CORRELATION AND COMPARISON OF MAGNETIC AND ELECTRIC DETECTION OF SMALL-INTESTINAL ELECTRICAL-ACTIVITY

The small intestinal basic electrical rhythm (BER) was detected simult aneously with serosal electrodes and a transabdominal superconducting quantum interference device (SQUID) magnetometer in anesthetized rabbi ts. We induced mesenteric ischemia to correlate serosal electrode reco rding of changes in BER with the SQUID magnetometer. The BER frequency was obtained by spectral analysis of the data using Fourier and autor egressive techniques. There was a high degree of correlation (r = 0.96 ) between the BER frequency determined using the serosal electrodes an d the BER frequency ascertained from SQUID data. Additionally, the eff ects of an electrical insulator on the external electric and magnetic fields were studied in the rabbit model. The presence of an insulator profoundly attenuates external electric potentials recorded by cutaneo us electrodes but does not significantly affect external magnetic fiel ds or serosal potentials. We conclude that SQUID magnetometers could n oninvasively record small intestinal BER that was highly correlated wi th the activity recorded by invasive serosal electrodes. The advantage s of magnetic field measurements have encouraged us to investigate cli nical applications.