Abstract:
Overlapping symptoms of digestive diseases often require protracted visits and tests, resulting chronic degradation in quality of life and increasing socioeconomic burden. Clinical electrogastrogram (EGG) offers a non-invasive way of directly assessing patients presenting with abnormal gastric electrical activity symptoms. Clinical EGG remains largely experimental due to insufficient characterisation between gastric electrical activity, or slow waves and cutaneous EGG recordings. This thesis presents three methodologies which were used to redefine the current methodology and also further develop the clinical applications of EGG. The first method employed mathematical modelling to simulate EGG from a torso model with a fixed equivalent dipole representing gastric slow waves, solved using the boundary element method. The results gave insight into spectral and spatial relationships as well as investigating potential EGG lead analysis techniques. The spectral results showed direct correlation of frequency between EGG and gastric slow waves. Spatial results indicated a 110 mm radius range within which the EGG signals were above the half-power threshold, indicating a potential working range for the future. EGG lead analysis highlighted one potential lead configuration that closely resembled the dipole profile. The second methodology included the development of a torso tank setup, which allowed for experimental protocols to investigate how gastric slow waves correlate to EGG without interferences from other organs and biological variances. The dipole used in the simulated results was generated within the torso tank and compared to the simulated results. An average of 5.85% difference was found between the simulation and recorded results, validating the simulation and experimental methodology. Finally, a meta-analysis was implemented with the aim to refine the EGG reference range of 2.0-4.0 cycles per minute (cpm) to increase the clinical diagnostic capabilities of the current EGG methodology. The results showed that the normal EGG reference range can be refined to 2.9-3.0 cpm, which has the potential to greatly increase the diagnostic capabilities of the EGG. With validation of these findings in EGG recordings from human subjects, we expect a significant improvement to the current clinical practice of EGG.