Comparative Systematic Analysis of Gray Matter Biophysical Models on a Public Dataset.
Paper
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The authors' code
Python · 1 line · 0 B · Apache-2.0
__init__.py at commit 1ed059d, under Apache-2.0 · at the source
Overview
- Department of Radiology Lausanne University Hospital (CHUV) Lausanne Switzerland
- Faculty of Biology and Medicine University of Lausanne Lausanne Switzerland
- School of Psychology University of Auckland Auckland New Zealand
- Athinoula A. Martinos Center for Biomedical Imaging Charlestown Massachusetts USA
- Department of Radiology, Massachusetts General Hospital Harvard Medical School Boston Massachusetts USA
Abstract
Purpose: Biophysical models of diffusion tailored to characterize gray matter (GM) microstructure are gaining traction in the neuroimaging community. NEXI, SMEX, SANDI, and SANDIX represent recent efforts to account for different microstructural features, such as soma contributions and inter‐compartment exchange, in the diffusion MRI (dMRI) signal. The purpose of this work is to provide a comparative evaluation of these four GM diffusion models.
Methods: A comparative analysis of NEXI, SMEX, SANDI, and SANDIX was performed using a single, publicly available in vivo human dataset, the Connectome Diffusion Microstructure Dataset (CDMD), acquired with two diffusion times. Cortical microstructure metrics were estimated in 26 healthy subjects using the open‐source Gray Matter Swiss Knife toolbox, and goodness of fit, anatomical patterns, and consistency with previous studies were evaluated.
Results: CDMD data yielded GM parameter estimates consistent with values reported in previous studies across all four models. NEXI and SMEX produced similar cortical anatomical patterns, with consistent regional distributions across diffusion times. Goodness of fit varied across models, with NEXI showing the best fit, followed by SMEX, and finally SANDIX. SANDI parameter estimates showed strong dependence on diffusion‐time selection and fitting algorithm.
Conclusion: This retrospective cross‐model analysis establishes the feasibility of estimating exchange models from only two diffusion times and highlights trade‐offs in biological specificity, model complexity, and fitting robustness, which are critical considerations when selecting a model for future clinical and research applications.
Reproduced under the paper's license (CC BY), from the paper cited above.
Repository
Its files are read in the Code ↔ Paper reader above.
QuentinUhl/graymatter_swissknife
1ed059d44a4f4951d6106c1b2df6105d38e5697c, 6 August 2025Availability: 1 check, the latest on 27 September 2026: the link answers
- 27 September 2026: the link answers
71 files
- src/
__init__.py , Python, 1 line - src/
graymatter_swissknife/ , Python, 4 lines__about__.py - src/
graymatter_swissknife/ , Python, 8 lines__init__.py - src/
graymatter_swissknife/ , Python, 5 lines__main__.py - src/
graymatter_swissknife/ , Python, 76 linescompute_powder_average.p y - src/
graymatter_swissknife/ , Python, 227 linesdeprecated/ estimate_model_folded_no rmal.py - src/
graymatter_swissknife/ , Python, 299 linesestimate_model.py - src/
graymatter_swissknife/ , Python, 288 linesestimate_model_noiseless .py - src/
graymatter_swissknife/ , Python, 302 linesestimate_model_preinitia lized.py - src/
graymatter_swissknife/ , Python, 2 linesmodels/ GEM/ __init__.py - src/
graymatter_swissknife/ , Python, 1 linemodels/ GEM/ functions/ __init__.py - src/
graymatter_swissknife/ , Python, 462 linesmodels/ GEM/ functions/ scipy_gem.py - src/
graymatter_swissknife/ , Python, 61 linesmodels/ GEM/ gem.py - src/
graymatter_swissknife/ , Python, 84 linesmodels/ GEM/ gem_rm.py - src/
graymatter_swissknife/ , Python, 7 linesmodels/ NEXI/ __init__.py - src/
graymatter_swissknife/ , Python, 823 linesmodels/ NEXI/ functions/ scipy_nexi.py - src/
graymatter_swissknife/ , Python, 233 linesmodels/ NEXI/ functions/ scipy_nexi_dot.py - src/
graymatter_swissknife/ , Python, 444 linesmodels/ NEXI/ functions/ scipy_smex.py - src/
graymatter_swissknife/ , Python, 68 linesmodels/ NEXI/ nexi.py - src/
graymatter_swissknife/ , Python, 62 linesmodels/ NEXI/ nexi_dot.py - src/
graymatter_swissknife/ , Python, 82 linesmodels/ NEXI/ nexi_dot_rm.py - src/
graymatter_swissknife/ , Python, 87 linesmodels/ NEXI/ nexi_foldednormal.py - src/
graymatter_swissknife/ , Python, 87 linesmodels/ NEXI/ nexi_rm.py - src/
graymatter_swissknife/ , Python, 61 linesmodels/ NEXI/ smex.py - src/
graymatter_swissknife/ , Python, 86 linesmodels/ NEXI/ smex_rm.py - src/
graymatter_swissknife/ , Python, 2 linesmodels/ SANDI/ __init__.py - src/
graymatter_swissknife/ , Python, 1 linemodels/ SANDI/ functions/ __init__.py - src/
graymatter_swissknife/ , Python, 97 linesmodels/ SANDI/ functions/ scipy_sandi.py - src/
graymatter_swissknife/ , Python, 71 linesmodels/ SANDI/ sandi.py - src/
graymatter_swissknife/ , Python, 77 linesmodels/ SANDI/ sandi_rm.py - src/
graymatter_swissknife/ , Python, 2 linesmodels/ SANDIX/ __init__.py - src/
graymatter_swissknife/ , Python, 1 linemodels/ SANDIX/ functions/ __init__.py - src/
graymatter_swissknife/ , Python, 148 linesmodels/ SANDIX/ functions/ scipy_sandix.py - src/
graymatter_swissknife/ , Python, 63 linesmodels/ SANDIX/ sandix.py - src/
graymatter_swissknife/ , Python, 82 linesmodels/ SANDIX/ sandix_rm.py - src/
graymatter_swissknife/ , Python, 6 linesmodels/ __init__.py - src/
graymatter_swissknife/ , Python, 18 linesmodels/ find_model.py - src/
graymatter_swissknife/ , Python, 24 linesmodels/ microstructure_models.py - src/
graymatter_swissknife/ , Python, 2 linesmodels/ noise/ __init__.py - src/
graymatter_swissknife/ , Python, 61 linesmodels/ noise/ folded_normal_mean.py - src/
graymatter_swissknife/ , Python, 89 linesmodels/ noise/ rice_mean.py - src/
graymatter_swissknife/ , Python, 2 linesmodels/ parameters/ __init__.py - src/
graymatter_swissknife/ , Python, 41 linesmodels/ parameters/ acq_parameters.py - src/
graymatter_swissknife/ , Python, 49 linesmodels/ parameters/ mist_parameters.py - src/
graymatter_swissknife/ , Python, 67 linesmodels/ parameters/ save_parameters.py - src/
graymatter_swissknife/ , Python, 1 linemodels/ struct_functions/ __init__.py - src/
graymatter_swissknife/ , Python, 232 linesmodels/ struct_functions/ scipy_cylinder.py - src/
graymatter_swissknife/ , Python, 402 linesmodels/ struct_functions/ scipy_sphere.py - src/
graymatter_swissknife/ , Python, 1 linenls/ __init__.py - src/
graymatter_swissknife/ , Python, 192 linesnls/ gridsearch.py - src/
graymatter_swissknife/ , Python, 145 linesnls/ nls.py - src/
graymatter_swissknife/ , Python, 1 linepowderaverage/ __init__.py - src/
graymatter_swissknife/ , Python, 302 linespowderaverage/ powderaverage.py - src/
graymatter_swissknife/ , Python, 16 linesxgboost/ apply_xgboost_model.py - src/
graymatter_swissknife/ , Python, 108 linesxgboost/ define_xgboost_forward_m odel.py - src/
graymatter_swissknife/ , Python, 125 linesxgboost/ define_xgboost_model.py - src/
graymatter_swissknife/ , Python, 55 linesxgboost/ generate_dataset.py - src/
graymatter_swissknife/ , Python, 131 linesxgboost/ xgboost_powered_gridsear ch.py - src/
graymatter_swissknife/ , Python, 168 linesxgboost/ xgboost_powered_nls.py - tests/
__init__.py , Python, 3 lines - tests/
graymatter_swissknife/ , Python, 76 linesgenerate_phantom.py - tests/
graymatter_swissknife/ , Python, 71 linesmodels/ struct_functions/ test_scipy_sphere.py - tests/
graymatter_swissknife/ , Python, 68 linesmodels/ test_folded_normal_mean. py - tests/
graymatter_swissknife/ , Python, 139 linesmodels/ test_nexi_functions.py - tests/
graymatter_swissknife/ , Python, 68 linesmodels/ test_rician_mean.py - tests/
graymatter_swissknife/ , Python, 55 linespowderaverage/ test_powderaverage.py - tests/
graymatter_swissknife/ , Python, 61 linestest_estimate_model.py - tests/
graymatter_swissknife/ , Python, 51 linestest_estimate_model_nois eless.py - tests/
graymatter_swissknife/ , Python, 19 linesxgboost/ test_generate_dataset.py - LICENSE, License, 201 lines
- README.md, Text, 144 lines
The paper's code and data availability statement is in the Data section.
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Data
Datasets cited
- figshare:c5315474, at figshare; found in “Data Availability Statement”
Data Availability Statement
The CDMD dataset used in this study is publicly available at https://
Reproduced under the paper's license (CC BY), 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, 11 MeSH terms, 2 funders, 47 references.
Cite
This paper
Mezzano, S., Uhl, Q., Pavan, T., Nguyen‐Duc, J., Lee, H., Huang, S., & Jelescu, I. (2026). Comparative Systematic Analysis of Gray Matter Biophysical Models on a Public Dataset. Magnetic resonance in medicine, 96(5), 2278-2291. https://
BibTeX
@article{mezzano2026comp
author = {Mezzano, Santiago and Uhl, Quentin and Pavan, Tommaso and Nguyen‐Duc, Jasmine and Lee, Hansol and Huang, Susie and Jelescu, Ileana},
title = {{Comparative Systematic Analysis of Gray Matter Biophysical Models on a Public Dataset}},
journal = {Magnetic resonance in medicine},
year = {2026},
month = jul,
volume = {96},
number = {5},
pages = {2278--2291},
publisher = {Wiley},
issn = {0740-3194},
doi = {10.1002/
url = {https://
pmid = {42464030},
pmcid = {PMC13527255}
}
RIS
TY - JOUR
AU - Mezzano, Santiago
AU - Uhl, Quentin
AU - Pavan, Tommaso
AU - Nguyen‐Duc, Jasmine
AU - Lee, Hansol
AU - Huang, Susie
AU - Jelescu, Ileana
TI - Comparative Systematic Analysis of Gray Matter Biophysical Models on a Public Dataset
T2 - Magnetic resonance in medicine
J2 - Magn Reson Med
PY - 2026
DA - 2026/
VL - 96
IS - 5
SP - 2278
EP - 2291
SN - 0740-3194
PB - Wiley
DO - 10.1002/
UR - https://
LA - en
ER -
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