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Diffusion MRI in the cortex of the brain : Reducing partial volume effects from CSF and white matter in the mean diffusivity using high b-values and spherical b-tensor encoding

Säll, Cornelia LU ; Spotorno, Nicola LU ; Sundgren, Pia C. LU orcid ; van Westen, Danielle LU orcid ; Westin, Carl Fredrik ; Szczepankiewicz, Filip LU orcid and Nilsson, Markus LU (2025) In Magnetic Resonance in Medicine 94(3). p.1166-1181
Abstract

Purpose: The mean diffusivity (MD) is sensitive to the microstructure of the cortex. However, partial volume effects with CSF and white matter (WM) may obscure pathology-related alterations. This work investigates both existing approaches and a novel approach for reducing partial volume effects. Theory and Methods: A bias in MD arises due to partial volume effects, higher-order terms, and the noise floor in magnitude data. We propose to reduce this bias by using high b-value encoding to limit partial volume effects with CSF, spherical b-tensor encoding to reduce the influence of higher-order terms, and super-resolution acquisition and reconstruction to suppress the noise floor. This approach was investigated, along with established... (More)

Purpose: The mean diffusivity (MD) is sensitive to the microstructure of the cortex. However, partial volume effects with CSF and white matter (WM) may obscure pathology-related alterations. This work investigates both existing approaches and a novel approach for reducing partial volume effects. Theory and Methods: A bias in MD arises due to partial volume effects, higher-order terms, and the noise floor in magnitude data. We propose to reduce this bias by using high b-value encoding to limit partial volume effects with CSF, spherical b-tensor encoding to reduce the influence of higher-order terms, and super-resolution acquisition and reconstruction to suppress the noise floor. This approach was investigated, along with established approaches (inversion recovery and free water elimination) for reducing partial volume effects, using simulations and in vivo data. Results: High b-value diffusion MRI with spherical b-tensor encoding reduced partial volume effects with CSF relative to conventional diffusion MRI. Maximum errors decreased from 0.51 to 0.01 μm2/ms in simulations. In vivo, the median absolute deviation of cortical MD decreased from 0.17 to 0.06 μm2/ms, whereas the median decreased slightly from 0.77 to 0.73 μm2/ms. The other methods yielded bias from either CSF, WM, or model assumptions. Conclusion: The mean diffusivity of the cortex can be mapped in high precision with reduced influence of partial volume effects with CSF and WM matter using high b-values and spherical b-tensor encoding and super-resolution reconstruction.

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author
; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
cortex, diffusion MRI, high b-values, mean diffusivity, partial volume effects, spherical b-tensor encoding
in
Magnetic Resonance in Medicine
volume
94
issue
3
pages
16 pages
publisher
John Wiley & Sons Inc.
external identifiers
  • pmid:40468575
  • scopus:105007622639
ISSN
0740-3194
DOI
10.1002/mrm.30552
language
English
LU publication?
yes
id
9a9bc36a-3806-4de8-8fa3-95587e215e69
date added to LUP
2025-10-31 10:16:00
date last changed
2025-10-31 10:17:00
@article{9a9bc36a-3806-4de8-8fa3-95587e215e69,
  abstract     = {{<p>Purpose: The mean diffusivity (MD) is sensitive to the microstructure of the cortex. However, partial volume effects with CSF and white matter (WM) may obscure pathology-related alterations. This work investigates both existing approaches and a novel approach for reducing partial volume effects. Theory and Methods: A bias in MD arises due to partial volume effects, higher-order terms, and the noise floor in magnitude data. We propose to reduce this bias by using high b-value encoding to limit partial volume effects with CSF, spherical b-tensor encoding to reduce the influence of higher-order terms, and super-resolution acquisition and reconstruction to suppress the noise floor. This approach was investigated, along with established approaches (inversion recovery and free water elimination) for reducing partial volume effects, using simulations and in vivo data. Results: High b-value diffusion MRI with spherical b-tensor encoding reduced partial volume effects with CSF relative to conventional diffusion MRI. Maximum errors decreased from 0.51 to 0.01 μm<sup>2</sup>/ms in simulations. In vivo, the median absolute deviation of cortical MD decreased from 0.17 to 0.06 μm<sup>2</sup>/ms, whereas the median decreased slightly from 0.77 to 0.73 μm<sup>2</sup>/ms. The other methods yielded bias from either CSF, WM, or model assumptions. Conclusion: The mean diffusivity of the cortex can be mapped in high precision with reduced influence of partial volume effects with CSF and WM matter using high b-values and spherical b-tensor encoding and super-resolution reconstruction.</p>}},
  author       = {{Säll, Cornelia and Spotorno, Nicola and Sundgren, Pia C. and van Westen, Danielle and Westin, Carl Fredrik and Szczepankiewicz, Filip and Nilsson, Markus}},
  issn         = {{0740-3194}},
  keywords     = {{cortex; diffusion MRI; high b-values; mean diffusivity; partial volume effects; spherical b-tensor encoding}},
  language     = {{eng}},
  number       = {{3}},
  pages        = {{1166--1181}},
  publisher    = {{John Wiley & Sons Inc.}},
  series       = {{Magnetic Resonance in Medicine}},
  title        = {{Diffusion MRI in the cortex of the brain : Reducing partial volume effects from CSF and white matter in the mean diffusivity using high b-values and spherical b-tensor encoding}},
  url          = {{http://dx.doi.org/10.1002/mrm.30552}},
  doi          = {{10.1002/mrm.30552}},
  volume       = {{94}},
  year         = {{2025}},
}