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In magnetoacoustic tomography with magnetic induction and magnetically mediated thermoacoustic imaging, tissues are exposed to an alternating field, generating magnetoacoustic and thermoacoustic effects in the tissues. This study aimed to investigate the relationship between magnetoacoustic and thermoacoustic effects in a low-conductivity object put in a Gauss-pulsed alternating magnetic field. First, the derivations of the magnetic flux density and electric field strength induced by a Gauss-pulsed current flowing through the coil based on the theory of electromagnetic field were examined. Second, the analytical solution of the magnetic field was studied by simulation. To validate the accuracy of the analytical solution, the analytical solution and the numerical simulation of the magnetic flux density were compared. It shows that the analytical solution coincides with the numerical simulation well. Then, based on the theoretical analysis of the acoustic source generation, numerical studies were conducted to simulate pressures excited by magnetoacoustic and thermoacoustic effects in low-conductivity objects similar to tissues in the Gauss-pulsed magnetic field. The thermoacoustic effect played a leading role in low-conductivity objects placed in the Gauss-pulsed magnetic field, and the magnetoacoustic effect could be ignored. This study provided the theoretical basis for further research on magnetoacoustic tomography with magnetic induction and magnetically mediated thermoacoustic imaging for pathological tissues.

Magnetically Mediated Thermoacoustic Imaging (MMTAI) is a new imaging technology that uses the thermoacoustic effect of electromagnetic fields. It is capable of a high resolution in ultrasonic imaging and high contrast in electrical impedance imaging. It has considerable potential applications in the early diagnosis of diseases. First, this paper describes the theoretical analysis and numerical simulation of MMTAI. For B-scan thermoacoustic imaging, the thermoacoustic image of a two-dimensional model is simulated and analyzed. The numerical simulation results provide theoretical guidance for the design of the experiment. Second, the B-scan experimental system of MMTAI is designed and built. The imaging experiment was carried out using an imitation gel that contains sodium chloride as the target, and the imaging results were basically consistent with the conductivity distribution of the target. Numerical simulation and physical experiments verify the feasibility of the MMTAI method for low conductivity media. This preliminary study has shown the feasibility of the technique to detect conductivity boundaries, making it relevant for the future application of this method in the field of biomedical imaging.