Corbin, N;
Acosta-Cabronero, J;
Malik, SJ;
Callaghan, MF;
(2019)
Robust 3D Bloch-Siegert based B 1 + mapping using multi-echo general linear modeling.
Magnetic Resonance in Medicine
10.1002/mrm.27851.
(In press).
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Abstract
PURPOSE: Quantitative MRI applications, such as mapping the T1 time of tissue, puts high demands on the accuracy and precision of transmit field ( B 1 + ) estimation. A candidate approach to satisfy these requirements exploits the difference in phase induced by the Bloch-Siegert frequency shift (BSS) of 2 acquisitions with opposite off-resonance frequency radiofrequency pulses. Interleaving these radiofrequency pulses ensures robustness to motion and scanner drifts; however, here we demonstrate that doing so also introduces a bias in the B 1 + estimates. THEORY AND METHODS: It is shown here by means of simulation and experiments that the amplitude of the error depends on MR pulse sequence parameters, such as repetition time and radiofrequency spoiling increment, but more problematically, on the intrinsic properties, T1 and T2 , of the investigated tissue. To solve these problems, a new approach to BSS-based B 1 + estimation that uses a multi-echo acquisition and a general linear model to estimate the correct BSS-induced phase is presented. RESULTS: In line with simulations, phantom and in vivo experiments confirmed that the general linear model-based method removed the dependency on tissue properties and pulse sequence settings. CONCLUSION: The general linear model-based method is recommended as a more accurate approach to BSS-based B 1 + mapping.
| Type: | Article |
|---|---|
| Title: | Robust 3D Bloch-Siegert based B 1 + mapping using multi-echo general linear modeling |
| Location: | United States |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1002/mrm.27851 |
| Publisher version: | https://doi.org/10.1002/mrm.27851 |
| Language: | English |
| Additional information: | This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ |
| Keywords: | B 1 + mapping, Bloch-Siegert shift, GLM, RF spoiling, interleaved acquisition, multi-echo readout |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > UCL Queen Square Institute of Neurology UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > UCL Queen Square Institute of Neurology > Imaging Neuroscience |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10078988 |
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