Principle and Performance of Magnetically Induced Magnetoacoustic Tomography for Tissues with Cone Shaped Transducer

Abstract

The theory on the principle of the Magnetically Induced Magnetoacoustic Tomography (MI-MAT) with a cone shaped transducer in cylindrical measure configuration is proposed in this paper. The principle of MI-MAT generation and magnetoacoustic detection are theoretically deduced in formula. It is proved that the acoustic waveforms are mainly generated at the conductivity boundaries and only the configuration of the scanned layer can be reconstructed without the inner conductivity distribution using the waveforms detected around the object with the cone shaped transducer. The performance of MI-MAT, including the improved resolution at high frequency excitation and the favorable SNR dependence, provides a noninvasive means for conductivity differentiation in diagnostic imaging. The numerical simulations of the proposed theory for a cylindrical sample phantom have good agreements with the former published results and suggest the potential applications for bioimpedance imaging.

Reception pattern influence on magnetoacoustic tomography with magnetic induction

“…In most previous studies [1][2][3][4]6,7,9,11,13,15,16] of MAT-MI experiments, planar piston transducers with a radius of about 1-3 cm were used as the receiver to detect the acoustic pressure. Although the conductivity boundary of the scanned layer can be presented in the reconstructed images, the broad borderline stripes are observed with reduced image resolution and contrast, and the conductivity changes cannot be reflected accurately by the amplitudes of the boundary stripes due to the influence of the transducer reception pattern.…”

“…For acoustic detection, the pressure is closely related with the reception pattern of the transducer. Figure 4(a) describes the ideal reception pattern of a unidirectional transducer, [15] indicating that only the pressure transmitted along the normal direction of the transducer can be detected. So for the 2D measurement configuration in Fig.…”

“…In MAT-MI, a transducer with an ideal reception pattern [15] can only detect acoustic signals transmitted along the normal direction of the transducer surface. The information of the acoustic source strength, vibration polarity, and the location of conductivity boundaries can be easily extracted from the collected signals, which is beneficial for the conductivity reconstruction of the scanned layer.…”