Advanced magneto-acousto-electrical tomography based on circular arrays of omnidirectional transducers and orthogonally oriented electrodes

Magneto-acousto-electrical tomography (MAET) is a promising imaging modality capable of visualizing electrical conductivity variations in tissues. However, its imaging quality and efficiency are often compromised by the mechanical rotation and scanning processes. An advanced MAET approach that employs cyclic excitation of omnidirectional transducers and synchronous detection with orthogonally oriented electrodes is presented. The principle of MAE measurement regarding acoustic excitation and electrical detection at arbitrary positions is derived. It confirms that the signal attenuation originates from the cosine product of the angles between the conductivity boundary and the positions of the transducer and electrode. A new tomographic algorithm utilizing amplitude summation for electrode-detected signals is developed, and it is further refined through the application of square-amplitude summation for orthogonally oriented electrodes. The performance improvement is validated by accurate reconstruction of an eccentrically positioned cylindrical model, using an optimized experimental system comprising 32 sources and 4 electrodes. These promising results demonstrate that the efficiency, stability, and quality of MAET can be substantially enhanced through electrically controlled cyclic excitation and synchronous detection, thereby eliminating the need of mechanical activities. By integrating MAET with ultrasonic CT, a novel dual-modality imaging strategy that leverages both electrical and acoustic impedances can be further advanced.