INSTITUTE OF PHYSICS PUBLISHING PHYSIOLOGICAL MEASUREMENT Physiol. Meas. 25 (2004) 849–861 PII: S0967-3334(04)73803-4 An anatomical model of the gastric system for producing bioelectric and biomagnetic fields M L Buist 1 , L K Cheng 1 , R Yassi 1 , L A Bradshaw 2 , W O Richards 3 and A J Pullan 1 1 Bioengineering Institute, The University of Auckland, Private Bag 92019, Auckland, New Zealand 2 Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235, USA 3 Vanderbilt University Medical Centre, Nashville, TN 37235, USA Received 18 December 2003, accepted for publication 27 April 2004 Published 22 July 2004 Online at stacks.iop.org/PM/25/849 doi:10.1088/0967-3334/25/4/006 Abstract Between 60 and 70 million people in the United States are affected by gastrointestinal disorders. Many of these conditions are difficult to assess without surgical intervention and accurate noninvasive techniques to aid in clinical assessment are needed. Through the use of a superconducting quantum interference device (SQUID) gradiometer, the weak magnetic field generated as a result of muscular activity in the digestive system can be measured. However, the interpretation of these magnetic recordings remains a significant challenge. We have created an anatomically realistic biophysically based mathematical model of the human digestive system and using this model normal gastric electrical control activity (ECA) has been simulated. The external magnetic fields associated with this gastric ECA have also been computed and are shown to be in qualitative agreement with recordings taken from normal individuals. The model framework thus provides a rational basis from which to begin interpreting magnetic recordings from normal and diseased individuals. Keywords: biodomain equations, mathematical model, digestive system, biomagnetism (Some figures in this article are in colour only in the electronic version) 1. Introduction The gastrointestinal (GI) system is essentially a long conduit connecting the mouth to the anus through which consumed food enters, is broken down and digested. The nutrients are then extracted and the waste is expelled. An intricate arrangement of nerves, smooth muscles and 0967-3334/04/040849+13$30.00 © 2004 IOP Publishing Ltd Printed in the UK 849