Diffusion MRI has recently been used with detailed models to probe tissue microstructure. Much of this work has been performed ex vivo with powerful scanner hardware, to gain sensitivity to parameters such as axon radius. By contrast, performing microstructure imaging on clinical scanners is extremely challenging

Aboitiz

Alexander

Andersson

Assaf

Barazany

Basser

Callaghan

Clayden

Drobnjak

Dyrby

Eddelbuettel

Feinberg

Gelderen

Hall

Huang

Ianuş

Koch

Lawrenz

Le Bihan

McNab

Neuman

Nilsson

Price

R Core Team. R

Reese

Roberts

Setsompop

Shemesh

Siow

Stanisz

Stejskal

Swain

Szafer

Zhang

English

PubMed

PURPOSE:Diffusion MRI has recently been used with detailed models to probe tissue microstructure. Much of this work has been performed ex vivo with powerful scanner hardware, to gain sensitivity to parameters such as axon radius. By contrast, performing microstructure imaging on clinical scanners is extremely challenging.METHODS:We use an optimized dual spin-echo diffusion protocol, and a Bayesian fitting approach, to obtain reproducible contrast (histogram overlap of up to 92%) in estimated maps of axon radius index in healthy adults at a modest, widely-available gradient strength (35 mT m -1). A key innovation is the use of influential priors.RESULTS:We demonstrate that our priors can improve precision in axon radius estimates-a 7-fold reduction in voxelwise coefficient of variation in vivo-without significant bias. Our results may reflect true axon radius differences between white matter regions, but this interpretation should be treated with caution due to the complexity of the tissue relative to our model.CONCLUSIONS:Some sensitivity to relatively large axons (3-15 μm) may be available at clinical field and gradient strengths. Future applications at higher gradient strength will benefit from the favorable eddy current properties of the dual spin-echo sequence, and greater precision available with suitable priors

Clayden, J.

Nagy, Z.

Weiskopf, N. 

Alexander, D.

Clark, C.

MPG.PuRe

Microstructural parameter estimation in vivo using diffusion MRI and structured prior information

Jonathan D. Clayden

Zoltan Nagy

Nikolaus Weiskopf

Daniel C. Alexander

Chris A. Clark

Crossref

Magnetic Resonance in Medicine

Clayden, JD

Nagy, Z

Weiskopf, N

Alexander, DC

Clark, CA

UCL Discovery

A general framework for experiment design in diusion MRI and its application to measuring direct tissue-microstructure features.

Active imaging with dual spin-echo diusion MRI.

Alexander D.C.(2011b). Axondiametermappinginthepresence of orientation dispersion with diusion MRI. NeuroImage 56:1301–1315. 14µm 0 10

An analytical model of restricted diusion in bovine optic nerve. Magnetic Resonance in Medicine 37:103–111.

Axcaliber: A method for measuring axon diameter distribution from diusion MRI. Magnetic Resonance in Medicine 59(6):1347–1354.

Axon diameter mapping in crossing ﬁbers with diusion MRI.

Axon radius estimation with oscillating gradient spin echo (OGSE) diusion MRI. Diusion Fundamentals 18(1):1–6.

Color indexing.

Compartment size estimation with double wave vector diusionweighted imaging.

Composite hindered and restricted model of diusion (CHARMED) MR imaging of the human brain.

Contrast and stability of the axon diameter index from microstructure imaging with diusion MRI.

Convergence and parameter choice for Monte-Carlo simulations of diffusion MRI.

Dependence of temporal diusion spectra on microstructural properties of biological tissues.

Double-wavevector diusion-weighting experiments with multiple concatenations at long mixing times.

Eddy current-nulled diusion weighting.

Estimation of pore size in a microstructure phantom using the optimised gradient waveform diusion weighted NMR sequence.

Estimation of the eective self-diusion tensor from the NMR spin echo.

Evaluation of restricted diusion in cylinders. Phosphocreatine in rabbit leg muscle.

Fast and robust measurement of microstructural dimensions using temporal diusion spectroscopy.

Fiber composition of the human corpus callosum.

Gaussian phase distribution approximations for oscillating gradient spin echo diusion MRI.

In vivo measurement of axon diameter distribution in the corpus callosum of rat brain.

Looking into the functional architecture of the brain with diusion MRI.

Maximum a posteriori estimation of diusion tensor parameters using a Rician noise model: Why, how and but.

Measuring small compartmental dimensions with low-q angular double-PGSE NMR: The eect of experimental parameters on signal decay.

Microscopic and compartment shape anisotropies in gray and white matter revealed by angular bipolar double-PFG MR.

On the eects of a varied diffusion time in vivo: Is the diusion in white matter restricted? Magnetic Resonance Imaging 27:176–187.

Open-source diusion-MRI reconstruction and processing.

Optimizing gradient waveforms for microstructure sensitivity in diusion-weighted MR.

Orientationally invariant indices of axon diameter and density from diusion MRI.

Principles of nuclear magnetic resonance microscopy.

Pulsed-ﬁeld gradient nuclear magnetic resonance as a tool for studying translational diffusion: Part 1. Basic theory. Concepts in Magnetic Resonance 9A(5):299–336.

Pushing the limits of in vivo diusion MRI for the Human Connectome Project. NeuroImage 80:220–233.

R: A language and environment for statistical computing. R Foundation for Statistical Computing,

Rcpp: Seamless RandC++Integration.

RcppArmadillo: Accelerating R with high-performance C++ linear algebra.

Reduction of eddy-current-induced distortion in diusion MRI using a twice-refocused spin echo.

Spin diusion measurements: spin echoes in the presence of a timedependent ﬁeld gradient.

Spin echo of spins diusing in a bounded medium.

The Human Connectome Project and beyond: initial applications of 300 mT/m gradients.

The impact of gradient strength on in vivo diusion MRI estimates of axon diameter.

The importance of axonal undulation in diusion MR measurements: A Monte Carlo simulation study.

Theoretical model for water diusion in tissues.

Tissue perfusion in humans studied by Fourier velocity distribution, line scan, and echo-planar imaging.

TractoR: Magnetic resonance imaging and tractography with R.

Undulating and crossing axons in the corpus callosum may explain the overestimation of axon diameters with ActiveAx.

Weak convergence and optimal scaling of random walk Metropolis algorithms.

Microstructural parameter estimation in vivo using diffusion MRI and structured prior information.

PURPOSE: Diffusion MRI has recently been used with detailed models to probe tissue microstructure. Much of this work has been performed ex vivo with powerful scanner hardware, to gain sensitivity to parameters such as axon radius. By contrast, performing microstructure imaging on clinical scanners is extremely challenging. METHODS: We use an optimized dual spin-echo diffusion protocol, and a Bayesian fitting approach, to obtain reproducible contrast (histogram overlap of up to 92%) in estimated maps of axon radius index in healthy adults at a modest, widely-available gradient strength (35 mT m -1). A key innovation is the use of influential priors. RESULTS: We demonstrate that our priors can improve precision in axon radius estimates-a 7-fold reduction in voxelwise coefficient of variation in vivo-without significant bias. Our results may reflect true axon radius differences between white matter regions, but this interpretation should be treated with caution due to the complexity of the tissue relative to our model. CONCLUSIONS: Some sensitivity to relatively large axons (3-15 μm) may be available at clinical field and gradient strengths. Future applications at higher gradient strength will benefit from the favorable eddy current properties of the dual spin-echo sequence, and greater precision available with suitable priors

Weiskopf, N.

Microstructural parameter estimation in vivo using diffusion MRI and structured prior information.

Abstract

Similar works

Full text

Available Versions

MPG.PuRe

Crossref

UCL Discovery

MPG.PuRe