Abstract

Magnetoacoustic tomography with magnetic induction (MAT-MI) is a noninvasive imaging modality for generating electrical conductivity images of biological tissues with high spatial resolution. In this paper, we create a numerical model, including a permanent magnet, a coil, and a two-layer coaxial cylinder with anisotropic electrical conductivities, for the MAT-MI forward problem. We analyze the MAT-MI sources in two cases, on a thin conductive boundary layer and in a homogeneous medium, and then develop a feasible numerical approach to solve the MAT-MI sound source densities in the anisotropic conductive model based on finite element analysis of electromagnetic field. Using the numerical finite element method, we then investigate the magnetoacoustic effect of anisotropic conductivity under the inhomogeneous static magnetic field and inhomogeneous magnetic field, quantitatively compute the boundary source densities in the conductive model, and calculate the sound pressure. The anisotropic conductivity contributes to the distribution of the eddy current density, Lorentz force density, and acoustic signal. The proposed models and approaches provide a more realistic simulation environment for MAT-MI.

Highlights

  • Since Henderson and Webster reported an impedance camera to generate the electrical impedance image of the thorax [1], it is of increasing interests to noninvasively measure the electrical impedance of biological tissues

  • magnetic induction tomography (MIT) excites the deep biological tissue with time-variant magnetic field and measures the secondary magnetic field produced by the eddy current to reconstruct electrical impedance images

  • In Magnetoacoustic tomography with magnetic induction (MAT-MI), an object is placed in an external static magnetic field B0 and a time-variant magnetic field B1 to induce the eddy currents J in the object

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Summary

Introduction

Since Henderson and Webster reported an impedance camera to generate the electrical impedance image of the thorax [1], it is of increasing interests to noninvasively measure the electrical impedance of biological tissues Several approaches, such as electrical impedance tomography (EIT) [2, 3], magnetic induction tomography (MIT) [4, 5], magnetic resonance EIT (MREIT) [6], magnetoacoustic tomography (MAT) [7, 8], and Hall effect imaging (HEI) [9], have been developed to image the electrical impedance distribution. MIT excites the deep biological tissue with time-variant magnetic field and measures the secondary magnetic field produced by the eddy current to reconstruct electrical impedance images. Through combining magnetism and sonography, MAT-MI can excite deep tissues and image the Computational and Mathematical Methods in Medicine et J1t en J1n dS1 et󳰀

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