Use of echo planar imaging to demonstrate the effect of posture on the intragastric distribution and emptying of an oil/water meal.

Intragastric distribution of solids and liquids is far from uniform but until recently technical limitations have prevented detailed study. Echo planar imaging (EPI), which can provide high-quality images of intragastric contents, has been used in this study to assess the intragastric distribution of oil and water and gastric emptying in subjects lying on either their left or right side. Eight healthy volunteers underwent four gastric emptying studies after consuming either an aqueous meal (400 mL beef consomme soup + 100 mL water) or a fat/aqueous meal (400 mL soup + 100 mL olive oil) lying on either their left or right side. Using a water suppressed imaging mode the lipid phase was clearly seen layering above the aqueous phase with little evidence of mixing. Gastric emptying of the aqueous meal (A) was not significantly different when lying on the left compared to the right side. However, gastric emptying of the aqueous phase of the fat/aqueous meal (B) was considerably slower when lying on the left compared to the right side, gastric volumes actually increasing over the 90 min of the study P < or = 0.05. When lying on the right side the aqueous phase of meal B emptied significantly slower than meal A. Oil was clearly observed to layer above the water and fill the duodenal cap when subjects lay on their left and the fundus when they lay on their right side. EPI clearly demonstrates the intragastric layering of oil which causes posture to strongly influence gastric emptying. EPI is a tool with great potential to describe the intragastric events following ingestion of complex multiphase meals.