The human vector magnetogastrogram and magnetoenterogram

Electrical activity in the gastrointestinal system produces magnetic fields that may be measured with superconducting quantum interference device magn etometers, Although typical magnetometers have detection coils that measure a single component of the magnetic field, gastric and intestinal magnetic fields are vector quantities. We recorded gastric and intestinal magnetic f ields from nine abdominal sections in nine normal human volunteers using a vector magnetometer that measures all three Cartesian components of the mag netic field vector. A vector projection technique was utilized to separate the magnetic field vectors corresponding to gastric and intestinal activity , The gastric magnetic field vector was oriented in a cephalad direction, c onsistent with previously observed data, and displayed oscillatory characte ristics of gastric electrical activity (f = 3.03 +/-0.18 cycles/min), Altho ugh the small bowel magnetic field vector showed no consistent orientation, the characteristic frequency gradient of the small bowel electrical activi ty was observed. Gastric and intestinal magnetic field vectors were oriente d in different directions and were thus distinguished by the vector project ion technique. The observed difference in direction of gastric and intestin al magnetic field vectors indicates that vector recordings dramatically inc rease the ability to separate physiological signal components from nonphysi ological components and to distinguish between different physiological comp onents.