Biomagnetic 3-dimensional spatial and temporal characterization of electrical activity of human stomach

Biomagnetic measurements are based on the noninvasive recording of magnetic signals produced by biological sources such as nervous system and muscle. The aim of this study was to obtain multichannel magnetic field recordings from the human gastrointestinal tract and to localize the sources of these signals three-dimensionally. The magnetic field was recorded in eight human healthy subjects using a sensor array with 37 superconducting quantum interference devices (SQUIDs); an electrogastrogram was recorded simultanously. Biomagnetic source localization was carried out with an iterative nonlinear optimization algorithm using the model of an equivalent current dipole (ECD) and correlated to magnetic resonance imaging (MRI) in four volunteers. Magnetogastrograms and electrogastrograms demonstrated a similar frequency distribution with a peak at 3/min. In all subjects the centers of the calculated dipoles plotted vs time showed a characteristic migration across the stomach area. One volunteer demonstrated tachygastric episodes, during which his magnetic field amplitudes increased fivefold and his dipole migration disappeared. In absence of an attack his recordings changed to normal. This demonstrates multichannel magnetic recordings can be used to localize the sources of the biomagnetic field, which could be useful for the understanding of motility disturbances.