: 10.1002/hbm.23741. Epub 2017 Aug
AxTract: Toward microstructure informed tractography.
Girard G(1)(2)(3), Daducci A(3)(4)(5), Petit L(6), Thiran JP(3)(5), Whittingstall
K(7)(8), Deriche R(2), Wassermann D(2), Descoteaux M(1)(3)(8).
(1)Sherbrooke Connectivity Imaging Lab, Computer Science Department, Faculty of
Science, Université de Sherbrooke, Sherbrooke, Canada.
(2)Project Team Athena, Inria Sophia Antipolis Méditerranée, Université Côte
d’Azur, Sophia Antipolis, France.
(3)Signal Processing Lab (LTS5), School of Engineering, École Polytechnique
Fédérale de Lausanne, Lausanne, Switzerland.
(4)Computer Science Department, University of Verona, Verona, Italy.
(5)Radiology Department, Centre Hospitalier Universitaire Vaudois and University
of Lausanne, Lausanne, Switzerland.
(6)Groupe d’Imagie Neurofonctionnelle, Institut des Maladies Neurodégénératives –
UMR 5293, CNRS, CEA University of Bordeaux, Bordeaux, France.
(7)Department of Diagnostic Radiology, Faculty of Medicine and Health Science,
Université de Sherbrooke, Sherbrooke, Canada.
(8)Sherbrooke Molecular Imaging Center (CIMS), Centre de Recherche CHUS
(CR-CHUS), Sherbrooke, Canada.
Diffusion-weighted (DW) magnetic resonance imaging (MRI) tractography has become
the tool of choice to probe the human brain’s white matter in vivo. However,
tractography algorithms produce a large number of erroneous streamlines (false
positives), largely due to complex ambiguous tissue configurations. Moreover, the
relationship between the resulting streamlines and the underlying white matter
microstructure characteristics remains poorly understood. In this work, we
introduce a new approach to simultaneously reconstruct white matter fascicles and
characterize the apparent distribution of axon diameters within fascicles. To
achieve this, our method, AxTract, takes full advantage of the recent development
DW-MRI microstructure acquisition, modeling, and reconstruction techniques. This
enables AxTract to separate parallel fascicles with different microstructure
characteristics, hence reducing ambiguities in areas of complex tissue
configuration. We report a decrease in the incidence of erroneous streamlines
compared to the conventional deterministic tractography algorithms on simulated
data. We also report an average increase in streamline density over 15 known
fascicles of the 34 healthy subjects. Our results suggest that microstructure
information improves tractography in crossing areas of the white matter.
Moreover, AxTract provides additional microstructure information along the
fascicle that can be studied alongside other streamline-based indices. Overall,
AxTract provides the means to distinguish and follow white matter fascicles using
their microstructure characteristics, bringing new insights into the white matter
organization. This is a step forward in microstructure informed tractography,
paving the way to a new generation of algorithms able to deal with intricate
configurations of white matter fibers and providing quantitative brain
connectivity analysis. Hum Brain Mapp 38:5485-5500, 2017. © 2017 Wiley
© 2017 Wiley Periodicals, Inc.
PMID: 28766853 [Indexed for MEDLINE]