Magnetocardiography(MCG) has been investigated as a tool for noninvasive detection of coronary artery disease(CAD). In this study, the area ratio of positive and negative magnetic induction extracted from an extrema circle in the magnetocardiogram was analyzed at specific time points in the cardiac cycle: P maximum, R peak, J point, T onset, T peak and T end. The area of the positive proportion of the magnetic field relative to the total area within a circle encompassing the field extrema was determined and proposed for fast-speed CAD diagnosis. MCG was performed with a 61-channel biomagnetometer in a shielded environment in 38 healthy subjects and 15 CAD patients. A notable difference in area ratio was found between healthy and CAD subjects at the peak time of T wave: 0.416 ± 0.090 versus0.465 ± 0.065(p = 0.013). Using a cutoff value of 0.4506resulted in a sensitivity and specificity of 86.7 % and 73.8 %,respectively. This approach may enable a fast-speed CAD diagnosis in a clinical setting.
Tuo ChenChen ZhaoShiqin JiangPeter Van LeeuwenDietrich Grnemeyer
Cardiac current source reconstruction is investigated by a fast greedy sparse(FGS) method applied to simulated and real magnetocardiography(MCG) data measured using 61-channel superconducting quantum interference device. The approach reduces the size of the lead field matrix based on a priori knowledge of dipolar magnetic field map. Consequently, the computational demands and the accuracy of sparse source reconstruction are improved simultaneously. The simulation results demonstrate that the FGS method is capable of reconstructing sparse equivalent current sources using the magnetic field data generated by a single current source with varying orientation or multiple current sources generated randomly. In addition, we analyze the cardiac current source reconstructed with real MCG data at typical instants and discuss the electrical excitation conduction during the QRS complex based on moving sparse source imaging.
Mengpei ChenShiqin JiangLu BingChen ZhaoBirgit HailerDietrich Gr nemeyerPeter Van Leeuwen
