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

Patrick S. Fuchs*, Rob F. Remis

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

In this article, 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 that 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 the 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 through simulations 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.

Original languageEnglish
Article number9539065
Pages (from-to)1451-1461
Number of pages11
JournalIEEE Transactions on Antennas and Propagation
Volume70
Issue number2
DOIs
Publication statusPublished - 2022

Bibliographical note

Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care
Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

Keywords

  • Born approximation
  • Dielectric parameter retrieval
  • Free induction decay (FID)
  • Magnetic resonance imaging (MRI)
  • Scattering formalism

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