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Strong diffusion gradients allow the separation of intra- and extra-axonal gradient-echo signals in the human brain
2020
NeuroImage
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Voxelwise analysis of the signal evolution with respect to b-factor and acquisition delay using a microscopic model demonstrated differences in gradient echo signal evolution between the intra- and extra-axonal ...
Using D-FASE we can separately assess the evolution of the intra- and extra-axonal signals under the action of susceptibility effects, revealing differences in the behaviour in different fibre tracts. ...
Deployment of the diffusion filtering allowed us to separate the intra-and extra-axonal ASE signals unambiguously. ...
doi:10.1016/j.neuroimage.2020.116793
pmid:32335263
pmcid:PMC7613126
fatcat:ftgtdir6o5e3jctophwspb3oje
Multi-compartment microscopic diffusion imaging
2016
NeuroImage
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The aim is to estimate microscopic features specific to the intra-and extra-neurite compartments in nervous tissue unconfounded by the effects of fibre crossings and orientation dispersion, which are ubiquitous ...
in the brain. ...
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 ...
doi:10.1016/j.neuroimage.2016.06.002
pmid:27282476
pmcid:PMC5517363
fatcat:uu5poewaw5aaddve4f2h7tqurm
Microstructural imaging of the human brain with a 'super-scanner': 10 key advantages of ultra-strong gradients for diffusion MRI
2018
NeuroImage
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The diffusion-weighted MR signal is sensitive only to a window of restriction lengths and the bounds of that window depend strongly on the available gradient strength. ...
We finally discuss practical barriers in the use of ultra-strong gradients, and provide an outlook on the next generation of 'superscanners'. then discuss practical challenges in making use of such as ...
ACKNOWLEDGEMENTS: The UK National Facility for In Vivo MR Imaging of Human Tissue Microstructure was generously funded by the Engineering and Physical Sciences Research Council (EPSRC) (grant EP/M029778 ...
doi:10.1016/j.neuroimage.2018.05.047
pmid:29793061
fatcat:ozzxbxhol5em3cvnsgsjpzbc5i
Diffusion Signal in Magnetic Resonance Imaging: Origin and Interpretation in Neurosciences
2007
Biological Research
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The aim of this paper is to review hypotheses and actual knowledge on diffusion signal origin to provide assistance in the interpretation of diffusion MR images. ...
Diffusion signal does not come from two intra-or extracellular compartments, as was first assumed. ...
Diffusion signal is not bicompartmental, and not separated into intra-and extracellular compartments. ...
doi:10.4067/s0716-97602007000500003
fatcat:4k77efpahvfj5pmzja7ase3ye4
What dominates the time dependence of diffusion transverse to axons: Intra- or extra-axonal water?
2017
NeuroImage
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2017 pre-print arXiv:1707.09426v1 fatcat:62crwz7d5za4vjgudlm2ocras4
Here we resolve this debate in the human brain white matter. ...
This specific functional form is shown to originate from the extra-axonal space, and provides estimates of the fiber packing correlation length for axons in a bundle. ...
Research was supported by the National Institute of Neurological Disorders and Stroke of the NIH under award number R01NS088040. ...
doi:10.1016/j.neuroimage.2017.12.038
pmid:29253652
pmcid:PMC6004237
fatcat:vfp6ka2rsrebhgrhcdenm5bqba
Quantifying myelin in crossing fibers using diffusion‐prepared phase imaging: Theory and simulations
2021
Magnetic Resonance in Medicine
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The expected bias is estimated in the log g-ratio for reasonable in vivo acquisition parameters caused by eddy currents (~4%-10%), remaining extra-axonal signal (~15%), and gradients in the bulk off-resonance ...
In the human brain, white matter fiber pathways connecting different brain areas and carrying different functions often cross each other in the same voxel. ...
After diffusion-weighting the signal will be dominated by the intra-axonal water in axons perpendicular to the diffusion-weighting gradient. ...
doi:10.1002/mrm.28907
pmid:34254349
pmcid:PMC8581995
fatcat:ezfqp6e6hjazxcug3e3afqylbq
Intra- and extra-axonal axial diffusivities in the white matter: which one is faster?
[article]
2018
arXiv
pre-print
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A two-compartment model of diffusion in white matter, which accounts for intra- and extra-axonal spaces, is associated with two plausible mathematical scenarios: either the intra-axonal axial diffusivity ...
The aim of the present study was to use an intracerebroventricular injection of a gadolinium-based contrast agent to selectively reduce the extracellular water signal in the rat brain, and compare diffusion ...
This work was supported by the Centre d'Imagerie Bio-Médicale (CIBM) of the University of Lausanne (UNIL), the Swiss Federal Institute of Technology Lausanne (EPFL), the University of Geneva (UniGe), the ...
arXiv:1805.00391v2
fatcat:p74jje4safexpp7ugd45jl2yru
Imaging brain microstructure with diffusion MRI: practicality and applications
2017
NMR in Biomedicine
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. 14 O,P, A similar measure of the microscopic anisotropy from double diffusion encoding in a rat brain (O) 15 and a healthy human brain (P). 16 Q-T, Imaging myelin density. ...
It then reviews the evolution of mathematical and computational models that relate the diffusion MR signal to brain tissue microstructure, as well as the expanding areas of application. ...
, by allowing the intra-and extra-neurite compartments to have different intrinsic diffusivities and by not imposing the tortuosity
hindered and isotropic diffusion. ...
doi:10.1002/nbm.3841
pmid:29193413
fatcat:43pukyiwubb6bhsaey5gs3sizy
White Matter microstructural property decoding from gradient echo data using realistic white matter models
[article]
2020
bioRxiv
pre-print
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The multi-echo gradient echo (ME-GRE) magnetic resonance signal evolution in white matter has a strong dependence on the orientation of myelinated axons in respect to the main static field. ...
[Highlights] - A pipeline to generate realistic white matter models of arbitrary fiber volume fraction and g-ratio is presented; - We present a methodology to simulated the gradient echo signal from segmented ...
of the three compartments (intra-and extra-axonal water and myelin) to a ME-GRE signal. ...
doi:10.1101/2020.06.23.127258
fatcat:dhxlqxibl5h2rpyodbncqovkii
Including diffusion time dependence in the extra-axonal space improves in vivo estimates of axonal diameter and density in human white matter
2016
NeuroImage
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the human corpus callosum when modeling extra-axonal time-dependence. ...
Axonal density and diameter are two fundamental properties of brain white matter. Recently, advanced diffusion MRI techniques have made these two parameters accessible in vivo. ...
The Authors would like to thank Dr. D. Novikov and Prof. V. Kiselev for useful and interesting discussions and comments on earlier versions of this manuscript. ...
doi:10.1016/j.neuroimage.2016.01.047
pmid:26826514
pmcid:PMC4819719
fatcat:hccdo3uj55gavmts74gpcdls24
New insights about time-varying diffusivity and its estimation from diffusion MRI
2016
Magnetic Resonance in Medicine
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We present the explicit signal expressions for the case of single diffusion encoding and oscillating gradient spin-echo sequences. ...
There is also strong statistical evidence about time-varying diffusivity from the in vivo human data set. ...
Thus, separating the intra-and extra-axonal signals into two separate compartments might provide a more accurate estimation of the time-dependent diffusivity (from extra-axonal space). ...
doi:10.1002/mrm.26403
pmid:27611013
pmcid:PMC5344793
fatcat:vcvlbmtuu5gcvjsw5hjpvrzpfq
Simulation of changes in diffusion related to different pathologies at cellular level after traumatic brain injury
2015
Magnetic Resonance in Medicine
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Methods-A model with three compartments separated by permeable membranes was employed to represent the diffusion environment of water molecules in brain white matter. ...
The dynamic diffusion process was simulated with a Monte Carlo method using adjustable parameters of intraaxonal diffusivity, axon separation, glial cell volume fraction, and myelin sheath permeability ...
Acknowledgments We thank Sven Ekholm, Jeffrey Bazarian, and Eric Blackman for useful discussion during the course of the study. The authors would like to thank Dr. ...
doi:10.1002/mrm.25816
pmid:26256558
pmcid:PMC4769952
fatcat:6urthqu7evgfplci56dsoinp74
Multi-compartment diffusion MRI, T2 relaxometry and myelin water imaging as neuroimaging descriptors for anomalous tissue detection
[article]
2021
arXiv
pre-print
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Conventional MRI techniques such as T1-weighted and T2-weighted scans are generally used in the diagnosis and prognosis of the disease. ...
model in a cohort of MS patients and healthy controls. ...
grant 754462 to MP, the Swiss National Science Foundation grant PZ00P2 185814/1 to EJC-R and the Centre for Biomedical Imaging of the University of Lausanne, the Swiss Federal Institute of Technology ...
arXiv:2104.07502v1
fatcat:ylzpodfbmzhdxas2osr3kqiuwq
Single Encoding Diffusion MRI: A Probe to Brain Anisotropy
[chapter]
2021
Mathematics and Visualization
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AbstractThis chapter covers anisotropy in the context of probing microstructure of the human brain using single encoded diffusion MRI. ...
We will start by illustrating how diffusion MRI is a perfectly adapted technique to measure anisotropy in the human brain using water motion, followed by a biological presentation of human brain. ...
Acknowledgments This work was supported by the ERC-StG NeuroLang and the ANR/NSF NeuroRef grants. ...
doi:10.1007/978-3-030-56215-1_8
fatcat:ii25gxmmrbcsll3k5sbowhbumu
Estimating intra-axonal axial diffusivity in the presence of fibre orientation dispersion
[article]
2020
bioRxiv
pre-print
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In this work we use high b-value data to isolate the signal from the intra-axonal compartment and resolve any degeneracies with the extra-axonal compartment. ...
Our results in in vivo, human data show an intra-axonal axial diffusivity of ~2.3-3 μm2/ms, where 3 μm2/ms is the diffusivity of free water at 37°C. ...
In Figure 3c , both an intra-axonal and extra-axonal compartment contribute to the simulated diffusion signal. ...
doi:10.1101/2020.10.09.332700
fatcat:xsj3o24x7ncyddc74qctvqdeau
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