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Microanisotropy imaging : Quantification of microscopic diffusion anisotropy and orientational order parameter by diffusion MRI with magic-angle spinning of the q-vector

Lasič, Samo; Szczepankiewicz, Filip LU ; Eriksson, Stefanie LU ; Nilsson, Markus LU and Topgaard, Daniel LU (2014) In Frontiers of Physics 2. p.1-14
Abstract

Diffusion tensor imaging (DTI) is the method of choice for non-invasive investigations of the structure of human brain white matter (WM). The results are conventionally reported as maps of the fractional anisotropy (FA), which is a parameter related to microstructural features such as axon density, diameter, and myelination. The interpretation of FA in terms of microstructure becomes ambiguous when there is a distribution of axon orientations within the image voxel. In this paper, we propose a procedure for resolving this ambiguity by determining a new parameter, the microscopic fractional anisotropy (μFA), which corresponds to the FA without the confounding influence of orientation dispersion. In addition, we suggest a method for... (More)

Diffusion tensor imaging (DTI) is the method of choice for non-invasive investigations of the structure of human brain white matter (WM). The results are conventionally reported as maps of the fractional anisotropy (FA), which is a parameter related to microstructural features such as axon density, diameter, and myelination. The interpretation of FA in terms of microstructure becomes ambiguous when there is a distribution of axon orientations within the image voxel. In this paper, we propose a procedure for resolving this ambiguity by determining a new parameter, the microscopic fractional anisotropy (μFA), which corresponds to the FA without the confounding influence of orientation dispersion. In addition, we suggest a method for measuring the orientational order parameter (OP) for the anisotropic objects. The experimental protocol is capitalizing on a recently developed diffusion nuclear magnetic resonance (NMR) pulse sequence based on magic-angle spinning of the q-vector. Proof-of-principle experiments are carried out on microimaging and clinical MRI equipment using lyotropic liquid crystals and plant tissues as model materials with high μFA and low FA on account of orientation dispersion. We expect the presented method to be especially fruitful in combination with DTI and high angular resolution acquisition protocols for neuroimaging studies of gray and white matter.

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organization
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Contribution to journal
publication status
published
subject
keywords
Diffusion distribution, Fractional anisotropy, Microscopic diffusion anisotropy, Microscopic fractional anisotropy, Order parameter, Orientation dispersion, Q-MAS, Single shot isotropic diffusion weighting
in
Frontiers of Physics
volume
2
pages
14 pages
publisher
SP Higher Edication Press
external identifiers
  • scopus:84902573086
ISSN
2095-0462
DOI
10.3389/fphy.2014.00011
language
English
LU publication?
yes
id
18cacda8-84e8-4c88-a817-30927d92d0a8
date added to LUP
2016-04-11 09:32:43
date last changed
2017-07-02 04:49:54
@article{18cacda8-84e8-4c88-a817-30927d92d0a8,
  abstract     = {<p>Diffusion tensor imaging (DTI) is the method of choice for non-invasive investigations of the structure of human brain white matter (WM). The results are conventionally reported as maps of the fractional anisotropy (FA), which is a parameter related to microstructural features such as axon density, diameter, and myelination. The interpretation of FA in terms of microstructure becomes ambiguous when there is a distribution of axon orientations within the image voxel. In this paper, we propose a procedure for resolving this ambiguity by determining a new parameter, the microscopic fractional anisotropy (μFA), which corresponds to the FA without the confounding influence of orientation dispersion. In addition, we suggest a method for measuring the orientational order parameter (OP) for the anisotropic objects. The experimental protocol is capitalizing on a recently developed diffusion nuclear magnetic resonance (NMR) pulse sequence based on magic-angle spinning of the q-vector. Proof-of-principle experiments are carried out on microimaging and clinical MRI equipment using lyotropic liquid crystals and plant tissues as model materials with high μFA and low FA on account of orientation dispersion. We expect the presented method to be especially fruitful in combination with DTI and high angular resolution acquisition protocols for neuroimaging studies of gray and white matter.</p>},
  articleno    = {A011},
  author       = {Lasič, Samo and Szczepankiewicz, Filip and Eriksson, Stefanie and Nilsson, Markus and Topgaard, Daniel},
  issn         = {2095-0462},
  keyword      = {Diffusion distribution,Fractional anisotropy,Microscopic diffusion anisotropy,Microscopic fractional anisotropy,Order parameter,Orientation dispersion,Q-MAS,Single shot isotropic diffusion weighting},
  language     = {eng},
  pages        = {1--14},
  publisher    = {SP Higher Edication Press},
  series       = {Frontiers of Physics},
  title        = {Microanisotropy imaging : Quantification of microscopic diffusion anisotropy and orientational order parameter by diffusion MRI with magic-angle spinning of the q-vector},
  url          = {http://dx.doi.org/10.3389/fphy.2014.00011},
  volume       = {2},
  year         = {2014},
}