注入电流式磁声成像平面模型的逆问题研究

注入电流式磁声成像是电阻抗成像和超声成像相结合的一种新型成像技术,具有电阻抗成像的高对比度和超声成像高分辨率的优势,是一种有望获得高质量图像的生物电阻抗成像技术,在生物医学成像领域具有广阔的应用前景。作为一种新型成像技术,目前在电导率的重建方面还没有形成完整的体系。针对二维平面模型,提出一种由声场信号准确重建被测样品电流密度的方法。首先采用维纳滤波反卷积方法由超声换能器测量的声场信号重建被测样品原始声场p(r,t),接着利用时间反演法获取声源分布0??(J×B),然后考虑到二维平面模型只有电流密度的两个分量,结合电流连续性定理,从而重建电流密度的两个分量xJ、yJ,最后设计并搭建注入式磁声成像实验平台,利用生物组织进行实验,最终得到猪肉组织的电导率图像,重建结果证明了重建方法的可行性。

The Inverse Problem Study of Plane Model Based on Magneto-Acoustic Tomography with Current Injection

Magneto-acoustic tomography with current injection (MAT-CI) is a new imaging technology combined with electrical impedance tomography and ultrasound imaging. It has the advantages of high contrast in electrical impedance tomography and high spatial resolution in ultrasound imaging. MAT-CI will have a broad application prospect in the field of bio-impedance imaging which is expected to obtain high quality images. In this paper, a new method for reconstructing the current density of the sample by the ultrasonic field signal is proposed. Firstly, using Wiener filtering deconvolution method, the original sound fieldp(r,t) is reconstructed by acoustic signals measured by the ultrasonic transducers. And then the sound source distribution(0)??(J×B) is obtained by the time inversion method. Secondly, taken into account the only two components of the current density in the two-dimensional plane model, according to the current continuity theorem, the two components of the current density are reconstructed. Finally, the experimental platform with hardware system was established for MAT-CI. Using the biological tissue as the sample, the experiments were carried out. The conductivity image of the pork tissue was acquired. The reconstructed image showsthat this method is feasible.