The vector magnetic field of the human stomach and small bowel

The authors recorded the vector biomagnetic field associated with gastrointestinal electrical activity in nine positions around the abdomen of 10 normal human volunteers using a vector SQUID magnetometer. Gastric activity with a frequency of 3.03/spl plusmn/0.18 cpm (mean /spl plusmn/SEM) was recorded with the magnetometer in the epigastrium. Small intestinal activity was also recorded in all abdominal positions with a frequency ranging between 9.0/spl plusmn/0.43 cpm in the lower abdomen to 10.5/spl plusmn/0.28 cpm in the upper abdomen. Different components of GI activity were evident within single magnetic field recordings. These different components could be elucidated by examining different projections of the magnetic field vector These studies further demonstrate the ability of the SQUID magnetometer to detect gastrointestinal activity and also illustrate how different signal components associated with gastric and small intestinal activity may be separated.