Applied potential tomography in liquid gastric emptying measurement - Design, assembling, calibration, and clinical application

The present study aimed to validate the accuracy of a homemade applied pote ntial tomography (APT) apparatus for liquid gastric emptying (GE). Twelve e lectrodes were placed in a circular array around the subjects. Ten electrod es in a rotated order recorded electrical current delivered from a driving pair of electrodes. Based on tomography, averaged signals of changed resist ivity were constructed to display area changes. Six beakers were respective ly placed into a saline-filled Perspex tank to measure their cross-sections . True beaker cross-sections are 2.01, 15.9, 18.8, 30.19, 38.48, and 63.61 cm(2), respectively, whereas APT generated cross-sections were 7.9 +/- 2.9, 16.7 +/- 3.3, 22.4 +/- 4.9, 28 +/- 4.8, 48.7 +/- 7.6, 67 +/- 6.1 cm(2), re spectively (r = 0.98, P < 0.001). Twenty-four healthy males ingested 500-ml test solution to assess GE using both APT and scintigraphy. Only 20 (83.3% ) subjects had a successful measurement. The APT half emptying time was 15. 6 +/- 4.8 min, whereas scintigraphy was 21.9 +/- 6.3 min (r = 0.67, P < 0.0 1). In conclusion, our APT apparatus is a simple, noninvasive, and inexpens ive way to assess liquid GE. Its clinical usefulness is confirmed using bot h phantom and human models.