Gastric volume changes in response to a meal: validation of magnetic resonance imaging versus the barostat

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 = 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.

Conclusion:

Volumes in the range of postprandial meal volumes are accurately measured with MRI. MRI is a noninvasive technique to measure stomach volumes and volume changes in response to a meal. Volume changes in response to a meal measured with MRI correlate perfectly with those measured with the barostat device. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.     

Rectal hypersensitivity as hallmark for irritable bowel syndrome: defining the optimal cutoff

Background Visceral hypersensitivity is a frequently observed hallmark of irritable bowel syndrome (IBS). Studies have reported differently about the presence of visceral hypersensitivity in IBS resulting from lack of standardization of the barostat procedure and due to different criteria used to assess hypersensitivity. We aimed to calculate the optimal cutoff to detect visceral hypersensitivity in IBS. Methods A total of 126 IBS patients and 30 healthy controls (HC) were included for assessment of visceroperception by barostat. Pain perception was assessed on a visual analogue scale (VAS). ROC‐curves were used to calculate optimal discriminative cutoff (pressure and VAS‐score) between IBS patients and HC to define hypersensitivity. Furthermore, pain perception to distension sequences below the pressure threshold for hypersensitivity was defined as allodynia. Key Results Irritable bowel syndrome patients showed increased visceroperception compared to HC. Thresholds for first sensation and first pain were lower in IBS patients VS HC (P < 0.01). ROC‐curves showed optimal discrimination between IBS patients and HC at 26 mmHg with a VAS cutoff ≥20 mm. Using this criterion, hypersensitivity percentages were 63.5% and 6.6% in IBS patients and HC, respectively. No significant differences were observed between IBS subtypes. Allodynia was found in a small number of patients (11%). Conclusions & Inferences Optimal cutoff for visceral hypersensitivity was found at pressure 26 mmHg with a VAS ≥20 mm, resulting in 63.5% of IBS patients being hypersensitive and 11% being allodynic. Standardization of barostat procedures and defining optimal cutoff values for hypersensitivity is warranted when employing rectal barostat measurements for research or clinical purposes.     

Length and site of the small intestine exposed to fat influences hunger and food intake

The site of intestinal fat delivery affects satiety and may affect food intake in humans. Animal data suggest that the length of the small intestine exposed to fat is also relevant. The aim of the present study was to investigate whether increasing the areas of intestinal fat exposure and the way it is exposed would affect satiety parameters and food intake. In the present single-blind, randomised, cross-over study, fifteen volunteers, each intubated with a naso-ileal tube, received four treatments on consecutive days. The oral control (control treatment) was a liquid meal (LM) containing 6?g fat ingested at t?=?0?min, with saline infusion at t?=?30-120?min. Experimental treatments were a fat-free LM at t?=?0?min, with either 6?g oil delivered sequentially (2?g duodenal, t?=?30-60?min; 2?g jejunal, t?=?60-90?min; 2?g ileal, t?=?90-120?min), simultaneously (2?g each to all sites, t?=?30-120?min) or ileal only (6?g ileal, t?=?30-120?min). Satiety parameters (hunger and fullness) and cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1), peptide YY (PYY) secretion were measured until t?=?180?min, when ad libitum food intake was assessed. Only the ileum treatment reduced food intake significantly over the control treatment. The ileum and simultaneous treatments significantly reduced hunger compared with the control treatment. Compared with control, no differences were observed for PYY, CCK and GLP-1 with regard to 180?min integrated secretion. Ileal fat infusion had the most pronounced effect on food intake and satiety. Increasing the areas of intestinal fat exposure only affected hunger when fat was delivered simultaneously, not sequentially, to the exposed areas. These results demonstrate that ileal brake activation offers an interesting target for the regulation of ingestive behaviour.