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Generalized Signal Models and Direct FID-Based Dielectric Parameter Retrieval in MRI

Fuchs, Patrick S; Remis, Rob F; (2021) Generalized Signal Models and Direct FID-Based Dielectric Parameter Retrieval in MRI. IEEE Transactions on Antennas and Propagation , 70 (2) pp. 1451-1461. 10.1109/tap.2021.3111324. Green open access

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Abstract

In this paper we present full-wave signal models for magnetic and electric field measurements in magnetic resonance imaging (MRI). Our analysis is based on a scattering formalism in which the presence of an object or body is taken into account via an electric scattering source. We show that these signal models can be evaluated, provided the Green's tensors of the background field are known along with the dielectric parameters of the object and the magnetization within the excited part of the object. Furthermore, explicit signal expressions are derived in case of a small homogeneous ball that is embedded in free space and for which the quasi-static Born approximation can be applied. The conductivity and permittivity of the ball appear as explicit parameters in the resulting signal models and allow us to study the sensitivity of the measured signals with respect to these dielectric parameters. Moreover, for free induction decay signals we show that under certain conditions it is possible to retrieve the dielectric parameters of the ball from noise-contaminated induction decay signals that are based on electric or magnetic field measurements.

Type: Article
Title: Generalized Signal Models and Direct FID-Based Dielectric Parameter Retrieval in MRI
Open access status: An open access version is available from UCL Discovery
DOI: 10.1109/tap.2021.3111324
Publisher version: https://doi.org/10.1109/TAP.2021.3111324
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Born approximation, dielectric parameter retrieval, free induction decay (FID), magnetic resonance imaging (MRI), scattering formalism
UCL classification: UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Med Phys and Biomedical Eng
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL
URI: https://discovery.ucl.ac.uk/id/eprint/10142905
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