The barostat is considered the gold standard for evaluation of proximal gastric motility especially for the accommodation response to a meal. The procedure is invasive because it involves the introduction of an intragastric catheter and bag and is not always well tolerated. Moreover, the barostat bag itself may influence motility. Nowadays magnetic resonance imaging (MRI) is able to measure several aspects of gastric motility noninvasively. To evaluate whether the accommodation response of the stomach, observed with the barostat, is present during MRI and whether the barostat interferes with gastric physiology, gastric accommodation, motility, and emptying were studied twice in 14 healthy subjects with MRI using three-dimensional volume scans and two-dimensional dynamic scans once in the presence of a barostat bag and once when the barostat bag was not present. Fasting and postprandial intragastric volumes were significantly higher in the experiment with barostat vs. without barostat (fasting: 350 +/- 132 ml vs. 37 +/- 21 ml, P < 0.0001; postprandial: 852 +/- 126 ml vs. 361 +/- 62 ml, P < 0.0001). No significant differences were found in gastric emptying (88 +/- 41 vs. 97 +/- 40 ml/h, not significant) and contraction frequency between both experiments. The accommodation response observed in the presence of the barostat bag was not observed in the absence of the barostat bag. In conclusion, the presence of an intragastric barostat bag does not interfere with gastric emptying or motility, but the accommodation response measured with the barostat in situ is not observed without the barostat bag in situ. Gastric accommodation is a nonphysiological barostat-induced phenomenon.

Measurements of gastric volume and motility with magnetic resonance (MR) imaging were compared with simultaneously performed measurements with a barostat in six healthy volunteers. Three-dimensional volume and two-dimensional dynamic MR images and barostat measurements were obtained at rest. Alterations in gastric volume and motility were induced by means of infusion of glucagon and erythromycin, respectively. There is strong evidence to have the opinion that MR imaging is as accurate as barostat measurement in determining changes in gastric volume, and it yields additional information about gastric contractions.

Background:Evaluation of gastric physiology (gastric emptying and motility) is important for the diagnosis of disturbances such as functional dyspepsia. MRI is a non-invasive technique that allows simultaneous registration of gastric emptying and motility.Aim:To provide an overview of the literature of studies that used MRI as a tool for evaluation of gastric function in both research and clinical settings.Materials and methods:A MEDLINE search was performed (1990–2008) directed at the radiology and gastroenterology literature on gastric physiology. Key words that were used included: functional tests, gastric emptying, gastric motility, gastric physiology and MRI. Twenty-five articles fulfilled the inclusion criteria and were included in the analysis.Results and conclusion:Over the last decade, MRI has developed as a reliable, non-invasive method for detailed evaluation of gastric emptying and motility without the disadvantages of ionizing radiation and without the use of intragastric catheters that influence gastric physiology.

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Purpose: To determine the accuracy of magnetic resonance imaging (MRI) volume scans: 1) to measure known meal volumes in vitro, and 2) to compare volume changes in response to a meal measured with the barostat with those measured with MRI in vivo.Materials and Methods: Polyethylene bags were filled with known volumes and MRI volume scans were performed to determine the accuracy of the volume measurements. Barostat measurements and MRI volume scans were performed simultaneously in 14 healthy subjects before and up to 90 minutes after ingestion of a liquid meal.Results: In vitro MRI-determined volumes showed an excellent linear relationship (r ¼ 0.995, P < 0.001) with actual meal volumes. Although fasting gastric volume, postprandial gastric volume, and relaxation volume measured with MRI were significantly larger compared to volumes measured with the barostat, volumes determined with both techniques showed excellent correlation.