title: Noninvasive automated motion assessment of intestinal motility by continuously tagged MR imaging.
abstract: OBJECTIVE
  To evaluate continuously tagged 3 Tesla MRI for monitoring glucagon-induced bowel motility changes in healthy volunteers.
  
  
  METHODS
  After standardized oral bowel preparation, 10 healthy volunteers underwent a free-breathing, continuously tagged three-dimensional (3D) dynamic fast-field-echo (FFE), at a 3.36 Hz sampling frequency. One milligram of glucagon was administered intravenously during data acquisition. Each dataset was divided into four temporal sets of 2 min (period 1 to 4). Taglines were tracked automatically using a scale spaced based algorithm. Assessment of global spectral resolution was performed for three frequency intervals: 0.008-0.300 Hz (motility), 0.300-0.400 Hz (breathing motion), and 0.400-0.533 Hz (higher order motion). Additional analyses were performed at fine spectral resolution in frequency bands of 0.033 Hz. Glucagon-induced motility changes were investigated by means of a motility index (spectral power normalized to the maximal spectral power per-volunteer), resulting in a range of 0 to 1 (no motion to maximal motion). Statistical comparison was done for period 1 and 4 (Wilcoxon-signed rank test).
  
  
  RESULTS
  After glucagon administration, a significant decrease in the motility index was found for the low- (0.008-0.300 Hz) (P < 0.0001) and high-frequency interval (0.400-0.533 Hz) (P < 0.0001). Around breathing motion frequencies, no decrease in motility index was detected.
  
  
  CONCLUSIONS
  Free-breathing, continuously tagged MR imaging is a noninvasive method for automated bowel motility assessment and allows for detection of drug-induced changes.
authors.affiliation: Department of Radiology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.
authors.forename: Marije P
authors.initials: MP
authors.lastname: van der Paardt
authors.forename: André M J
authors.initials: AM
authors.lastname: Sprengers
authors.forename: Frank M
authors.initials: FM
authors.lastname: Zijta
authors.forename: Rolf
authors.initials: R
authors.lastname: Lamerichs
authors.forename: Aart J
authors.initials: AJ
authors.lastname: Nederveen
authors.forename: Jaap
authors.initials: J
authors.lastname: Stoker
mesh_terms: D000328:Adult; D000465:Algorithms; D001331:Automation; D005260:Female; D005769:Gastrointestinal Motility / Q000502:physiology*; D005934:Glucagon / Q000737:chemistry; D064368:Healthy Volunteers; D006801:Humans; D021621:Imaging, Three-Dimensional; D007422:Intestines / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D009038:Motion; D011446:Prospective Studies; D012016:Reference Values; D055815:Young Adult
chemical_list: D005934:Glucagon
keywords: MRI; bowel motility; continuously tagged MR imaging; glucagon; peristaltic motion