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Microwave open-ended coaxial dielectric probe: interpretation of the sensing volume re-visited

BACKGROUND: Tissue dielectric properties are specific to physiological changes and consequently have been pursued as imaging biomarkers of cancer and other pathological disorders. However, a recent study (Phys Med Biol 52:2637–2656, 2007; Phys Med Biol 52:6093–6115, 2007), which utilized open-ended...

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Autores principales: Meaney, Paul M, Gregory, Andrew P, Epstein, Neil R, Paulsen, Keith D
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4083041/
https://www.ncbi.nlm.nih.gov/pubmed/25002909
http://dx.doi.org/10.1186/1756-6649-14-3
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author Meaney, Paul M
Gregory, Andrew P
Epstein, Neil R
Paulsen, Keith D
author_facet Meaney, Paul M
Gregory, Andrew P
Epstein, Neil R
Paulsen, Keith D
author_sort Meaney, Paul M
collection PubMed
description BACKGROUND: Tissue dielectric properties are specific to physiological changes and consequently have been pursued as imaging biomarkers of cancer and other pathological disorders. However, a recent study (Phys Med Biol 52:2637–2656, 2007; Phys Med Biol 52:6093–6115, 2007), which utilized open-ended dielectric probing techniques and a previously established sensing volume, reported that the dielectric property contrast may only be 10% or less between breast cancer and normal fibroglandular tissue whereas earlier data suggested ratios of 4:1 and higher may exist. Questions about the sensing volume of this probe relative to the amount of tissue interrogated raise the distinct possibility that the conclusions drawn from that study may have been over interpreted. METHODS: We performed open-ended dielectric probe measurements in two-layer compositions consisting of a background liquid and a planar piece of Teflon that was translated to predetermined distances away from the probe tip to assess the degree to which the probe produced property estimates representative of the compositional averages of the dielectric properties of the two materials resident within a small sensing volume around the tip of the probe. RESULTS: When Teflon was in contact with the probe, the measured properties were essentially those of pure Teflon whereas the properties were nearly identical to those of the intervening liquid when the Teflon was located more than 2 mm from the probe tip. However, when the Teflon was moved closer to the probe tip, the dielectric property measurements were not linearly related to the compositional fraction of the two materials, but reflected nearly 50% of those of the intervening liquid at separation distances as small as 0.2 mm, and approximately 90% of the liquid when the Teflon was located 0.5 mm from the probe tip. CONCLUSION: These results suggest that the measurement methods reported in the most recent breast tissue dielectric property study are not likely to return the compositional averages of the breast tissue specimens evaluated, and thus, the conclusions reached about the expected dielectric property contrast in breast cancer from this specimen study may not be correct.
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spelling pubmed-40830412014-07-08 Microwave open-ended coaxial dielectric probe: interpretation of the sensing volume re-visited Meaney, Paul M Gregory, Andrew P Epstein, Neil R Paulsen, Keith D BMC Med Phys Research Article BACKGROUND: Tissue dielectric properties are specific to physiological changes and consequently have been pursued as imaging biomarkers of cancer and other pathological disorders. However, a recent study (Phys Med Biol 52:2637–2656, 2007; Phys Med Biol 52:6093–6115, 2007), which utilized open-ended dielectric probing techniques and a previously established sensing volume, reported that the dielectric property contrast may only be 10% or less between breast cancer and normal fibroglandular tissue whereas earlier data suggested ratios of 4:1 and higher may exist. Questions about the sensing volume of this probe relative to the amount of tissue interrogated raise the distinct possibility that the conclusions drawn from that study may have been over interpreted. METHODS: We performed open-ended dielectric probe measurements in two-layer compositions consisting of a background liquid and a planar piece of Teflon that was translated to predetermined distances away from the probe tip to assess the degree to which the probe produced property estimates representative of the compositional averages of the dielectric properties of the two materials resident within a small sensing volume around the tip of the probe. RESULTS: When Teflon was in contact with the probe, the measured properties were essentially those of pure Teflon whereas the properties were nearly identical to those of the intervening liquid when the Teflon was located more than 2 mm from the probe tip. However, when the Teflon was moved closer to the probe tip, the dielectric property measurements were not linearly related to the compositional fraction of the two materials, but reflected nearly 50% of those of the intervening liquid at separation distances as small as 0.2 mm, and approximately 90% of the liquid when the Teflon was located 0.5 mm from the probe tip. CONCLUSION: These results suggest that the measurement methods reported in the most recent breast tissue dielectric property study are not likely to return the compositional averages of the breast tissue specimens evaluated, and thus, the conclusions reached about the expected dielectric property contrast in breast cancer from this specimen study may not be correct. BioMed Central 2014-06-17 /pmc/articles/PMC4083041/ /pubmed/25002909 http://dx.doi.org/10.1186/1756-6649-14-3 Text en Copyright © 2014 Meaney et al.; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research Article
Meaney, Paul M
Gregory, Andrew P
Epstein, Neil R
Paulsen, Keith D
Microwave open-ended coaxial dielectric probe: interpretation of the sensing volume re-visited
title Microwave open-ended coaxial dielectric probe: interpretation of the sensing volume re-visited
title_full Microwave open-ended coaxial dielectric probe: interpretation of the sensing volume re-visited
title_fullStr Microwave open-ended coaxial dielectric probe: interpretation of the sensing volume re-visited
title_full_unstemmed Microwave open-ended coaxial dielectric probe: interpretation of the sensing volume re-visited
title_short Microwave open-ended coaxial dielectric probe: interpretation of the sensing volume re-visited
title_sort microwave open-ended coaxial dielectric probe: interpretation of the sensing volume re-visited
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4083041/
https://www.ncbi.nlm.nih.gov/pubmed/25002909
http://dx.doi.org/10.1186/1756-6649-14-3
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