Global optimization of default phases for parallel transmit coils for ultra-high-field cardiac MRI.

The development of novel multiple-element transmit-receive arrays is an essential factor for improving B1+ field homogeneity in cardiac MRI at ultra-high magnetic field strength (B0 > = 7.0T). One of the key steps in the design and fine-tuning of such arrays during the development process is find...

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Autores principales:	Maxim Terekhov, Ibrahim A Elabyad, Laura M Schreiber
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/cc6886e8a1004bafa5b10e63c7db1f54
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spelling	oai:doaj.org-article:cc6886e8a1004bafa5b10e63c7db1f542021-12-02T20:18:35ZGlobal optimization of default phases for parallel transmit coils for ultra-high-field cardiac MRI.1932-620310.1371/journal.pone.0255341https://doaj.org/article/cc6886e8a1004bafa5b10e63c7db1f542021-01-01T00:00:00Zhttps://doi.org/10.1371/journal.pone.0255341https://doaj.org/toc/1932-6203The development of novel multiple-element transmit-receive arrays is an essential factor for improving B1+ field homogeneity in cardiac MRI at ultra-high magnetic field strength (B0 > = 7.0T). One of the key steps in the design and fine-tuning of such arrays during the development process is finding the default driving phases for individual coil elements providing the best possible homogeneity of the combined B1+-field that is achievable without (or before) subject-specific B1+-adjustment in the scanner. This task is often solved by time-consuming (brute-force) or by limited efficiency optimization methods. In this work, we propose a robust technique to find phase vectors providing optimization of the B1-homogeneity in the default setup of multiple-element transceiver arrays. The key point of the described method is the pre-selection of starting vectors for the iterative solver-based search to maximize the probability of finding a global extremum for a cost function optimizing the homogeneity of a shaped B1+-field. This strategy allows for (i) drastic reduction of the computation time in comparison to a brute-force method and (ii) finding phase vectors providing a combined B1+-field with homogeneity characteristics superior to the one provided by the random-multi-start optimization approach. The method was efficiently used for optimizing the default phase settings in the in-house-built 8Tx/16Rx arrays designed for cMRI in pigs at 7T.Maxim TerekhovIbrahim A ElabyadLaura M SchreiberPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 16, Iss 8, p e0255341 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Maxim Terekhov Ibrahim A Elabyad Laura M Schreiber Global optimization of default phases for parallel transmit coils for ultra-high-field cardiac MRI.
description	The development of novel multiple-element transmit-receive arrays is an essential factor for improving B1+ field homogeneity in cardiac MRI at ultra-high magnetic field strength (B0 > = 7.0T). One of the key steps in the design and fine-tuning of such arrays during the development process is finding the default driving phases for individual coil elements providing the best possible homogeneity of the combined B1+-field that is achievable without (or before) subject-specific B1+-adjustment in the scanner. This task is often solved by time-consuming (brute-force) or by limited efficiency optimization methods. In this work, we propose a robust technique to find phase vectors providing optimization of the B1-homogeneity in the default setup of multiple-element transceiver arrays. The key point of the described method is the pre-selection of starting vectors for the iterative solver-based search to maximize the probability of finding a global extremum for a cost function optimizing the homogeneity of a shaped B1+-field. This strategy allows for (i) drastic reduction of the computation time in comparison to a brute-force method and (ii) finding phase vectors providing a combined B1+-field with homogeneity characteristics superior to the one provided by the random-multi-start optimization approach. The method was efficiently used for optimizing the default phase settings in the in-house-built 8Tx/16Rx arrays designed for cMRI in pigs at 7T.
format	article
author	Maxim Terekhov Ibrahim A Elabyad Laura M Schreiber
author_facet	Maxim Terekhov Ibrahim A Elabyad Laura M Schreiber
author_sort	Maxim Terekhov
title	Global optimization of default phases for parallel transmit coils for ultra-high-field cardiac MRI.
title_short	Global optimization of default phases for parallel transmit coils for ultra-high-field cardiac MRI.
title_full	Global optimization of default phases for parallel transmit coils for ultra-high-field cardiac MRI.
title_fullStr	Global optimization of default phases for parallel transmit coils for ultra-high-field cardiac MRI.
title_full_unstemmed	Global optimization of default phases for parallel transmit coils for ultra-high-field cardiac MRI.
title_sort	global optimization of default phases for parallel transmit coils for ultra-high-field cardiac mri.
publisher	Public Library of Science (PLoS)
publishDate	2021
url	https://doaj.org/article/cc6886e8a1004bafa5b10e63c7db1f54
work_keys_str_mv	AT maximterekhov globaloptimizationofdefaultphasesforparalleltransmitcoilsforultrahighfieldcardiacmri AT ibrahimaelabyad globaloptimizationofdefaultphasesforparalleltransmitcoilsforultrahighfieldcardiacmri AT lauramschreiber globaloptimizationofdefaultphasesforparalleltransmitcoilsforultrahighfieldcardiacmri
_version_	1718374313091923968

Global optimization of default phases for parallel transmit coils for ultra-high-field cardiac MRI.

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