Boundary normal pressure-based electrical conductivity reconstruction for magneto-acoustic tomography with magnetic induction

Abstract

As a kind of multi-physics imaging approach integrating the advantages of electrical impedance tomography and ultrasound imaging with the improved spatial resolution and image contrast, magneto-acoustic tomography with magnetic induction (MAT-MI) is demonstrated to have the capability of electrical impedance contrast imaging for biological tissues with conductivity differences. By being detected with a strong directional transducer, abrupt pressure change is proved to be generated by the gradient of the induced Lorentz force along the force direction at conductivity boundary. A simplified boundary normal pressure (BNP)-based conductivity reconstruction algorithm is proposed and the formula for conductivity distribution inside the object with the clear physical meaning of pressure derivative, is derived. Numerical simulations of acoustic pressure and conductivity reconstruction are conducted based on a 2-layer eccentric cylindrical phantom model using Hilbert transform. The reconstructed two-dimensional conductivity images accord well with the model, thus successfully making up the deficiency of only imaging conductivity boundary in traditional MAT-MI. The proposed method is also demonstrated to have a spatial resolution of one wavelength. This study provides a new method of reconstructing accurate electrical conductivity and suggests the potential applications of MAT-MI in imaging biological tissues with conductivity difference.

A Review on the Coupled Method of Using the Magnetic and Acoustic Fields for Biological Tissue Imaging

“…For cylindrical models with abrupt changes in the conductivity boundary, the signal generated at the boundary was demonstrated to be determined by the components of the anisotropic conductivity tensor along the x and y directions. The relationship between the conductivity boundary and internal imaging were proposed by Guo et al [12] On account of a two-layer eccentric cylindrical model, the acoustic pressure, the conductivity reconstruction method was numerically simulated using the Hilbert transform. The reconstruction results obtained by using this method demonstrate that it fits better with the model, and successfully converts the conductivity boundary.…”

New Method for 3D Transient Eddy Current Field Calculation and Its Application in Magneto-Acoustic Tomography *

“…The reconstruction of conductivity from acoustic pressure takes two steps. In the first step, ∇ • (𝐽 × 𝐵 0 ) is reconstructed from acoustic pressure by the method of time reversal, [31] ∇…”

Detailed Analytical Approach to Solve the Magnetoacoustic Tomography with Magnetic Induction (MAT-MI) Problem for Three-Layer Objects

“…However, the occurrence of this physics phenomena still require careful scientific study in a quantitative way [11][12][13]. In particular, analytical and numerical calculations can provide new and important information about the nature of the electromagnetic-acoustic phenomenon [14][15][16][17][18][19]. The literature on the subject is extensive and the cited references should only be treated as representative examples.…”

“…This problem has never been fully considered in the past, as in this article. Although similar problems were analyzed, either the authors did not quantify the details of eddy currents and Lorentz forces, or the objects' shapes or number of layers were different [6,8,9,[11][12][13][14][15][16][17][18][19]21,22,25].…”