基于心磁信号的心脏电流偶极子阵列成像及相关性质的研究

超导量子干涉器（SQUID）能探测到微弱的心脏磁场信号. 通过对所得的心磁信号进行分析，可为许多心脏疾病的诊断提供依据. 利用心磁信号，采用极小范数最小二乘法（MNLS）对心脏的电流偶极子阵列进行重建，从而实现了对心脏内部等效电流源的成像. 在使用MNLS进行电流偶极子阵列反演重建的过程中，反演所需的心磁信号，分别由单电流偶极子和电流多极子作为激发源模拟得到，以及由SQUID实际测量得到. 同时，对不同心磁信号反演得到的电流偶极子的分布规律进行了分析. 此外，还给模拟的人体外心磁信号施加了均匀噪声和随机噪声，研究不同信噪比的均匀噪声和随机噪声对电流偶极子阵列重建的影响.

The reconstruction of cardiac current dipole array based on cardiac magnetic signals and the studies on its relative characteristics

Superconducting quantum interference device (SQUID) can detect weak cardiac magnetic signals. By analyzing those detected cardiac magnetic signals can we provide the evidence for the diagnosis of cardiac diseases. In this paper, we reconstruct the cardiac current dipole array using minimum-norm least-squares method (MNLS), thus realize the imaging of equivalent cardiac current sources. In the process of doing inverse computation using MNLS for current dipole array reconstruction, we assume that the cardiac current sources are distributed in a plane layer in human heart and the cardiac magnetic signals needed for inverse computation are obtained with three methods: the simulation based on single current dipole and current multipole models, and the realistic measurements by SQUID. Using the three methods for obtaining the cardiac magnetic signals, we discuss the distributive characteristics of current dipoles from the inverse computation. Besides, we also add the constant noise and random noise to the cardiac magnetic signals and consider their influences on the reconstruction of current dipole array.