Measurement of GI water content using EPI at 0.5 tesla

Abstract

Recent work has shown that echo-planar magnetic resonance imaging has the potential to become a useful tool in the assessment of gastrointestinal (GI) tract motility, gastric emptying, and food rheology. This work extends this role to the measurement of water absorption in the GI tract, an important clinical measure. Currently, this involves intestinal intubation and considerable discomfort. By using multislice echo-planar magnetic resonance imaging, we can acquire a set of images covering the whole abdominal cavity in under 30 s. By suitable scaling of the pixel intensities in the small bowel and by planimetry of the areas of water in the stomach it is possible to estimate the total volume of water in the GI tract. By comparing the amount of water lost by the stomach and the amount gained by the small bowel following a test meal it is then possible to create water absorption curves. Using this method, we have shown a difference in water absorption for various solutions (water, mannitol solution, and normal saline). In addition, by assuming very slow water absorption from saline we have been able to asses the errors in this technique to be approximately 8–30%. This work, which describes the first noninvasive measure of gastrointestinal water absorption, will give important insights into clinical malabsorption states and help in the development of more effective oral rehydration therapies.