Postprandial changes in gastrointestinal function and transit in cystic fibrosis assessed by magnetic resonance imaging

Background and Aims Cystic fibrosis (CF) is a multi-system genetic disorder affecting >72,000 people worldwide. Most people with CF experience gastrointestinal symptoms and some will develop complications such as distal intestinal obstruction syndrome. However the mechanisms of symptoms and complications are not understood. We evaluated gut function and transit of CF using magnetic resonance imaging (MRI). Our hypotheses were: oro-caecal transit time (OCTT) is longer in CF, with lower small bowel water content (SBWC). Methods Twelve people with CF at a tertiary centre and 12 age and sex-matched controls underwent serial MRIs over 1 day, with meals at set times. The primary endpoint was OCTT, assessed by the appearance of a food bolus in the caecum. Other measures included SBWC, colonic volume, gastric half-emptying time and gastrointestinal symptoms. Results OCTT was longer in CF (controls 210 minutes [173, 315] vs. CF 330 minutes [270, >360], p=0.04). There was no difference in gastric half-emptying times (controls 80 minutes [66, 88] vs. CF 97 [71, 128], p=0.3). Corrected SBWC was higher in CF (controls 34 L.min/m 2 [28, 41] vs. CF 63 L.min/m 2 [36, 80], p=0.021), with minimal second post-prandial decrease suggesting impaired ileal emptying. Corrected colonic volumes were higher in CF (controls 123 L.min/m 2 [89, 146] vs. CF 186 L.min/m 2 [166, 209], p=0.012). There were no differences in gastrointestinal symptoms. Conclusions Significant differences in gut function and transit exist between CF and controls. Our methodology provides a platform for studying gastrointestinal function in CF and has identified new potential mechanisms of dysfunction. ClinicalTrials.gov NCT03566550