注入电流式磁声成像的电导率模型构建和实验研究

Study on Imaging with Current Exciting Conductivity Model Based on Magnetoacoustic Effect

基于磁声耦合效应的电导率成像是一种新型的生物组织功能成像技术,本课题旨在对注入电流式磁声成像方法进行仿真和实验研究。以金属圆环作为成像目标,将其置于稳恒磁场中,并对其加载微秒级正弦脉冲激励,对磁声耦合作用下产生的声振动进行检测和分析。借助有限元方法对磁声正问题进行仿真,同时建立注入电流式磁声耦合成像实验装置,对电导率模型产生的声信号进行检测,并利用所检测到的声信号直接重建模型的电导率边界图像。仿真结果表明,声源的平面分布能够体现成像目标电导率的边界。实验结果与仿真结果具有较好的一致性,重建图像分辨率达到cm量级。所进行的研究证明,注入式磁声耦合成像可反映被成像模型的电导率分布特征,为该方法用于复杂电导率分布组织的研究奠定了基础。

Magnetoacoustic imaging with electrical exciting is a newly proposed imaging approach to conduct noninvasive electrical conductivity imaging of biological tissue. In this paper, the imaging method is studied using computer simulation and experiment. Objects of metal coils was placed in a static magnetic field. Microsecond sine pulse stimulations were imposed on the objects and the acoustic responses generated by magnetoacoustic effect were detected and analyzed. The finite element method was applied in magnetoacoustic forward simulation, while an experimental device was established to measure the acoustic signal from the conductivity models. The conductivity boundary image was reconstructed from the measured data. Simulation results showed that the distribution of the acoustic source could reflect the sharp change of conductivity produced by the boundary of the objects. Results of the simulation and experiment were in a good agreement, and the resolution of the reconstructed images was less than 1 cm. Our investigation proves the feasibility of the electrical exciting magnetoacoustic imaging method to reflect the conductivity information, providing a foundation of further study on tissues with complex conductivity distribution.