心脏磁场分布电流源重构及其精度分析

Distributed current source reconstruction of magnetocadiography and its accuracy analysis

用测量到的心脏磁场信号重构其电流源是一种无创揭示心脏电活动的方法.心脏电活动的时空信息可视化,将有助于心脏功能的研究和心脏疾病诊断.本文通过仿真实验研究了一种减时窗波束形成器对分布时变电流源的重构能力,以及源重构结果与心室兴奋传播的关系.采用元胞自动机模拟心室的兴奋传播,产生分布随时间变化的电流源,并用边界元法构建了一个心脏-躯干模型,模拟体电导的作用.仿真结果表明,这种减时窗波束形成器能够重构分布时变电流源,并达到较好的精度.将该方法和无穷大均匀介质导联矩阵用于一例正常人的心脏磁场信号分析,其结果可以反映心室兴奋传播的基本特征.

Reconstructing cardiac current source by magnetocardiogram signal is a noninvasive method of revealing cardiac electrical activity. The visualization of spatial and temporal information about cardiac electrical activity will be conducive to the analysis of the heart function and the diagnosis of heart disease. In this paper, the capability of reconstructing distribution of current sources, whose distribution is changed over time, is studied by a reduced time window （RTW） beamformer, and the relationship between source reconstruction results and ventricular excitation propagation is analyzed in simulation. The cellular automaton is used to simulate ventricular excitation propagation and to generate the current sources. Moreover, a heart-torso model is constructed by the boundary element method to simulate the effect of the volume conductor. The simulation results show that the RTW beamformer can provide a good accuracy of reconstructing the distribution of current sources. The RTW beamformer is also used to analyze a normal subject with the lead field of infinite homogeneous medium. The results demonstrate that they reflect the basic characteristic of ventricular excitation propagation.