A Bore-Integrated Patch Antenna Array for Whole-Body Excitation in Ultra-High-Field Magnetic Resonance Imaging

The human body&#x2019;s ultra-high field magnetic resonance imaging suffers from the inhomogeneity of the radio frequency magnetic field <inline-formula> <tex-math notation="LaTeX">$B_{1}^{+}$ </tex-math></inline-formula> and the high-peak levels of SAR created...

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Main Authors: Svetlana S. Egorova, Nikolai A. Lisachenko, Egor I. Kretov, Yang Gao, Xiaotong Zhang, Stanislav B. Glybovski, Georgiy A. Solomakha
Format: Article
Language:English
Published: IEEE 2025-01-01
Series:IEEE Access
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Online Access:https://ieeexplore.ieee.org/document/10857326/
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author Svetlana S. Egorova
Nikolai A. Lisachenko
Egor I. Kretov
Yang Gao
Xiaotong Zhang
Stanislav B. Glybovski
Georgiy A. Solomakha
author_facet Svetlana S. Egorova
Nikolai A. Lisachenko
Egor I. Kretov
Yang Gao
Xiaotong Zhang
Stanislav B. Glybovski
Georgiy A. Solomakha
author_sort Svetlana S. Egorova
collection DOAJ
description The human body&#x2019;s ultra-high field magnetic resonance imaging suffers from the inhomogeneity of the radio frequency magnetic field <inline-formula> <tex-math notation="LaTeX">$B_{1}^{+}$ </tex-math></inline-formula> and the high-peak levels of SAR created in body tissues during transmission. Both issues are typically addressed in the research domain using a tight-fit local array of antenna elements attached to the body and driven with customized phases by multiple transmit channels. The same approach faces difficulties in fast and reliable SAR evaluation, precise positioning, and patient comfort in the clinical environment. Recently, a novel bore-integrated array of stripline antenna elements with substantial free space was introduced for whole-body imaging at 7 T, showing, however, insufficient transmission efficiency (the level of <inline-formula> <tex-math notation="LaTeX">$B_{1}^{+}$ </tex-math></inline-formula> at the unit input power). This work aims to improve the efficiency of the bore-integrated array configuration, which, unlike the tight-fit configuration, may be beneficial for prospective clinical workflow. After analyzing the proposed solutions, particularly the stripline antenna arrays, we found that one of the main limitations is the high level of losses within the array element. We propose using patch antenna elements separated by compact dual-loop decoupling resonators to overcome this limitation. Comparing the proposed elements with striplines in the same bore-integrated eight-channel configuration, we demonstrate numerically and experimentally on the bench a transmit efficiency improvement at least 3 times depending on the excitation mode. Furthermore, the proposed array is shown to overcome both the stripline array and volumetric TEM coil in terms of SAR efficiency approaching the level of the state-of-the-art tight-fit array of fractionated dipole antennas. Our results support the feasibility of integrating multichannel transmit array coils into the bore liner of a 7 T system while compromising transmit efficiency and providing competitive SAR efficiency.
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issn 2169-3536
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spelling doaj-art-130c032b41ec441da78ac20010159e462025-02-07T00:01:37ZengIEEEIEEE Access2169-35362025-01-0113231202313010.1109/ACCESS.2025.353636110857326A Bore-Integrated Patch Antenna Array for Whole-Body Excitation in Ultra-High-Field Magnetic Resonance ImagingSvetlana S. Egorova0Nikolai A. Lisachenko1Egor I. Kretov2Yang Gao3https://orcid.org/0000-0001-8915-5065Xiaotong Zhang4https://orcid.org/0000-0002-9197-1421Stanislav B. Glybovski5https://orcid.org/0000-0003-2908-3463Georgiy A. Solomakha6https://orcid.org/0000-0002-3024-0545School of Physics and Engineering, ITMO University, Saint Petersburg, RussiaSchool of Physics and Engineering, ITMO University, Saint Petersburg, RussiaSchool of Physics and Engineering, ITMO University, Saint Petersburg, RussiaHangzhou Institute of Technology, Xidian University, Hangzhou, ChinaCollege of Electrical Engineering, Zhejiang University, Hangzhou, ChinaSchool of Physics and Engineering, ITMO University, Saint Petersburg, RussiaSchool of Physics and Engineering, ITMO University, Saint Petersburg, RussiaThe human body&#x2019;s ultra-high field magnetic resonance imaging suffers from the inhomogeneity of the radio frequency magnetic field <inline-formula> <tex-math notation="LaTeX">$B_{1}^{+}$ </tex-math></inline-formula> and the high-peak levels of SAR created in body tissues during transmission. Both issues are typically addressed in the research domain using a tight-fit local array of antenna elements attached to the body and driven with customized phases by multiple transmit channels. The same approach faces difficulties in fast and reliable SAR evaluation, precise positioning, and patient comfort in the clinical environment. Recently, a novel bore-integrated array of stripline antenna elements with substantial free space was introduced for whole-body imaging at 7 T, showing, however, insufficient transmission efficiency (the level of <inline-formula> <tex-math notation="LaTeX">$B_{1}^{+}$ </tex-math></inline-formula> at the unit input power). This work aims to improve the efficiency of the bore-integrated array configuration, which, unlike the tight-fit configuration, may be beneficial for prospective clinical workflow. After analyzing the proposed solutions, particularly the stripline antenna arrays, we found that one of the main limitations is the high level of losses within the array element. We propose using patch antenna elements separated by compact dual-loop decoupling resonators to overcome this limitation. Comparing the proposed elements with striplines in the same bore-integrated eight-channel configuration, we demonstrate numerically and experimentally on the bench a transmit efficiency improvement at least 3 times depending on the excitation mode. Furthermore, the proposed array is shown to overcome both the stripline array and volumetric TEM coil in terms of SAR efficiency approaching the level of the state-of-the-art tight-fit array of fractionated dipole antennas. Our results support the feasibility of integrating multichannel transmit array coils into the bore liner of a 7 T system while compromising transmit efficiency and providing competitive SAR efficiency.https://ieeexplore.ieee.org/document/10857326/Patch antennasultra-high field MRItransmit efficiencySARRF shimming
spellingShingle Svetlana S. Egorova
Nikolai A. Lisachenko
Egor I. Kretov
Yang Gao
Xiaotong Zhang
Stanislav B. Glybovski
Georgiy A. Solomakha
A Bore-Integrated Patch Antenna Array for Whole-Body Excitation in Ultra-High-Field Magnetic Resonance Imaging
IEEE Access
Patch antennas
ultra-high field MRI
transmit efficiency
SAR
RF shimming
title A Bore-Integrated Patch Antenna Array for Whole-Body Excitation in Ultra-High-Field Magnetic Resonance Imaging
title_full A Bore-Integrated Patch Antenna Array for Whole-Body Excitation in Ultra-High-Field Magnetic Resonance Imaging
title_fullStr A Bore-Integrated Patch Antenna Array for Whole-Body Excitation in Ultra-High-Field Magnetic Resonance Imaging
title_full_unstemmed A Bore-Integrated Patch Antenna Array for Whole-Body Excitation in Ultra-High-Field Magnetic Resonance Imaging
title_short A Bore-Integrated Patch Antenna Array for Whole-Body Excitation in Ultra-High-Field Magnetic Resonance Imaging
title_sort bore integrated patch antenna array for whole body excitation in ultra high field magnetic resonance imaging
topic Patch antennas
ultra-high field MRI
transmit efficiency
SAR
RF shimming
url https://ieeexplore.ieee.org/document/10857326/
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