Orientationally-averaged diffusion-attenuated magnetic resonance signal for locally-anisotropic diffusion

Diffusion-attenuated MR signal for heterogeneous media has been represented as a sum of signals from anisotropic Gaussian sub-domains to the extent that this approximation is permissible. Any effect of macroscopic (global or ensemble) anisotropy in the signal can be removed by averaging the signal v...

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Bibliographic Details
Published in:Scientific reports 2019-03, Vol.9 (1), p.4899-4899, Article 4899
Main Authors: Herberthson, Magnus, Yolcu, Cem, Knutsson, Hans, Westin, Carl-Fredrik, Özarslan, Evren
Format: Article
Language:English
Subjects:
59/57
639/166/985
639/705/1041
639/766/25
Anisotropy
Diffusion
Diffusion Magnetic Resonance Imaging
Eigenvalues
Humanities and Social Sciences
Humans
Laplace transforms
Magnetic resonance spectroscopy
Mathematics
Models, Theoretical
multidisciplinary
NMR
Nuclear magnetic resonance
Science
Science (multidisciplinary)
White Matter - diagnostic imaging
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Summary:Diffusion-attenuated MR signal for heterogeneous media has been represented as a sum of signals from anisotropic Gaussian sub-domains to the extent that this approximation is permissible. Any effect of macroscopic (global or ensemble) anisotropy in the signal can be removed by averaging the signal values obtained by differently oriented experimental schemes. The resulting average signal is identical to what one would get if the micro-domains are isotropically (e.g., randomly) distributed with respect to orientation, which is the case for “powdered” specimens. We provide exact expressions for the orientationally-averaged signal obtained via general gradient waveforms when the microdomains are characterized by a general diffusion tensor possibly featuring three distinct eigenvalues. This extends earlier results which covered only axisymmetric diffusion as well as measurement tensors. Our results are expected to be useful in not only multidimensional diffusion MR but also solid-state NMR spectroscopy due to the mathematical similarities in the two fields.
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-019-41317-8