UCL Discovery
UCL home » Library Services » Electronic resources » UCL Discovery

High angular resolution diffusion imaging with stimulated echoes: Compensation and correction in experiment design and analysis

Lundell, H; Dyrby, TB; Alexander, DC; (2014) High angular resolution diffusion imaging with stimulated echoes: Compensation and correction in experiment design and analysis. NMR in Biomedicine , 27 (8) pp. 918-925. 10.1002/nbm.3137. Green open access

[img]
Preview
PDF
nbm3137.pdf

Download (2MB)

Abstract

Stimulated echo acquisition mode (STEAM) diffusion MRI can be advantageous over pulsed-gradient spin-echo (PGSE) for diffusion times that are long compared with T. It therefore has potential for biomedical diffusion imaging applications at 7T and above where T is short. However, gradient pulses other than the diffusion gradients in the STEAM sequence contribute much greater diffusion weighting than in PGSE and lead to a disrupted experimental design. Here, we introduce a simple compensation to the STEAM acquisition that avoids the orientational bias and disrupted experiment design that these gradient pulses can otherwise produce. The compensation is simple to implement by adjusting the gradient vectors in the diffusion pulses of the STEAM sequence, so that the net effective gradient vector including contributions from diffusion and other gradient pulses is as the experiment intends. High angular resolution diffusion imaging (HARDI) data were acquired with and without the proposed compensation. The data were processed to derive standard diffusion tensor imaging (DTI) maps, which highlight the need for the compensation. Ignoring the other gradient pulses, a bias in DTI parameters from STEAM acquisition is found, due both to confounds in the analysis and the experiment design. Retrospectively correcting the analysis with a calculation of the full B matrix can partly correct for these confounds, but an acquisition that is compensated as proposed is needed to remove the effect entirely. © 2014 The Authors.

Type: Article
Title: High angular resolution diffusion imaging with stimulated echoes: Compensation and correction in experiment design and analysis
Open access status: An open access version is available from UCL Discovery
DOI: 10.1002/nbm.3137
Publisher version: http://dx.doi.org/10.1002/nbm.3137
Language: English
Additional information: © 2014 The Authors. NMR in Biomedicine published by John Wiley & Sons, Ltd. This is an open access article under the terms of the Creative Commons AttributionLicense, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Keywords: Diffusion MRI, Diffusion tensor imaging, HARDI, STEAM, Stimulated echo
UCL classification: UCL
UCL > Provost and Vice Provost Offices
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/1433768
Downloads since deposit
143Downloads
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item