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SUMMARY
Gastric accommodation is a term used to describe the reduction in gastric tone and increase in compliance that follows ingestion of a meal. It involves at least two responses: "receptive relaxation" which allows the stomach to accept a volume load without a significant rise in gastric pressure and "adaptive relaxation" which modulates gastric tone in response to the specific properties of the meal ingested. Abnormal postprandial gastric accommodation occurs in several conditions and may be involved in the pathogenesis of functional dyspepsia. However, there are considerable technical difficulties in measuring the accommodation process. The current standard barostat studies, and other methods such as conventional and three dimensional ultrasound, or single photon emission computed tomography (SPECT) have significant disadvantages. The ideal technique would be non-invasive, widely available, convenient, reliable, and would not expose the subject to ionising radiation. It would also allow measurement of gastric accommodation in response to solid as well as liquid meals. There is also a need to differentiate between responses to food, gastric secretion, and air, and to simultaneously monitor changes in gastric tone, tension, motility, emptying, and transpyloric flow. New magnetic resonance imaging (MRI) techniques are being developed to address many of these needs.
INTRODUCTION
Gastric accommodation describes the reduction in gastric tone and increase in compliance that follows ingestion of a meal. These responses provide an appropriate gastric reservoir for food and enable volume to increase without a rise in gastric pressure. Cannon and Lieb were the first to observe the phenomenon of "receptive relaxation" of the stomach which occurs within seconds after gastric distension. 1 Jahnberg et al later demonstrated a second response ("adaptive relaxation") after food intake. 2 Gastric accommodation also occurs in response to duodenal distension or nutrient infusion. Thus the distribution of food within the stomach and the rate of gastric emptying vary according to which nutrients are ingested. A brain stem reflex is thought to mediate relaxation of the proximal stomach in response to a meal. Gastric tone (that is, accommodation and contraction) is therefore modulated by the central nervous system (CNS), vagal discharge, and a network of reflexes that arise from the stomach wall. 3
Abnormal gastric accommodation occurs in functional dyspepsia, 4, 5 in children with recurrent abdominal pain, 6 in...