MRI assessment of the postprandial gastrointestinal motility and peptide response in healthy humans

Background: Feeding triggers inter-related gastrointestinal (GI) motor, peptide and appetite responses. These are rarely studied together due to methodological limitations. Recent MRI advances allow pan-intestinal, non-invasive assessment of motility in the undisturbed gut. This study aimed to develop a methodology to assess pan-intestinal motility and transit in a single session using MRI and compare imaging findings to GI peptide responses to a test meal and symptoms in a healthy volunteer cohort.

Methods: Fifteen healthy volunteers (29.3±2.7 years and BMI 20.1±1.2 kg m^-2 ) underwent baseline and postprandial MRI scans, symptom questionnaires, and blood sampling (for subsequent GI peptide analysis, Glucagon-like peptide-1 [GLP-1], Polypeptide YY [PYY], Cholecystokinin [CCK]) at intervals for 270 minutes following a 400 g soup meal (204 kcal, Heinz, UK). Gastric volume, gall bladder volume, small bowel water content, small bowel motility, and whole gut transit were measured from the MRI scans.

Key results: (mean±SEM) Small bowel motility index increased from fasting 39±3 arbitrary units (a.u.) to a maximum of 87±7 a.u. immediately after feeding. PYY increased from fasting 98±10 pg mL^-1 to 149±14 pg mL^-1 at 30 minutes and GLP-1 from fasting 15±3 μg mL^-1 to 22±4 μg mL^-1 . CCK increased from fasting 0.40±0.06 pmol mL^-1 to 0.94±0.1 pmol mL^-1 . Gastric volumes declined with a T_1/2 of 46±5 minute and the gallbladder contracted from a fasting volume of 19±2 mL^-1 to 12±2 mL^-1 . Small bowel water content increased from 39±2 mL^-1 to 51±2 mL^-1 postprandial. Fullness VAS score increased from 9±5 mm to 41±6 mm at 30 minutes postprandial.

Conclusions and inferences: The test meal challenge was effective in inducing a change in MRI motility end-points which will improve understanding of the pathophysiological postprandial GI response.