title: Comparison of noncontrast MRI magnetization transfer and T2 -Weighted signal intensity ratios for detection of bowel wall fibrosis in a Crohn's disease animal model.
abstract: OBJECTIVE
  To compare the abilities of magnetization transfer magnetic resonance imaging (MT-MRI) and T2 -weighted signal intensity (T2 WSI) ratios to detect intestinal fibrosis in a Crohn's disease animal model.
  
  
  METHODS
  Ten rats ("Group 1") received one trinitrobenzenesulfonic acid enema to induce acute colonic inflammation, while 10 additional animals ("Group 2") received multiple enemas to induce colonic inflammation and fibrosis. Gradient recalled-echo MT-MRI (5 and 10 kHz off-resonance) and T2 -weighted spin-echo imaging were performed 2 days after the last enema. MT ratios (MTR) and T2 WSI ratios were calculated in the area of greatest colonic thickening. Bowel wall MTR, bowel wall MTR normalized to paraspinous muscle MTR ("normalized MTR"), and T2 WSI ratios were compared between animal groups using Student's t-test.
  
  
  RESULTS
  At 10 kHz off-resonance, mean bowel wall MTR for Group 1 was 24.8 ± 3.1% vs. 30.3 ± 3.2% for Group 2 (P = 0.001). Mean normalized MTR was 0.45 ± 0.05 for Group 1 and 0.58 ± 0.08 for Group 2 (P = 0.0003). At 5 kHz off-resonance, mean bowel wall MTR for Group 1 was 34.7 ± 5.2% vs. 40.3 ± 3.6% for Group 2 (P = 0.015). Mean normalized MTR was 0.53 ± 0.08 for Group 1 and 0.64 ± 0.07 for Group 2 (P = 0.003). Mean T2 WSI ratio was 5.32 ± 0.98 for Group 1 and 3.01 ± 0.66 for group 2 (P < 0.0001). Mean T2 WSI ratio/MTR (10 kHz off-resonance) was 12.06 ± 2.70 for Group 1 and 5.22 ± 1.29 for Group 2 (P < 0.0001), with an ROC c-statistic of 0.98.
  
  
  CONCLUSIONS
  MTR and T2 WSI ratios detect bowel wall fibrosis in a Crohn's disease animal model.
authors.affiliation: Section of Pediatric Radiology, Department of Radiology, University of Michigan Health System, Ann Arbor, Michigan, USA.
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Dillman
authors.affiliation: Department of Radiology, University of Michigan Health System, Ann Arbor, Michigan, USA.
authors.forename: Scott D
authors.initials: SD
authors.lastname: Swanson
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, University of Michigan Health System, Ann Arbor, Michigan, USA.
authors.forename: Laura A
authors.initials: LA
authors.lastname: Johnson
authors.affiliation: Department of Pathology, University of Michigan Health System, Ann Arbor, Michigan, USA.
authors.forename: David S
authors.initials: DS
authors.lastname: Moons
authors.affiliation: Division of Pediatric Gastroenterology, Department of Pediatrics, University of Michigan Health System, Ann Arbor, Michigan, USA.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Adler
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, University of Michigan Health System, Ann Arbor, Michigan, USA.
authors.forename: Ryan W
authors.initials: RW
authors.lastname: Stidham
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, University of Michigan Health System, Ann Arbor, Michigan, USA.
authors.forename: Peter D R
authors.initials: PD
authors.lastname: Higgins
mesh_terms: D000818:Animals; D003094:Collagen / Q000737:chemistry; D003106:Colon / Q000473:pathology; D003424:Crohn Disease / Q000503:physiopathology*; D004195:Disease Models, Animal; D005355:Fibrosis; D007249:Inflammation / Q000473:pathology; D007413:Intestinal Mucosa / Q000473:pathology; D007422:Intestines / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D012372:ROC Curve; D051381:Rats; D011917:Rats, Inbred Lew; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D014302:Trinitrobenzenesulfonic Acid / Q000737:chemistry
chemical_list: D014302:Trinitrobenzenesulfonic Acid; D003094:Collagen
keywords: Crohn's disease; T2-weighted imaging; animal model; intestinal fibrosis; magnetic resonance imaging; magnetization transfer; quantitative imaging