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Correlation analysis between the complex electrical permittivity and relaxation time of tissue mimicking phantoms in 7 T MRI

Dielectric relaxation theory describes the complex permittivity of a material in an alternating field; in particular, Debye theory relates the time it takes for an applied field to achieve the maximum polarization and the electrical properties of the material. Although, Debye’s equations were propos...

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Autores principales: Hernandez, Daniel, Kim, Kyoung-Nam
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9474530/
https://www.ncbi.nlm.nih.gov/pubmed/36104392
http://dx.doi.org/10.1038/s41598-022-19832-y
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author Hernandez, Daniel
Kim, Kyoung-Nam
author_facet Hernandez, Daniel
Kim, Kyoung-Nam
author_sort Hernandez, Daniel
collection PubMed
description Dielectric relaxation theory describes the complex permittivity of a material in an alternating field; in particular, Debye theory relates the time it takes for an applied field to achieve the maximum polarization and the electrical properties of the material. Although, Debye’s equations were proposed for electrical polarization, in this study, we investigate the correlation between the magnetic longitudinal relaxation time T1 and the complex electrical permittivity of tissue-mimicking phantoms using a 7 T magnetic resonance scanner. We created phantoms that mimicked several human tissues with specific electrical properties. The electrical properties of the phantoms were measured using bench-test equipment. T1 values were acquired from phantoms using MRI. The measured values were fitted with functions based on dielectric estimations, using relaxation times of electrical polarization, and the mixture theory for dielectrics. The results show that, T1 and the real permittivity are correlated; therefore, the correlation can be approximated with a rational function in the case of water-based phantoms. The correlation between index loss and T1 was determined using a fitting function based on the Debye equation and mixture theory equation, in which the fraction of the materials was taken into account. This phantom study and analysis provide an insight into the application relaxation times used for estimating dielectric properties. Currently, the measurement of electrical properties based on dielectric relaxation theory is based on an antenna, sometimes invasive, that irradiates an electric field into a small sample; thus, it is not possible to create a map of electrical properties for a complex structure such as the human body. This study could be further used to compute the electrical properties maps of tissues by scanning images and measuring T1 maps.
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spelling pubmed-94745302022-09-16 Correlation analysis between the complex electrical permittivity and relaxation time of tissue mimicking phantoms in 7 T MRI Hernandez, Daniel Kim, Kyoung-Nam Sci Rep Article Dielectric relaxation theory describes the complex permittivity of a material in an alternating field; in particular, Debye theory relates the time it takes for an applied field to achieve the maximum polarization and the electrical properties of the material. Although, Debye’s equations were proposed for electrical polarization, in this study, we investigate the correlation between the magnetic longitudinal relaxation time T1 and the complex electrical permittivity of tissue-mimicking phantoms using a 7 T magnetic resonance scanner. We created phantoms that mimicked several human tissues with specific electrical properties. The electrical properties of the phantoms were measured using bench-test equipment. T1 values were acquired from phantoms using MRI. The measured values were fitted with functions based on dielectric estimations, using relaxation times of electrical polarization, and the mixture theory for dielectrics. The results show that, T1 and the real permittivity are correlated; therefore, the correlation can be approximated with a rational function in the case of water-based phantoms. The correlation between index loss and T1 was determined using a fitting function based on the Debye equation and mixture theory equation, in which the fraction of the materials was taken into account. This phantom study and analysis provide an insight into the application relaxation times used for estimating dielectric properties. Currently, the measurement of electrical properties based on dielectric relaxation theory is based on an antenna, sometimes invasive, that irradiates an electric field into a small sample; thus, it is not possible to create a map of electrical properties for a complex structure such as the human body. This study could be further used to compute the electrical properties maps of tissues by scanning images and measuring T1 maps. Nature Publishing Group UK 2022-09-14 /pmc/articles/PMC9474530/ /pubmed/36104392 http://dx.doi.org/10.1038/s41598-022-19832-y Text en © The Author(s) 2022 https://creativecommons.org/licenses/by/4.0/Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) .
spellingShingle Article
Hernandez, Daniel
Kim, Kyoung-Nam
Correlation analysis between the complex electrical permittivity and relaxation time of tissue mimicking phantoms in 7 T MRI
title Correlation analysis between the complex electrical permittivity and relaxation time of tissue mimicking phantoms in 7 T MRI
title_full Correlation analysis between the complex electrical permittivity and relaxation time of tissue mimicking phantoms in 7 T MRI
title_fullStr Correlation analysis between the complex electrical permittivity and relaxation time of tissue mimicking phantoms in 7 T MRI
title_full_unstemmed Correlation analysis between the complex electrical permittivity and relaxation time of tissue mimicking phantoms in 7 T MRI
title_short Correlation analysis between the complex electrical permittivity and relaxation time of tissue mimicking phantoms in 7 T MRI
title_sort correlation analysis between the complex electrical permittivity and relaxation time of tissue mimicking phantoms in 7 t mri
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9474530/
https://www.ncbi.nlm.nih.gov/pubmed/36104392
http://dx.doi.org/10.1038/s41598-022-19832-y
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