Unshielded fetal magnetocardiography system using two-dimensional gradiometers.

The Review of scientific instruments

PubMedID: 18377051

Seki Y, Kandori A, Kumagai Y, Ohnuma M, Ishiyama A, Ishii T, Nakamura Y, Horigome H, Chiba T. Unshielded fetal magnetocardiography system using two-dimensional gradiometers. Rev Sci Instrum. 2008;79(3):036106.
We developed a fetal magnetocardiography (fMCG) system that uses a pair of two-dimensional gradiometers to achieve high signal-to-noise ratio. The gradiometer, which is based on a low-Tc superconducting quantum interference device, detects the gradient of a magnetic field in two orthogonal directions. Gradiometer position is easy to adjust by operating the gantry to drive the cryostat in both the swinging and axial directions. As a result, a fMCG waveform for 25 weeks' gestation was measured under an unshielded environment in real time. Moreover, the P and T waves for 25 and 34 weeks' gestation, respectively, were obtained by averaging. These results indicate that this two-dimensional gradiometer is one of the most promising techniques for measuring fetal heart rate and diagnosing fetal arrhythmia.