Comparative analysis of signal models for microscopic fractional anisotropy estimation using q-space trajectory encoding
Microscopic diffusion anisotropy imaging using diffusion-weighted MRI and multidimensional diffusion encoding is a promising method for quantifying clinically and scientifically relevant microstructural properties of neural tissue. Several methods for estimating microscopic fractional anisotropy (µF...
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doaj-a3d3e66b2ea24ede9d974e5690d2a27f2021-09-05T04:39:43ZengElsevierNeuroImage1095-95722021-11-01242118445Comparative analysis of signal models for microscopic fractional anisotropy estimation using q-space trajectory encodingLeevi Kerkelä0Fabio Nery1Ross Callaghan2Fenglei Zhou3Noemi G. Gyori4Filip Szczepankiewicz5Marco Palombo6Geoff J.M. Parker7Hui Zhang8Matt G. Hall9Chris A. Clark10UCL Great Ormond Street Institute of Child Health, University College London, London, UK; Corresponding author. Developmental Imaging & Biophysics Section, UCL Great Ormond Street Institute of Child Health, 30 Guilford Street, WC1N 1EH, London, UK.UCL Great Ormond Street Institute of Child Health, University College London, London, UKUCL Centre for Medical Image Computing, University College London, London, UKUCL Centre for Medical Image Computing, University College London, London, UK; UCL School of Pharmacy, University College London, London, UKUCL Centre for Medical Image Computing, University College London, London, UK; UCL Great Ormond Street Institute of Child Health, University College London, London, UKDepartment of Radiology, Brigham and Women’s Hospital, Boston, Massachusetts, US; Harvard Medical School, Boston, Massachusetts, US; Clinical Sciences Lund, Lund University, Lund, SwedenUCL Centre for Medical Image Computing, University College London, London, UKUCL Centre for Medical Image Computing, University College London, London, UK; Bioxydyn Limited, Manchester, UK; UCL Queen Square Institute of Neurology, University College London, London, UKUCL Centre for Medical Image Computing, University College London, London, UKUCL Great Ormond Street Institute of Child Health, University College London, London, UK; National Physical Laboratory, Teddington, UKUCL Great Ormond Street Institute of Child Health, University College London, London, UKMicroscopic diffusion anisotropy imaging using diffusion-weighted MRI and multidimensional diffusion encoding is a promising method for quantifying clinically and scientifically relevant microstructural properties of neural tissue. Several methods for estimating microscopic fractional anisotropy (µFA), a normalized measure of microscopic diffusion anisotropy, have been introduced but the differences between the methods have received little attention thus far. In this study, the accuracy and precision of µFA estimation using q-space trajectory encoding and different signal models were assessed using imaging experiments and simulations. Three healthy volunteers and a microfibre phantom were imaged with five non-zero b-values and gradient waveforms encoding linear and spherical b-tensors. Since the ground-truth µFA was unknown in the imaging experiments, Monte Carlo random walk simulations were performed using axon-mimicking fibres for which the ground truth was known. Furthermore, parameter bias due to time-dependent diffusion was quantified by repeating the simulations with tuned waveforms, which have similar power spectra, and with triple diffusion encoding, which, unlike q-space trajectory encoding, is not based on the assumption of time-independent diffusion. The truncated cumulant expansion of the powder-averaged signal, gamma-distributed diffusivities assumption, and q-space trajectory imaging, a generalization of the truncated cumulant expansion to individual signals, were used to estimate µFA. The gamma-distributed diffusivities assumption consistently resulted in greater µFA values than the second order cumulant expansion, 0.1 greater when averaged over the whole brain. In the simulations, the generalized cumulant expansion provided the most accurate estimates. Importantly, although time-dependent diffusion caused significant overestimation of µFA using all the studied methods, the simulations suggest that the resulting bias in µFA is less than 0.1 in human white matter.http://www.sciencedirect.com/science/article/pii/S1053811921007199Diffusion MRIMicroscopic fractional anisotropyMultidimensional diffusion encodingSignal model |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Leevi Kerkelä Fabio Nery Ross Callaghan Fenglei Zhou Noemi G. Gyori Filip Szczepankiewicz Marco Palombo Geoff J.M. Parker Hui Zhang Matt G. Hall Chris A. Clark |
spellingShingle |
Leevi Kerkelä Fabio Nery Ross Callaghan Fenglei Zhou Noemi G. Gyori Filip Szczepankiewicz Marco Palombo Geoff J.M. Parker Hui Zhang Matt G. Hall Chris A. Clark Comparative analysis of signal models for microscopic fractional anisotropy estimation using q-space trajectory encoding NeuroImage Diffusion MRI Microscopic fractional anisotropy Multidimensional diffusion encoding Signal model |
author_facet |
Leevi Kerkelä Fabio Nery Ross Callaghan Fenglei Zhou Noemi G. Gyori Filip Szczepankiewicz Marco Palombo Geoff J.M. Parker Hui Zhang Matt G. Hall Chris A. Clark |
author_sort |
Leevi Kerkelä |
title |
Comparative analysis of signal models for microscopic fractional anisotropy estimation using q-space trajectory encoding |
title_short |
Comparative analysis of signal models for microscopic fractional anisotropy estimation using q-space trajectory encoding |
title_full |
Comparative analysis of signal models for microscopic fractional anisotropy estimation using q-space trajectory encoding |
title_fullStr |
Comparative analysis of signal models for microscopic fractional anisotropy estimation using q-space trajectory encoding |
title_full_unstemmed |
Comparative analysis of signal models for microscopic fractional anisotropy estimation using q-space trajectory encoding |
title_sort |
comparative analysis of signal models for microscopic fractional anisotropy estimation using q-space trajectory encoding |
publisher |
Elsevier |
series |
NeuroImage |
issn |
1095-9572 |
publishDate |
2021-11-01 |
description |
Microscopic diffusion anisotropy imaging using diffusion-weighted MRI and multidimensional diffusion encoding is a promising method for quantifying clinically and scientifically relevant microstructural properties of neural tissue. Several methods for estimating microscopic fractional anisotropy (µFA), a normalized measure of microscopic diffusion anisotropy, have been introduced but the differences between the methods have received little attention thus far. In this study, the accuracy and precision of µFA estimation using q-space trajectory encoding and different signal models were assessed using imaging experiments and simulations. Three healthy volunteers and a microfibre phantom were imaged with five non-zero b-values and gradient waveforms encoding linear and spherical b-tensors. Since the ground-truth µFA was unknown in the imaging experiments, Monte Carlo random walk simulations were performed using axon-mimicking fibres for which the ground truth was known. Furthermore, parameter bias due to time-dependent diffusion was quantified by repeating the simulations with tuned waveforms, which have similar power spectra, and with triple diffusion encoding, which, unlike q-space trajectory encoding, is not based on the assumption of time-independent diffusion. The truncated cumulant expansion of the powder-averaged signal, gamma-distributed diffusivities assumption, and q-space trajectory imaging, a generalization of the truncated cumulant expansion to individual signals, were used to estimate µFA. The gamma-distributed diffusivities assumption consistently resulted in greater µFA values than the second order cumulant expansion, 0.1 greater when averaged over the whole brain. In the simulations, the generalized cumulant expansion provided the most accurate estimates. Importantly, although time-dependent diffusion caused significant overestimation of µFA using all the studied methods, the simulations suggest that the resulting bias in µFA is less than 0.1 in human white matter. |
topic |
Diffusion MRI Microscopic fractional anisotropy Multidimensional diffusion encoding Signal model |
url |
http://www.sciencedirect.com/science/article/pii/S1053811921007199 |
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