title: The challenge of segmental small bowel motility quantitation using MR enterography.
abstract: OBJECTIVE
  Analysis of "cine" MRI using segmental regions of interest (ROIs) has become increasingly popular for investigating bowel motility; however, variation in motility in healthy subjects both within and between scans remains poorly described.
  
  
  METHODS
  20 healthy individuals (mean age, 28 years; 14, males) underwent MR enterography to acquire dynamic motility scans in both breath hold (BH) and free breathing (FB) on 2 occasions. Motility data were quantitatively assessed by placing four ROIs per subject in different small bowel segments and applying two measures: (1) contractions per minute (CPM) and (2) Jacobian standard deviation (SD) motility score. Within-scan (between segment) variation was assessed using intraclass correlation (ICC), and repeatability was assessed using Bland-Altman limits of agreement (BA LoA).
  
  
  RESULTS
  Within-scan segmental variation: BH CPM and Jacobian SD metrics between the four segments demonstrated ICC R = 0.06, p = 0.100 and R = 0.20, p = 0.027 and in FB, the CPM and Jacobian SD metrics demonstrated ICC R = -0.26, p = 0.050 and R = 0.19, p = 0.030. Repeatability: BH CPM for matched segments ranged between 0 and 14 contractions with BA LoA of ±8.36 and Jacobian SD ranged between 0.09 and 0.51 with LoA of ±0.33. In FB data, CPM ranged between 0 and 10 contractions with BA LoA of ±7.25 and Jacobian SD ranged between 0.16 and 0.63 with LoA = ±0.28.
  
  
  CONCLUSIONS
  The MRI-quantified small bowel motility in normal subjects demonstrates wide intersegmental variation and relatively poor repeatability over time.
  
  
  CONCLUSIONS
  This article presents baseline values for healthy individuals of within- and between-scan motility that are essential for understanding how this process changes in disease.
authors.affiliation: Centre for Medical Imaging, University College London, UK.
authors.forename: A
authors.initials: A
authors.lastname: Menys
authors.forename: A
authors.initials: A
authors.lastname: Plumb
authors.forename: D
authors.initials: D
authors.lastname: Atkinson
authors.forename: S A
authors.initials: SA
authors.lastname: Taylor
mesh_terms: D000328:Adult; D005260:Female; D005769:Gastrointestinal Motility / Q000502:physiology*; D006801:Humans; D007421:Intestine, Small / Q000502:physiology*; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D012016:Reference Values