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Optimising oscillating waveform-shape for pore size sensitivity in diffusion-weighted MR

Drobnjak, I; Cruz, G; Alexander, DC; (2013) Optimising oscillating waveform-shape for pore size sensitivity in diffusion-weighted MR. Microporous and Mesoporous Materials , 178 11 - 14. 10.1016/j.micromeso.2013.03.004. Green open access

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Abstract

Optimising the shape of a generalised gradient waveform (GEN) in diffusion-weighted MR has been shown to, in theory, greatly increase sensitivity to pore size. The broad class of optimised shapes takes simple oscillatory forms. To speed up convergence of the optimisation, improve computation times and make the waveforms more practical, here we explore various oscillatory waveforms constructed from trapezoidal and sinusoidal shapes and compare their performance with the optimised GEN waveform. The oscillating waveforms are optimised to maximise sensitivity to parameters, such as axon radius, intra-cellular volume fraction and diffusion constants, of a simple white matter model. Simulation experiments find that all oscillating waveforms we tried perform significantly better than the original generalised waveform due to the improved convergence of the optimisation. Differences among the oscillating shapes however are very small and although a truncated sinusoidal waveform consistently gives the lowest cost function, no significant difference in the estimated model parameters was found. Therefore the simplest choice, i.e. the trapezoidal parametrisation, seems sufficient for most practical purposes.

Type: Article
Title: Optimising oscillating waveform-shape for pore size sensitivity in diffusion-weighted MR
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.micromeso.2013.03.004
Publisher version: http://dx.doi.org/10.1016/j.micromeso.2013.03.004
Language: English
Additional information: This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Keywords: Pore size, Diffusion MR, Oscillating gradients, Axon radius
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Computer Science
URI: https://discovery.ucl.ac.uk/id/eprint/1391207
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