title: Colonic response to laxative ingestion as assessed by MRI differs in constipated irritable bowel syndrome compared to functional constipation.
abstract: Functional constipation (FC) and irritable bowel syndrome with constipation (IBS-C) share many symptoms but underlying mechanisms may be different. We have developed a magnetic resonance imaging (MRI) technique to measure intestinal volumes, transit, and motility in response to a laxative, Moviprep(®) . We aim to use these biomarkers to study the pathophysiology in IBS-C and FC.
  
  
  
  Twenty-four FC and 24 IBS-C were studied. Transit was assessed using the weighted average position score (WAPS) of five MRI marker pills, taken 24 h before MRI scanning. Following baseline scan, participants ingested 1 L of Moviprep(®) followed by hourly scans. Magnetic resonance imaging parameters and bowel symptoms were scored from 0 to 4 h.
  
  
  
  Weighted average position score for FC was 3.6 (2.5-4.2), significantly greater than IBS-C at 2.0 (1.5-3.2), p = 0.01, indicating slower transit for FC. Functional constipation showed greater fasting small bowel water content, 83 (63-142) mL vs 39 (15-70) mL in IBS-C, p < 0.01 and greater ascending colon volume (AC), 314 (101) mL vs 226 (71) mL in IBS-C, p < 0.01. FC motility index was lower at 0.055 (0.044) compared to IBS-C, 0.107 (0.070), p < 0.01. Time to first bowel movement following ingestion of Moviprep(®) was greater for FC, being 295 (116-526) min, compared to IBS-C at 84 (49-111) min, p < 0.01, and correlated with AC volume 2 h after Moviprep(®) , r = 0.44, p < 0.01. Using a cut-off >230 min distinguishes FC from IBS-C with low sensitivity of 55% but high specificity of 95%.
  
  
  
  Our objective MRI biomarkers allow a distinction between FC and IBS-C.
authors.affiliation: NIHR Nottingham Digestive Diseases Biomedical Research Unit and Nottingham Digestive Diseases Centre, School of Medicine, University of Nottingham, Nottingham, UK.
authors.forename: C
authors.initials: C
authors.lastname: Lam
authors.affiliation: Sir Peter Mansfield Imaging Centre, University of Nottingham, Nottingham, UK.
authors.forename: G
authors.initials: G
authors.lastname: Chaddock
authors.affiliation: NIHR Nottingham Digestive Diseases Biomedical Research Unit and Nottingham Digestive Diseases Centre, School of Medicine, University of Nottingham, Nottingham, UK.
authors.forename: L
authors.initials: L
authors.lastname: Marciani
authors.affiliation: NIHR Nottingham Digestive Diseases Biomedical Research Unit and Nottingham Digestive Diseases Centre, School of Medicine, University of Nottingham, Nottingham, UK.
authors.forename: C
authors.initials: C
authors.lastname: Costigan
authors.affiliation: Sir Peter Mansfield Imaging Centre, University of Nottingham, Nottingham, UK.
authors.forename: J
authors.initials: J
authors.lastname: Paul
authors.affiliation: Sir Peter Mansfield Imaging Centre, University of Nottingham, Nottingham, UK.
authors.forename: E
authors.initials: E
authors.lastname: Cox
authors.affiliation: NIHR Nottingham Digestive Diseases Biomedical Research Unit and Nottingham Digestive Diseases Centre, School of Medicine, University of Nottingham, Nottingham, UK.|Sir Peter Mansfield Imaging Centre, University of Nottingham, Nottingham, UK.
authors.forename: C
authors.initials: C
authors.lastname: Hoad
authors.affiliation: Centre for Medical Imaging, Division of Medicine, University College London, London, UK.
authors.forename: A
authors.initials: A
authors.lastname: Menys
authors.affiliation: Sir Peter Mansfield Imaging Centre, University of Nottingham, Nottingham, UK.
authors.forename: S
authors.initials: S
authors.lastname: Pritchard
authors.affiliation: Royal Derby Hospitals Foundation Trust, Derby, UK.
authors.forename: K
authors.initials: K
authors.lastname: Garsed
authors.affiliation: Centre for Medical Imaging, Division of Medicine, University College London, London, UK.
authors.forename: S
authors.initials: S
authors.lastname: Taylor
authors.affiliation: Centre for Medical Imaging, Division of Medicine, University College London, London, UK.
authors.forename: D
authors.initials: D
authors.lastname: Atkinson
authors.affiliation: Sir Peter Mansfield Imaging Centre, University of Nottingham, Nottingham, UK.
authors.forename: P
authors.initials: P
authors.lastname: Gowland
authors.affiliation: NIHR Nottingham Digestive Diseases Biomedical Research Unit and Nottingham Digestive Diseases Centre, School of Medicine, University of Nottingham, Nottingham, UK.
authors.forename: R
authors.initials: R
authors.lastname: Spiller
mesh_terms: D000328:Adult; D003106:Colon / Q000000981:diagnostic imaging* / Q000187:drug effects; D003248:Constipation / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005260:Female; D005769:Gastrointestinal Motility / Q000187:drug effects / Q000502:physiology; D005772:Gastrointestinal Transit / Q000187:drug effects / Q000502:physiology; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000000981:diagnostic imaging* / Q000503:physiopathology; D054368:Laxatives / Q000008:administration & dosage*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D011092:Polyethylene Glycols / Q000008:administration & dosage*
chemical_list: D054368:Laxatives; C520497:MoviPrep; D011092:Polyethylene Glycols
keywords: colon; functional constipation; irritable bowel syndrome with constipation; laxative; motility