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Reconstruction of dual-frequency conductivity by optimization of phase map in MREIT and MREPT

BACKGROUND: The spectroscopic conductivity distribution of tissue can help to explain physiological and pathological status. Dual frequency conductivity imaging by combining Magnetic Resonance Electrical Property Tomography (MREPT) and Magnetic Resonance Electrical Impedance Tomography (MREIT) has b...

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Autores principales: Kwon, Oh In, Jeong, Woo Chul, K Sajib, Saurav Z, Kim, Hyung Joong, Woo, Eung Je, Oh, Tong In
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3995946/
https://www.ncbi.nlm.nih.gov/pubmed/24607262
http://dx.doi.org/10.1186/1475-925X-13-24
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author Kwon, Oh In
Jeong, Woo Chul
K Sajib, Saurav Z
Kim, Hyung Joong
Woo, Eung Je
Oh, Tong In
author_facet Kwon, Oh In
Jeong, Woo Chul
K Sajib, Saurav Z
Kim, Hyung Joong
Woo, Eung Je
Oh, Tong In
author_sort Kwon, Oh In
collection PubMed
description BACKGROUND: The spectroscopic conductivity distribution of tissue can help to explain physiological and pathological status. Dual frequency conductivity imaging by combining Magnetic Resonance Electrical Property Tomography (MREPT) and Magnetic Resonance Electrical Impedance Tomography (MREIT) has been recently proposed. MREIT can provide internal conductivity distributions at low frequency (below 1 kHz) induced by an external injecting current. While MREPT can provide conductivity at the Larmor frequency related to the strength of the magnetic field. Despite this potential to describe the membrane properties using spectral information, MREPT and MREIT techniques currently suffer from weak signals and noise amplification as they both reply on differentiation of measured phase data. METHODS: We proposed a method to optimize the measured phase signal by finding weighting factors according to the echo signal for MREPT and MREIT using the ICNE (Injected current nonlinear encoding) multi-echo pulse sequence. Our target weights are chosen to minimize the measured noise. The noise standard deviations were precisely analyzed for the optimally weighted magnetic flux density and the phase term of the positive-rotating magnetic field. To enhance the quality of dual-frequency conductivity images, we applied the denoising method based on the reaction-diffusion equation with the estimated noise standard deviations. A real experiment was performed with a hollow cylindrical object made of thin insulating film with holes to control the apparent conductivity using ion mobility and an agarose gel cylinder wrapped in an insulating film without holes to show different spectroscopic conductivities. RESULTS: The ability to image different conductivity characteristics in MREPT and MREIT from a single MR scan was shown by including the two objects with different spectroscopic conductivities. Using the six echo signals, we computed the optimized weighting factors for each echo. The qualities of conductivity images for MREPT and MREIT were improved by optimization of the phase map. The proposed method effectively reduced the random noise artifacts for both MREIT and MREPT. CONCLUSION: We enhanced the dual conductivity images using the optimally weighted magnetic flux density and the phase term of positive-rotating magnetic field based on the analysis of the noise standard deviations and applying the optimization and denoising methods.
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spelling pubmed-39959462014-05-07 Reconstruction of dual-frequency conductivity by optimization of phase map in MREIT and MREPT Kwon, Oh In Jeong, Woo Chul K Sajib, Saurav Z Kim, Hyung Joong Woo, Eung Je Oh, Tong In Biomed Eng Online Research BACKGROUND: The spectroscopic conductivity distribution of tissue can help to explain physiological and pathological status. Dual frequency conductivity imaging by combining Magnetic Resonance Electrical Property Tomography (MREPT) and Magnetic Resonance Electrical Impedance Tomography (MREIT) has been recently proposed. MREIT can provide internal conductivity distributions at low frequency (below 1 kHz) induced by an external injecting current. While MREPT can provide conductivity at the Larmor frequency related to the strength of the magnetic field. Despite this potential to describe the membrane properties using spectral information, MREPT and MREIT techniques currently suffer from weak signals and noise amplification as they both reply on differentiation of measured phase data. METHODS: We proposed a method to optimize the measured phase signal by finding weighting factors according to the echo signal for MREPT and MREIT using the ICNE (Injected current nonlinear encoding) multi-echo pulse sequence. Our target weights are chosen to minimize the measured noise. The noise standard deviations were precisely analyzed for the optimally weighted magnetic flux density and the phase term of the positive-rotating magnetic field. To enhance the quality of dual-frequency conductivity images, we applied the denoising method based on the reaction-diffusion equation with the estimated noise standard deviations. A real experiment was performed with a hollow cylindrical object made of thin insulating film with holes to control the apparent conductivity using ion mobility and an agarose gel cylinder wrapped in an insulating film without holes to show different spectroscopic conductivities. RESULTS: The ability to image different conductivity characteristics in MREPT and MREIT from a single MR scan was shown by including the two objects with different spectroscopic conductivities. Using the six echo signals, we computed the optimized weighting factors for each echo. The qualities of conductivity images for MREPT and MREIT were improved by optimization of the phase map. The proposed method effectively reduced the random noise artifacts for both MREIT and MREPT. CONCLUSION: We enhanced the dual conductivity images using the optimally weighted magnetic flux density and the phase term of positive-rotating magnetic field based on the analysis of the noise standard deviations and applying the optimization and denoising methods. BioMed Central 2014-03-08 /pmc/articles/PMC3995946/ /pubmed/24607262 http://dx.doi.org/10.1186/1475-925X-13-24 Text en Copyright © 2014 Kwon 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
Kwon, Oh In
Jeong, Woo Chul
K Sajib, Saurav Z
Kim, Hyung Joong
Woo, Eung Je
Oh, Tong In
Reconstruction of dual-frequency conductivity by optimization of phase map in MREIT and MREPT
title Reconstruction of dual-frequency conductivity by optimization of phase map in MREIT and MREPT
title_full Reconstruction of dual-frequency conductivity by optimization of phase map in MREIT and MREPT
title_fullStr Reconstruction of dual-frequency conductivity by optimization of phase map in MREIT and MREPT
title_full_unstemmed Reconstruction of dual-frequency conductivity by optimization of phase map in MREIT and MREPT
title_short Reconstruction of dual-frequency conductivity by optimization of phase map in MREIT and MREPT
title_sort reconstruction of dual-frequency conductivity by optimization of phase map in mreit and mrept
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3995946/
https://www.ncbi.nlm.nih.gov/pubmed/24607262
http://dx.doi.org/10.1186/1475-925X-13-24
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