ArticleNeuroImage2018
What dominates the time dependence of diffusion transverse to axons: Intra- or extra-axonal water?
Article in NeuroImage, 2018. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 53 papers.
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Who cites it
53 citing papers in PubMed, 83 citations in OpenAlex.
- Human In Vivo Validation of Frequency-Dependent QTI.Magnetic resonance in medicine · 2026Article
- Dependence of the Extra-Cellular Diffusion Coefficient on the Fractions of Neurites and Cell Bodies in Gray Matter.Magnetic resonance in medicine · 2026Article
- Evaluating the Influence of Injury-Induced Microstructural Variations on the Efficacy of a Diffusion MRI-Derived Axon Diameter Surrogate.Magnetic resonance in medicine · 2026Article
- Axon Diameter Mapping in the Living Human Brain with Ultra-High-Gradient Diffusion MRI at 500 mT/m Gradient Strength.Human brain mapping · 2026Article
- Complementary Sensitivity of Fixed-Time and Fixed-Oscillation Regimes to Exchange and Structural Disorder in the Human Brain Revealed Using Oscillating-Gradient Diffusion MRI With Ultra-Strong Gradients.Magnetic resonance in medicine · 2026Article
- Axon Diameter Mapping From Myelin Water Diffusion MRI.IEEE transactions on medical imaging · 2026Article
- Monte Carlo Assessment of Accuracy for Mean Kärger Model Water Exchange Rate Estimates From Diffusional Kurtosis Time Dependence.NMR in biomedicine · 2026Article
- Evaluation of diffusion time-dependent changes in radial diffusivity as a surrogate for axon diameter.Magnetic resonance in medicine · 2025Article
- Quasi-Diffusion Imaging: Application to Ultra-High b-Value and Time-Dependent Diffusion Images of Brain Tissue.NMR in biomedicine · 2025Article
- Revealing membrane integrity and cell size from diffusion kurtosis time dependence.Magnetic resonance in medicine · 2025Article
- Interplay between MRI-based axon diameter and myelination estimates in macaque and human brain.Imaging neuroscience (Cambridge, Mass.) · 2025Article
- Feasibility of brain intra-axonal microstructure imaging with ultrahigh B-encoding using MAGNUS ultra-high-performance gradients.Imaging neuroscience (Cambridge, Mass.) · 2025Article
- The effects of axonal beading and undulation on axonal diameter estimation from diffusion MRI: Insights from simulations in human axons segmented from three-dimensional electron microscopy.NMR in biomedicine · 2024Article
- A Method for In-Vivo Mapping of Axonal Diameter Distributions in the Human Brain Using Diffusion-Based Axonal Spectrum Imaging (AxSI).Neuroinformatics · 2023Article
- Novel insights into axon diameter and myelin content in late childhood and adolescence.Cerebral cortex (New York, N.Y. : 1991) · 2023Article
- Linear multi-scale modeling of diffusion MRI data: A framework for characterization of oriented structures across length scales.Human brain mapping · 2023Article
- Diffusion MRI with pulsed and free gradient waveforms: Effects of restricted diffusion and exchange.NMR in biomedicine · 2023Article
- Diffusion MRI signal cumulants and hepatocyte microstructure at fixed diffusion time: Insights from simulations, 9.4T imaging, and histology.Magnetic resonance in medicine · 2022Article
- Performance of orientation distribution function-fingerprinting with a biophysical multicompartment diffusion model.Magnetic resonance in medicine · 2022Article
- Mapping the human connectome using diffusion MRI at 300 mT/m gradient strength: Methodological advances and scientific impact.NeuroImage · 2022Review
Corrections and comments
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Authors and funding
3 authors at 1 institution in 1 country.
Funding
Abstract
Brownian motion of water molecules provides an essential length scale, the diffusion length, commensurate with cell dimensions in biological tissues. Measuring the diffusion coefficient as a function of diffusion time makes in vivo diffusion MRI uniquely sensitive to the cellular features about three orders of magnitude below imaging resolution. However, there is a longstanding debate, regarding which contribution - intra- or extra-cellular - is more relevant in the overall time-dependence of the MRI-derived diffusion metrics. Here we resolve this debate in the human brain white matter. By varying not just the diffusion time, but also the gradient pulse duration of a standard diffusion MRI sequence, we identify a functional form of the measured time-dependent diffusion coefficient transverse to white matter tracts in 10 healthy volunteers. This specific functional form is shown to originate from the extra-axonal space, and provides estimates of the fiber packing correlation length for axons in a bundle. Our results offer a metric for the outer axonal diameter, a promising candidate marker for demyelination in neurodegenerative diseases. From the methodological perspective, our analysis demonstrates how competing models, which describe different physics yet interpolate standard measurements equally well, can be distinguished based on their prediction for an independent "orthogonal" measurement.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.