Measuring technology for cardiac magneto-field using ultra-sensitive magnetic sensor - For high speed and noninvasive cardiac examination

The electrophysical process of a human heart is noninvasively visualized and analyzed by using a multichannel quantum interference device (SQUID) system. By analyzing tangential components of the cardiac magnetic field, we can observe simultaneous activated multiple regions and intracardiac current distribution in the heart. An iso-integral mapping technique is developed as new concept projecting total current image on the torso from the heart. When we compared the iso-integral map of a normal and an ischemic heart, the ischemic heart showed different patterns for the depolarization and repolarization processes. MCG measurements of fetal hearts have become easy because of improvements in the sensitivity of sensor units and the fact that magnetic measurements are not affected by fetal fat or the mother's heart. Based on these visualization and measuring techniques, we developed a 64-channel SQUID system that can be used as an MCG for analyzing vector components of a cardiac magnetic field.