用于心脏电活动成像的空间滤波器输出噪声抑制方法  

The method of suppressing spatial filter output noise-power gain for cardiac electrical activity imaging

作　　者：周大方[1] 张树林[2] 蒋式勤[1] Zhou Da-Fang;Zhang Shu-Lin;Jiang Shi-Qin(College of Electronics and Information Engineering,Tongji University,Shanghai 201804,China;State Key Laboratory of Functional Materials for Informatics,Shanghai Institute of Microsystem and Information Technology,Chinese Academy of Sciences,Shanghai 200050,China)

机构地区：[1]同济大学电子与信息工程学院,上海201804 [2]中国科学院上海微系统与信息技术研究所,信息功能材料国家重点实验室,上海200050

出　　处：《物理学报》2018年第15期360-368,共9页Acta Physica Sinica

基　　金：国家自然科学基金(批准号：60771030); 国家高技术研究发展计划(批准号：2008AA02Z308); 上海市科学技术发展基金(批准号：08JC1421800); 中国科学院上海微系统与信息技术研究所信息功能材料国家重点实验室开放项目(批准号：SKL2013010)资助的课题

摘　　要：利用人体表面测量的心脏磁场数据无创成像心脏电活动,需要解决的关键问题是提高其重建分布电流源偶极矩强度的分辨率.本文在最小方差波束成形(MVB)方法的基础上,提出了一种可抑制空间滤波器输出噪声功率增益(SONG)的波束成形方法,目的是通过构造一种新的滤波器权矩阵,约束空间滤波器的输出噪声功率增益,提高重建分布电流源偶极矩强度的分辨率,即分布电流源空间谱估计的源分辨能力,从而增强心脏电活动磁成像的分辨率.文中给出了电流源重建的理论分析和仿真结果;比较了该方法与MVB方法的差别;并给出了两个健康人36通道心脏磁场数据的电活动成像.结果表明,SONG方法分辨电流源的能力较强,能够观察到心脏电磁场信号R峰时刻健康人的心室电活动较强,心房电活动较弱等特征.For non-invasive imaging of cardiac electrical activity using magnetocardiogram（MCG） data measured on human body surface, a key problem that needs to be solved is to enhance the spatial resolution of reconstructing distributed current source dipole moment strength in MCG imaging. In this paper, a beamforming method of suppressing spatial filter output noise-power gain（SONG） is proposed based on the minimum variance beamforming（MVB）. The purpose is to improve the resolution of the distributed source dipole moment strength reconstruction, i.e., the ability to resolve the source for distributed current source spatial spectrum estimation, in order to enhance the resolution of the cardiac electrical activity magnetic imaging. The method offers a new spatial filter weight matrix by using a low-trace positivelysemidefinite matrix that will affect the spatial filter output power, on the premise that the influence of noise spatial spectrum of spatial filter on the estimation of current source spatial spectrum has been constrained by the noise spatial spectrum intensity normalization. The positively-semidefinite matrix is specially constructed to satisfy the condition that the eigenvalue is not greater than 1 and the trace of the matrix is lower than its order, so that it can be used to constrain the spatial filter output noise-power gain for improving the robustness to noise of the source spatial spectrum estimation.In addition, a classical model of the horizontally layered conductor is used as the heart-torso model to calculate the leadfield matrix that needs to be used in source spatial spectrum estimation. The results obtained in this study are as follows.For validating the proposed method, a theoretical analysis and simulation tests of the current source reconstruction are performed, where the SONG and MVB methods are compared and a parameter of the signal-to-noise ratio is considered according to the realistic MCG data. In this paper we also give the cardiac electrical activity imaging of 36-channel cardi

关 键 词：心脏电活动成像 心磁图 逆问题 波束成形 

分 类 号：R318[医药卫生—生物医学工程] TN713[医药卫生—基础医学]