Dependence of the Extra-Cellular Diffusion Coefficient on the Fractions of Neurites and Cell Bodies in Gray Matter.
Overview
- Radiology, Athinoula A. Martinos Center for Biomedical Imaging Massachusetts General Hospital Charlestown Massachusetts USA
- Harvard Medical School Boston Massachusetts USA
- A.I. Virtanen Institute for Molecular Sciences University of Eastern Finland Kuopio Finland
- Center for Advanced Imaging Innovation and Research (CAI2R), Department of Radiology New York University School of Medicine New York New York USA
Abstract
Purpose: The dependence of the long‐time (tortuosity) limit of the extra‐cellular diffusivity on the intra‐cellular volume fraction is of fundamental importance for microstructure modeling. While such dependencies have been explored for the white matter, the tortuosity limit in gray matter is unknown due to complex cell composition and geometry. Here we rationalize and validate numerically the analytical relation between the extra‐cellular diffusivity and intra‐cellular fractions of cell bodies (somas) and neurites.
Methods: The tortuosity relation for extra‐cellular diffusivity qualitatively follows from effective medium theory, coarse‐grained by diffusion outside somas (spheres) and neurites (cylinders), respectively. This problem is equivalent to finding the overall conductivity in a medium of grains in a matrix, with methodology dating back to the 19th century. We extend the effective medium methodology to populations of impermeable spheres and randomly oriented cylinders with various volume fractions, yielding closed‐form expressions corroborated by Monte Carlo simulations.
Results: We establish the power‐law scaling of the extra‐cellular diffusivity with the volume fractions of the extra‐soma and extra‐neurite spaces. We further evaluate the proposed framework using simulations in realistic tissue geometries, and by applying it to in vivo MRI data.
Conclusion: Theory and simulations relate extra‐cellular tortuosity to soma and neurite fractions, thereby offering a diffusion MRI protocol design optimized for in vivo assessment of soma size and soma/
Reproduced under the paper's license (CC BY-NC), from the paper cited above.
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Data
Datasets cited
- doi:10.5061/
dryad.36h28 , at Dryad; found in “Data Availability Statement” - doi:10.6084/
m9.figshare.c.5315474 , at figshare; found in “Data Availability Statement”
Data Availability Statement
The SBEM dataset was obtained from the publicly available repository (https://
Reproduced under the paper's license (CC BY-NC), from the paper cited above.
Versions
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Version 2, 28 September 2026
- Publisher: n/a → Wiley
Version 1, 27 September 2026: the first record
Recorded: type, language, journal, volume, issue, pages, dates, 7 authors, 4 keywords, 10 MeSH terms, 6 funders, 69 references.
Cite
This paper
Lee, H., Abdollahzadeh, A., Lee, H., Coronado‐Leija, R., Fieremans, E., Huang, S. Y., & Novikov, D. S. (2026). Dependence of the Extra-Cellular Diffusion Coefficient on the Fractions of Neurites and Cell Bodies in Gray Matter. Magnetic resonance in medicine, 96(5), 2426-2439. https://
BibTeX
@article{lee2026dependen
author = {Lee, Hong‐Hsi and Abdollahzadeh, Ali and Lee, Hansol and Coronado‐Leija, Ricardo and Fieremans, Els and Huang, Susie Y. and Novikov, Dmitry S.},
title = {{Dependence of the Extra-Cellular Diffusion Coefficient on the Fractions of Neurites and Cell Bodies in Gray Matter}},
journal = {Magnetic resonance in medicine},
year = {2026},
month = jun,
volume = {96},
number = {5},
pages = {2426--2439},
publisher = {Wiley},
issn = {0740-3194},
doi = {10.1002/
url = {https://
pmid = {42365425},
pmcid = {PMC13527277}
}
RIS
TY - JOUR
AU - Lee, Hong‐Hsi
AU - Abdollahzadeh, Ali
AU - Lee, Hansol
AU - Coronado‐Leija, Ricardo
AU - Fieremans, Els
AU - Huang, Susie Y.
AU - Novikov, Dmitry S.
TI - Dependence of the Extra-Cellular Diffusion Coefficient on the Fractions of Neurites and Cell Bodies in Gray Matter
T2 - Magnetic resonance in medicine
J2 - Magn Reson Med
PY - 2026
DA - 2026/
VL - 96
IS - 5
SP - 2426
EP - 2439
SN - 0740-3194
PB - Wiley
DO - 10.1002/
UR - https://
LA - en
ER -
CSL-JSON
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