Diffusion MRI/NMR at high gradients: new challenges and perspectives
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1
CNRS - Ecole Polytechnique, Laboratory of Condensed Matter Physics, France
The relation between the microstructure and the diffusion MRI
signal has been intensively studied by using either the narrow
pulse approximation or small gradient perturbative approaches.
In order to understand the physical mechanism of the dMRI signal
formation at high gradients, one needs to resort to non-perturbative
approaches. Extending the seminal work by Stoller, Happer and Dyson,
we present an analytical solution of the Bloch-Torrey equation for
one-dimensional diffusion across multiple semi-permeable barriers.
We investigate how the diffusive exchange across a semi-permeable
barrier modifies the non-Gaussian stretched-exponential behavior
of the pulsed-gradient spin-echo (PGSE) signal in this localization
regime. Moreover, we explore the transition between the localization
regime at low permeability and the Gaussian regime at high
permeability.
High gradients are suitable to spatially localize the contribution
of the nuclei near the barrier and to enhance the sensitivity of
the PGSE signal to the barrier permeability. The main focus of the
talk will be on new physical features of this non-Gaussian behavior,
and on the potential emergence of the localization regime in twoand
three-dimensional domains.
Reference:
D. S. Grebenkov, Exploring diffusion across permeable barriers at
high
gradients. II. Localization regime, J. Magn. Reson. 248, 164-176
(2014).
Keywords:
Diffusion,
MRI,
dMRI,
multidimensional,
diffusion encoding
Conference:
New dimensions in diffusion encoding, Fjälkinge, Sweden, 11 Jan - 14 Jan, 2016.
Presentation Type:
Oral presentation
Topic:
New Dimensions in Diffusion Encoding
Citation:
Grebenkov
D
(2016). Diffusion MRI/NMR at high gradients: new challenges and perspectives.
Front. Phys.
Conference Abstract:
New dimensions in diffusion encoding.
doi: 10.3389/conf.FPHY.2016.01.00022
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Received:
07 Jul 2016;
Published Online:
07 Jul 2016.
*
Correspondence:
Dr. Denis Grebenkov, CNRS - Ecole Polytechnique, Laboratory of Condensed Matter Physics, Palaiseau, F-91128, France, denis.grebenkov@polytechnique.edu