Assessment of gastric emptying and duodenal motility upon ingestion of a liquid meal using rapid magnetic resonance imaging.

Gastric emptying is achieved by co-operation between gastric and duodenal motor activity. Therefore, evaluation of gastric emptying and its associated mechanisms would benefit clinical therapy as well as medical research. Healthy volunteers underwent rapid magnetic resonance imaging (MRI) of the abdomen along the coronal plane after ingestion of a liquid meal. The gastric fundal and duodenal areas were quantified semi-automatically by self-developed segment software. The average gastric fundal area determined by the serosal end in 40 sequential images was reduced to ∼81% 30 min after and to ∼70% 60 min after ingestion of a liquid meal. The average duodenal area also decreased to ∼86% after 30 min and to 83% after 60 min. In contrast, changes in the centre of gravity increased to about fivefold after 30 min and to about threefold after 60 min. The mean velocity of the duodenal wall mimicked changes in the centre of gravity. The application of metoclopramide, a dopamine D(2) receptor antagonist, accelerated gastric emptying, presumably due to facilitated duodenal activity even immediately after liquid meal ingestion. The ingestion of water caused fast gastric emptying in 30 min, accompanied by high duodenal motility, but it ceased after 60 min, presumably reflecting complete gastric emptying. A rapid MRI scan visualized the association between gastric emptying and duodenal motility that could be modified by calories and dopaminergic neurotransmission. Changes in the centre of gravity and mean velocity of the duodenal wall appear to quantify the motility obtained from cine MRI accurately.