Effect of radiofrequency shield diameter on signal-to-noise ratio at ultra-high field MRI

Bei Zhang; Gregor Adriany; Lance Delabarre; Jerahmie Radder; Russell Lagore; Brian Rutt; Qing X. Yang; Kamil Ugurbil; Riccardo Lattanzi

doi:10.1002/mrm.28670

Effect of radiofrequency shield diameter on signal-to-noise ratio at ultra-high field MRI

Bei Zhang, Gregor Adriany, Lance Delabarre, Jerahmie Radder, Russell Lagore, Brian Rutt, Qing X. Yang, Kamil Ugurbil, Riccardo Lattanzi

Research output: Contribution to journal › Article › peer-review

11 Scopus citations

Abstract

Purpose: In this work, we investigated how the position of the radiofrequency (RF) shield can affect the signal-to-noise ratio (SNR) of a receive RF coil. Our aim was to obtain physical insight for the design of a 10.5T 32-channel head coil, subject to the constraints on the diameter of the RF shield imposed by the head gradient coil geometry. Method: We used full-wave numerical simulations to investigate how the SNR of an RF receive coil depends on the diameter of the RF shield at ultra-high magnetic field (UHF) strengths (≥7T). Results: Our simulations showed that there is an SNR-optimal RF shield size at UHF strength, whereas at low field the SNR monotonically increases with the shield diameter. For a 32-channel head coil at 10.5T, an optimally sized RF shield could act as a cylindrical waveguide and increase the SNR in the brain by 27% compared to moving the shield as far as possible from the coil. Our results also showed that a separate transmit array between the RF shield and the receive array could considerably reduce SNR even if they are decoupled. Conclusion: At sufficiently high magnetic field strength, the design of local RF coils should be optimized together with the design of the RF shield to benefit from both near field and resonant modes.

Original language	English (US)
Pages (from-to)	3522-3530
Number of pages	9
Journal	Magnetic resonance in medicine
Volume	85
Issue number	6
DOIs	https://doi.org/10.1002/mrm.28670
State	Published - Jun 2021

Bibliographical note

Funding Information:
The authors thank Dr. Anke Henning and Dr. Nikolai Avdievich for useful discussions about shielding effects on receive coils. This work was supported in part by NIH U01 EB025144, NIH R01 EB024536, NIH S10 RR029672, NSF 1453675 and Cancer Prevention and Research Institute of Texas RR180056, and was performed under the rubric of the Center for Advanced Imaging Innovation and Research (CAI2R, www.cai2r.net ) and CMRR, National Centers for Biomedical Imaging and Bioengineering (NIH P41 EB017183 and P41 EB015894).

Funding Information:
National Institutes of Health, Grant/Award Numbers: U01 EB025144, R01 EB024536, R01 EB021277 and P41 EB017183; National Science Foundation (NSF), Grant/Award Number: 1453675; Cancer Prevention and Research Institute of Texas, Grant Number: RR180056 The authors thank Dr. Anke Henning and Dr. Nikolai Avdievich for useful discussions about shielding effects on receive coils. This work was supported in part by NIH U01 EB025144, NIH R01 EB024536, NIH S10 RR029672, NSF 1453675 and Cancer Prevention and Research Institute of Texas RR180056, and was performed under the rubric of the Center for Advanced Imaging Innovation and Research (CAI2R, www.cai2r.net) and CMRR, National Centers for Biomedical Imaging and Bioengineering (NIH P41 EB017183 and P41 EB015894).

Publisher Copyright:
© 2021 International Society for Magnetic Resonance in Medicine

Keywords

RF coil
RF shield
signal to noise ratio
ultra-high field MRI

Center for Magnetic Resonance Research (CMRR) tags

MRE
P41

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10.1002/mrm.28670

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title = "Effect of radiofrequency shield diameter on signal-to-noise ratio at ultra-high field MRI",

abstract = "Purpose: In this work, we investigated how the position of the radiofrequency (RF) shield can affect the signal-to-noise ratio (SNR) of a receive RF coil. Our aim was to obtain physical insight for the design of a 10.5T 32-channel head coil, subject to the constraints on the diameter of the RF shield imposed by the head gradient coil geometry. Method: We used full-wave numerical simulations to investigate how the SNR of an RF receive coil depends on the diameter of the RF shield at ultra-high magnetic field (UHF) strengths (≥7T). Results: Our simulations showed that there is an SNR-optimal RF shield size at UHF strength, whereas at low field the SNR monotonically increases with the shield diameter. For a 32-channel head coil at 10.5T, an optimally sized RF shield could act as a cylindrical waveguide and increase the SNR in the brain by 27% compared to moving the shield as far as possible from the coil. Our results also showed that a separate transmit array between the RF shield and the receive array could considerably reduce SNR even if they are decoupled. Conclusion: At sufficiently high magnetic field strength, the design of local RF coils should be optimized together with the design of the RF shield to benefit from both near field and resonant modes.",

keywords = "RF coil, RF shield, signal to noise ratio, ultra-high field MRI",

author = "Bei Zhang and Gregor Adriany and Lance Delabarre and Jerahmie Radder and Russell Lagore and Brian Rutt and Yang, {Qing X.} and Kamil Ugurbil and Riccardo Lattanzi",

note = "Funding Information: The authors thank Dr. Anke Henning and Dr. Nikolai Avdievich for useful discussions about shielding effects on receive coils. This work was supported in part by NIH U01 EB025144, NIH R01 EB024536, NIH S10 RR029672, NSF 1453675 and Cancer Prevention and Research Institute of Texas RR180056, and was performed under the rubric of the Center for Advanced Imaging Innovation and Research (CAI2R, www.cai2r.net ) and CMRR, National Centers for Biomedical Imaging and Bioengineering (NIH P41 EB017183 and P41 EB015894). Funding Information: National Institutes of Health, Grant/Award Numbers: U01 EB025144, R01 EB024536, R01 EB021277 and P41 EB017183; National Science Foundation (NSF), Grant/Award Number: 1453675; Cancer Prevention and Research Institute of Texas, Grant Number: RR180056 The authors thank Dr. Anke Henning and Dr. Nikolai Avdievich for useful discussions about shielding effects on receive coils. This work was supported in part by NIH U01 EB025144, NIH R01 EB024536, NIH S10 RR029672, NSF 1453675 and Cancer Prevention and Research Institute of Texas RR180056, and was performed under the rubric of the Center for Advanced Imaging Innovation and Research (CAI2R, www.cai2r.net) and CMRR, National Centers for Biomedical Imaging and Bioengineering (NIH P41 EB017183 and P41 EB015894). Publisher Copyright: {\textcopyright} 2021 International Society for Magnetic Resonance in Medicine",

year = "2021",

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AU - Zhang, Bei

AU - Adriany, Gregor

AU - Delabarre, Lance

AU - Radder, Jerahmie

AU - Lagore, Russell

AU - Rutt, Brian

AU - Yang, Qing X.

AU - Ugurbil, Kamil

AU - Lattanzi, Riccardo

N1 - Funding Information: The authors thank Dr. Anke Henning and Dr. Nikolai Avdievich for useful discussions about shielding effects on receive coils. This work was supported in part by NIH U01 EB025144, NIH R01 EB024536, NIH S10 RR029672, NSF 1453675 and Cancer Prevention and Research Institute of Texas RR180056, and was performed under the rubric of the Center for Advanced Imaging Innovation and Research (CAI2R, www.cai2r.net ) and CMRR, National Centers for Biomedical Imaging and Bioengineering (NIH P41 EB017183 and P41 EB015894). Funding Information: National Institutes of Health, Grant/Award Numbers: U01 EB025144, R01 EB024536, R01 EB021277 and P41 EB017183; National Science Foundation (NSF), Grant/Award Number: 1453675; Cancer Prevention and Research Institute of Texas, Grant Number: RR180056 The authors thank Dr. Anke Henning and Dr. Nikolai Avdievich for useful discussions about shielding effects on receive coils. This work was supported in part by NIH U01 EB025144, NIH R01 EB024536, NIH S10 RR029672, NSF 1453675 and Cancer Prevention and Research Institute of Texas RR180056, and was performed under the rubric of the Center for Advanced Imaging Innovation and Research (CAI2R, www.cai2r.net) and CMRR, National Centers for Biomedical Imaging and Bioengineering (NIH P41 EB017183 and P41 EB015894). Publisher Copyright: © 2021 International Society for Magnetic Resonance in Medicine

PY - 2021/6

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N2 - Purpose: In this work, we investigated how the position of the radiofrequency (RF) shield can affect the signal-to-noise ratio (SNR) of a receive RF coil. Our aim was to obtain physical insight for the design of a 10.5T 32-channel head coil, subject to the constraints on the diameter of the RF shield imposed by the head gradient coil geometry. Method: We used full-wave numerical simulations to investigate how the SNR of an RF receive coil depends on the diameter of the RF shield at ultra-high magnetic field (UHF) strengths (≥7T). Results: Our simulations showed that there is an SNR-optimal RF shield size at UHF strength, whereas at low field the SNR monotonically increases with the shield diameter. For a 32-channel head coil at 10.5T, an optimally sized RF shield could act as a cylindrical waveguide and increase the SNR in the brain by 27% compared to moving the shield as far as possible from the coil. Our results also showed that a separate transmit array between the RF shield and the receive array could considerably reduce SNR even if they are decoupled. Conclusion: At sufficiently high magnetic field strength, the design of local RF coils should be optimized together with the design of the RF shield to benefit from both near field and resonant modes.

AB - Purpose: In this work, we investigated how the position of the radiofrequency (RF) shield can affect the signal-to-noise ratio (SNR) of a receive RF coil. Our aim was to obtain physical insight for the design of a 10.5T 32-channel head coil, subject to the constraints on the diameter of the RF shield imposed by the head gradient coil geometry. Method: We used full-wave numerical simulations to investigate how the SNR of an RF receive coil depends on the diameter of the RF shield at ultra-high magnetic field (UHF) strengths (≥7T). Results: Our simulations showed that there is an SNR-optimal RF shield size at UHF strength, whereas at low field the SNR monotonically increases with the shield diameter. For a 32-channel head coil at 10.5T, an optimally sized RF shield could act as a cylindrical waveguide and increase the SNR in the brain by 27% compared to moving the shield as far as possible from the coil. Our results also showed that a separate transmit array between the RF shield and the receive array could considerably reduce SNR even if they are decoupled. Conclusion: At sufficiently high magnetic field strength, the design of local RF coils should be optimized together with the design of the RF shield to benefit from both near field and resonant modes.

KW - RF coil

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KW - signal to noise ratio

KW - ultra-high field MRI

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Effect of radiofrequency shield diameter on signal-to-noise ratio at ultra-high field MRI

Abstract

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