Measurement of Rat Magnetocardiograms by Using a High- $T_{\rm C}$ SQUID Magnetometer System

We have measured biomagnetic signals in rat by using a high-T_C SQUID magnetometer system employing a small magnetically shielded box. For the rat cardiac magnetic field measurements, a healthy rat with body weight of about 350 g was anesthetized and fixed on a plastic xyz-stage in supine position inside the magnetically shielded box. We could obtain strong R-peak amplitude up to 56 pT with well defined P-, QRS-, T-wave, and ST-segment separating T-wave from QRS complex. We measured and analysed rat MCG waveforms for 5 × 5 grid measurements covering 60 mm × 60 mm area and 12 circular measurements centered at the heart position. This work demonstrates that the potential advantages of high-T_C SQUID magnetometer system in evaluating the rat MCG measurement for animal models of cardiac electrical activities.