Transducer influence on magnetoacoustic tomography with magnetic induction based on 3D equivalent source analysis for tissues

Abstract

As a noninvasive imaging modality based on the coupling of magnetic and acoustic fields, magnetoacoustic tomography with magnetic induction (MAT-MI) has been demonstrated to have the capability of imaging the variation of conductivity distribution inside the object. However, the image resolution is still limited by the parameters of the receiver. Based on the theory of acoustic dipole, 3D equivalent source analysis was used to simulate transducer detected pressures and waveforms for MAT-MI. The influence of transducer was studied both theoretically and experimentally for a cylindrical model. It is demonstrated that large-radius transducer with strong reception pattern can detect the acoustic signals transmitted along its normal direction with sharp pressure peaks, reflecting the divergence of the induced Lorentz force. By considering the effect of acoustic attenuation and the accuracy of image reconstruction, the acoustic pressure with acceptable peak pressure ratio and improved SNR can be detected when the scanning distance is 5-10 times the radius of the object. Wide bandwidth transducer should also be selected to reduce the boundary width of borderline stripes and improve the spatial resolution of reconstructed images. The favorable results confirm the influence of transducer on MAT-MI and also provide the fundamentals for transducer selection in further study to improve the accuracy of electrical impedance reconstruction.