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Safety for Human MR Scanners at 7T

After introduction of the first human 7 tesla (7T) system in 1999, 7T MR systems have been employed as one of the most advanced platforms for human MR research for more than 20 years. Currently, two 7T MR models are approved for clinical use in the U.S.A. The approval facilitated introduction of the...

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Autores principales: Okada, Tomohisa, Akasaka, Thai, Thuy, Dinh HD, Isa, Tadashi
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Japanese Society for Magnetic Resonance in Medicine 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9618930/
https://www.ncbi.nlm.nih.gov/pubmed/34373430
http://dx.doi.org/10.2463/mrms.rev.2021-0063
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author Okada, Tomohisa
Akasaka, Thai
Thuy, Dinh HD
Isa, Tadashi
author_facet Okada, Tomohisa
Akasaka, Thai
Thuy, Dinh HD
Isa, Tadashi
author_sort Okada, Tomohisa
collection PubMed
description After introduction of the first human 7 tesla (7T) system in 1999, 7T MR systems have been employed as one of the most advanced platforms for human MR research for more than 20 years. Currently, two 7T MR models are approved for clinical use in the U.S.A. The approval facilitated introduction of the 7T system, summing up to around 100 worldwide. The approval in Japan is much awaited. As a clinical MR scanner, the 7T MR system is drawing attention in terms of safety. Several large-sized studies on bioeffects have been reported for vertigo, dizziness, motion disturbances, nausea, and others. Such effects might also be found in MR workers and researchers. Frequency and severity of reported bioeffects will be presented and discussed, including their variances. The high resonance frequency and shorter RF wavelength of 7T increase the concern about the safety. Homogeneous RF pulse excitation is difficult even for the brain, and a multi-channel parallel transmit (pTx) system is considered mandatory. However, pTx may create a hot spot, which makes the estimation of specific absorption rate (SAR) to be difficult. The stronger magnetic field of 7T causes a large force of displacement and heating on metallic implants or devices, and the scan of patients with them should not be conducted at 7T. However, there are some opinions that such patients might be scanned even at 7T, if certain criteria are met. This article provides a brief review on the effect of the static magnetic field on humans (MR subjects, workers, and researchers) and neurons, in addition to scan sound, SAR, and metal implants and devices. Understanding and avoiding adverse effects will contribute to the reduction in safety risks and the prevention of incidents.
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spelling pubmed-96189302022-11-14 Safety for Human MR Scanners at 7T Okada, Tomohisa Akasaka, Thai Thuy, Dinh HD Isa, Tadashi Magn Reson Med Sci Review After introduction of the first human 7 tesla (7T) system in 1999, 7T MR systems have been employed as one of the most advanced platforms for human MR research for more than 20 years. Currently, two 7T MR models are approved for clinical use in the U.S.A. The approval facilitated introduction of the 7T system, summing up to around 100 worldwide. The approval in Japan is much awaited. As a clinical MR scanner, the 7T MR system is drawing attention in terms of safety. Several large-sized studies on bioeffects have been reported for vertigo, dizziness, motion disturbances, nausea, and others. Such effects might also be found in MR workers and researchers. Frequency and severity of reported bioeffects will be presented and discussed, including their variances. The high resonance frequency and shorter RF wavelength of 7T increase the concern about the safety. Homogeneous RF pulse excitation is difficult even for the brain, and a multi-channel parallel transmit (pTx) system is considered mandatory. However, pTx may create a hot spot, which makes the estimation of specific absorption rate (SAR) to be difficult. The stronger magnetic field of 7T causes a large force of displacement and heating on metallic implants or devices, and the scan of patients with them should not be conducted at 7T. However, there are some opinions that such patients might be scanned even at 7T, if certain criteria are met. This article provides a brief review on the effect of the static magnetic field on humans (MR subjects, workers, and researchers) and neurons, in addition to scan sound, SAR, and metal implants and devices. Understanding and avoiding adverse effects will contribute to the reduction in safety risks and the prevention of incidents. Japanese Society for Magnetic Resonance in Medicine 2021-08-06 /pmc/articles/PMC9618930/ /pubmed/34373430 http://dx.doi.org/10.2463/mrms.rev.2021-0063 Text en ©2021 Japanese Society for Magnetic Resonance in Medicine https://creativecommons.org/licenses/by-nc-nd/4.0/This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/4.0/ (https://creativecommons.org/licenses/by-nc-nd/4.0/)
spellingShingle Review
Okada, Tomohisa
Akasaka, Thai
Thuy, Dinh HD
Isa, Tadashi
Safety for Human MR Scanners at 7T
title Safety for Human MR Scanners at 7T
title_full Safety for Human MR Scanners at 7T
title_fullStr Safety for Human MR Scanners at 7T
title_full_unstemmed Safety for Human MR Scanners at 7T
title_short Safety for Human MR Scanners at 7T
title_sort safety for human mr scanners at 7t
topic Review
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9618930/
https://www.ncbi.nlm.nih.gov/pubmed/34373430
http://dx.doi.org/10.2463/mrms.rev.2021-0063
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