title: Measuring the interaction of meal and gastric secretion: a combined quantitative magnetic resonance imaging and pharmacokinetic modeling approach.
abstract: BACKGROUND
  The stimulation and intragastric accumulation of gastric secretion has been recognized as an important factor in gastroesophageal reflux disease. However, the interaction of gastric secretion and meal emptying has not been fully understood. Current methods to assess gastric secretion are either invasive or unable to provide information on its volume, distribution and dynamics. The aim of this study was to quantify the interaction between meal emptying and meal induced gastric secretion by using quantitative magnetic resonance imaging (MRI) and pharmacokinetic analysis.
  
  
  METHODS
  A chocolate test meal was developed which is secretion stimulating and MRI compatible. Meal emptying and gastric secretion were assessed in fourteen healthy volunteers using a validated quantitative MRI technique. A population based pharmacokinetic model was developed and applied to the extracted volume data, assessing the meal emptying rate, rate of secretion and their interaction.
  
  
  RESULTS
  The test meal continuously induced gastric secretion in all subjects, which partly accumulated at the meal-air interface, forming a 'secretion layer' in the proximal stomach. Traditional fitting detected a significant correlation between meal emptying rate and rate of secretion. The pharmacokinetic model quantified this interaction and estimated a 2.3 ± 1 fold higher effect of meal on secretion than vice versa. The efficacy of the emptied meal to produce gastric secretion was 61%.
  
  
  CONCLUSIONS
  The combined quantitative MRI and pharmacokinetic model approach allows for the quantification of gastric secretion volume and its interaction on meal emptying. The observed secretion layer might explain previous findings postulating the presence of an intragastric 'acid pocket'.
authors.affiliation: Division of Gastroenterology and Hepatology, University of Zurich, Zurich, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Sauter
authors.forename: J
authors.initials: J
authors.lastname: Curcic
authors.forename: D
authors.initials: D
authors.lastname: Menne
authors.forename: O
authors.initials: O
authors.lastname: Goetze
authors.forename: M
authors.initials: M
authors.lastname: Fried
authors.forename: W
authors.initials: W
authors.lastname: Schwizer
authors.forename: A
authors.initials: A
authors.lastname: Steingoetter
mesh_terms: D000328:Adult; D004435:Eating / Q000502:physiology; D005260:Female; D005746:Gastric Emptying / Q000502:physiology*; D005750:Gastric Juice / Q000378:metabolism*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D013270:Stomach / Q000502:physiology*