Clinical application of a biomagnetic measurement system with high temperature superconduction quantum interference device

1）我们评估了是否可以通过使用高温超导量子干涉装置（高Tc-SQUID）显示电流密度来可视化心脏电流。使用32通道高Tc-SQUID（Sumitomo Electric Hightecs，Co.，（香港）在一个磁屏蔽的房间里根据磁场梯度在32个导联点获得矢量电流，并构建电流密度图。在去极化和复极化阶段清楚地检测到电流。以前，检测来自心脏的磁场需要使用液氦的昂贵SQUID系统。然而，该系统的特点是其相对较高的成本效益和良好的空间分辨率。此外，很少有研究已经完成的地图，显示心脏电流密度，这可能提供重要的信息电动势。因此，该系统可用于临床 ...更多信息 2）研究了心电图无法推断的梗死向量是否可以通过心磁图的等磁图和电流密度图检测出来。用二阶导数超导量子干涉仪（SQUID）记录陈旧性下壁心肌梗塞（MI组）15例和正常健康人（N组）20例的心电图。由相邻两点的磁场梯度计算心前区各36个记录点的电流矢量大小。对心前区电流分布进行样条插值，由电流密度图估计心脏电动势。N组所有受试者在QRS波起后30-40 msec时的QRS向量均呈顺时针方向，在体表心电图或等磁图上均不能识别出多个偶极子。此外，在N组的心室除极相的电流密度图中，推导出一个电流密度。然而，与正常人不同，MI组的心室除极相的心磁图推断出多个电流密度。也就是说，在下壁心肌患者异常Q波，QRS波开始后30-40毫秒的QRS向量在体表心电图上是向上的。非Q波下壁心肌梗死患者在等磁图上也可推断出上级QRS向量。心肌梗死组4例有多个电流源，体表心电图未检出。结果表明，心室除极向量由正常向左、向右的偶极子和下壁心肌梗塞引起的异常向上的偶极子组成。结果表明，心磁图可以检测出心电图所不能检测出的梗塞电动势。少

1)We evaluated whether the cardiac electrical current could be visualized by displaying the current density using a high temperature superconducting quantum interference device (high Tc-SQUID). Magnetic fields from heart were measured using a 32-channel high Tc-SQUID (Sumitomo Electric Hightecs, Co., Ltd.) in a magnetically shielded room. Vector currents were obtained at 32 lead points based on the magnetic gradient, and a current density map were constructed. Current electrical currents were clearly detected during depolarization and repolarization phases. Previously, the detection of magnetic field from the heart required an expensive SQUID system using liquid helium. However, this system was characterized-by its relative higher cost-effectiveness and excellent spatial resolution. In addition, few studies have been done on the map which displays cardiac current density, which can potentially provide important information on electromotive forces. Therefore, this system can be clinical … More ly applied because it facilitates the detection of detailed cardiac electrical current.2)We investigated whether an infarct vector that could not be deduced by electrocardiogram was detectable using isomagnetic and current density map of magnetocardiogram. Old inferior myocardial infarction (15 patients ; MI group) and normal healthy subjects (20 cases ; N group) were recorded with second derivative superconducting quantum interference device (SQUID) magnetocardiometer. Current vector magnitude of each 36 precordial recording point was calculated from magnetic field gradient of adjacent two points. Spline interpolation of precordial current distribution was performed and electromotive force of heart was estimated form current density map. In all subjects in the N group, the QRS vector at 30-40 msec after the onset of QRS wave was directed leftward and inferiorly and multiple dipoles could not be recognized from either surface electrocardiogram, or isomagnetic map. Moreover, in current density map of the ventricular depolarization phase in the N group, one current density was deduced. However, multiple current densities were deduced from the magnetocardiogram of the ventricular depolarization phase in the MI group unlike normal subject. That is, in inferior myocardial patient with abnormal Q wave, the QRS vector at 30-40 msec after the onset of QRS wave was directed superiorly in surface electrocardiogram. On the other hand, the superior QRS vector was deduced in isomagnetic map even in patients with non-Q wave inferior myocardial infarction. In the MI group, multiple current sources were suggested in 4 patients which did not be detected in body surface electrocardiogram. These results suggest that the ventricular depolarization vectors were composed of a normal dipole directed leftward and inferiorly, and an abnormal dipole directed superioly due to inferior myocardial infarction. It is concluded that magnetocardiogram can detect the infarct electromotive force which could not be deduced in electrocardiography. Less