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Towards unconstrained compartment modeling in white matter using diffusion-relaxation MRI with tensor-valued diffusion encoding

Lampinen, Björn LU ; Szczepankiewicz, Filip LU orcid ; Mårtensson, Johan LU ; van Westen, Danielle LU orcid ; Hansson, Oskar LU orcid ; Westin, Carl Fredrik and Nilsson, Markus LU (2020) In Magnetic Resonance in Medicine 84(3). p.1605-1623
Abstract

Purpose: To optimize diffusion-relaxation MRI with tensor-valued diffusion encoding for precise estimation of compartment-specific fractions, diffusivities, and T2 values within a two-compartment model of white matter, and to explore the approach in vivo. Methods: Sampling protocols featuring different b-values (b), b-tensor shapes (bΔ), and echo times (TE) were optimized using Cramér-Rao lower bounds (CRLB). Whole-brain data were acquired in children, adults, and elderly with white matter lesions. Compartment fractions, diffusivities, and T2 values were estimated in a model featuring two microstructural compartments represented by a “stick” and a “zeppelin.”. Results: Precise parameter estimates were... (More)

Purpose: To optimize diffusion-relaxation MRI with tensor-valued diffusion encoding for precise estimation of compartment-specific fractions, diffusivities, and T2 values within a two-compartment model of white matter, and to explore the approach in vivo. Methods: Sampling protocols featuring different b-values (b), b-tensor shapes (bΔ), and echo times (TE) were optimized using Cramér-Rao lower bounds (CRLB). Whole-brain data were acquired in children, adults, and elderly with white matter lesions. Compartment fractions, diffusivities, and T2 values were estimated in a model featuring two microstructural compartments represented by a “stick” and a “zeppelin.”. Results: Precise parameter estimates were enabled by sampling protocols featuring seven or more “shells” with unique b/bΔ/TE-combinations. Acquisition times were approximately 15 minutes. In white matter of adults, the “stick” compartment had a fraction of approximately 0.5 and, compared with the “zeppelin” compartment, featured lower isotropic diffusivities (0.6 vs. 1.3 μm2/ms) but higher T2 values (85 vs. 65 ms). Children featured lower “stick” fractions (0.4). White matter lesions exhibited high “zeppelin” isotropic diffusivities (1.7 μm2/ms) and T2 values (150 ms). Conclusions: Diffusion-relaxation MRI with tensor-valued diffusion encoding expands the set of microstructure parameters that can be precisely estimated and therefore increases their specificity to biological quantities.

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author
; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
brain microstructure, diffusion-relaxation MRI, Fisher information, tensor-valued diffusion encoding
in
Magnetic Resonance in Medicine
volume
84
issue
3
pages
19 pages
publisher
John Wiley & Sons Inc.
external identifiers
  • scopus:85080912830
  • pmid:32141131
ISSN
0740-3194
DOI
10.1002/mrm.28216
language
English
LU publication?
yes
id
cf529d6b-1f6d-4ee4-928f-12a8616feb45
date added to LUP
2020-03-19 15:39:14
date last changed
2024-06-12 10:32:09
@article{cf529d6b-1f6d-4ee4-928f-12a8616feb45,
  abstract     = {{<p>Purpose: To optimize diffusion-relaxation MRI with tensor-valued diffusion encoding for precise estimation of compartment-specific fractions, diffusivities, and T<sub>2</sub> values within a two-compartment model of white matter, and to explore the approach in vivo. Methods: Sampling protocols featuring different b-values (b), b-tensor shapes (b<sub>Δ</sub>), and echo times (TE) were optimized using Cramér-Rao lower bounds (CRLB). Whole-brain data were acquired in children, adults, and elderly with white matter lesions. Compartment fractions, diffusivities, and T<sub>2</sub> values were estimated in a model featuring two microstructural compartments represented by a “stick” and a “zeppelin.”. Results: Precise parameter estimates were enabled by sampling protocols featuring seven or more “shells” with unique b/b<sub>Δ</sub>/TE-combinations. Acquisition times were approximately 15 minutes. In white matter of adults, the “stick” compartment had a fraction of approximately 0.5 and, compared with the “zeppelin” compartment, featured lower isotropic diffusivities (0.6 vs. 1.3 μm<sup>2</sup>/ms) but higher T<sub>2</sub> values (85 vs. 65 ms). Children featured lower “stick” fractions (0.4). White matter lesions exhibited high “zeppelin” isotropic diffusivities (1.7 μm<sup>2</sup>/ms) and T<sub>2</sub> values (150 ms). Conclusions: Diffusion-relaxation MRI with tensor-valued diffusion encoding expands the set of microstructure parameters that can be precisely estimated and therefore increases their specificity to biological quantities.</p>}},
  author       = {{Lampinen, Björn and Szczepankiewicz, Filip and Mårtensson, Johan and van Westen, Danielle and Hansson, Oskar and Westin, Carl Fredrik and Nilsson, Markus}},
  issn         = {{0740-3194}},
  keywords     = {{brain microstructure; diffusion-relaxation MRI; Fisher information; tensor-valued diffusion encoding}},
  language     = {{eng}},
  number       = {{3}},
  pages        = {{1605--1623}},
  publisher    = {{John Wiley & Sons Inc.}},
  series       = {{Magnetic Resonance in Medicine}},
  title        = {{Towards unconstrained compartment modeling in white matter using diffusion-relaxation MRI with tensor-valued diffusion encoding}},
  url          = {{http://dx.doi.org/10.1002/mrm.28216}},
  doi          = {{10.1002/mrm.28216}},
  volume       = {{84}},
  year         = {{2020}},
}