Gastric motor function and emptying in the right decubitus and seated body position as assessed by magnetic resonance imaging

Purpose: To determine the effect of the right decubitus lying body position (RP) on relevant parameters of human gastric motor function in healthy volunteers. Materials and Methods: Postprandial gastric function after ingestion of a solid/liquid meal (150 g/150 mL) was assessed over 90 minutes in volunteers in the RP and seated position (SP). Ten healthy volunteers were imaged using two MRI systems that differed in architecture and field strength. Stomach and intragastric air volume, intragastric meal distribution, gastric emptying, and gastric peristalsis were compared between the RP and SP. Results: Body position did not affect gastric relaxation (RP, 372 ml, vs. SP, 384 mL) and initial gastric volumes (stomach: RR 458 ml, vs. SP, 462 mL: meal: RP. 377 mL vs. SP, 399 mL; intragastric air: RP, 110 mL; vs. SP, 98 mL). Postprandial stomach volume and gastric activity (RP and SP, 3.1 minute(-1)) were also similar. Meal emptying showed different characteristics, resulting in a significant but small difference in meal volume of -43 mL at t = 90 minutes (P < 0.05). Conclusion: Gastric MRI in RP is feasible for clinical research assessing gastric motor function. The subtle difference in meal emptying may be induced by posture-dependent vagal activity. This study con firms that MRI is a highly sensitive imaging technique for assessing gastrointestinal function in humans.