title: Active Crohn disease: CT findings and interobserver agreement for enteric phase CT enterography.
abstract: OBJECTIVE
  To retrospectively evaluate small-bowel enhancement characteristics and the sensitivity, specificity, and interobserver agreement of computed tomographic (CT) findings by using histologic and endoscopic results as a reference standard in patients undergoing enteric phase CT enterography.
  
  
  METHODS
  The institutional review board approved this retrospective HIPAA-compliant study, which included patients who consented to having their medical records used for research purposes. Enteric phase CT enterographic and ileoscopic findings with or without ileal histologic results were examined in 42 patients (24 women, 18 men). Enteric phase CT enterography was performed after 150 mL of intravenous contrast material was administered at 4 mL/sec, with a 45-second delay. Mural attenuation was measured in the distended and collapsed jejunal and ileal loops and in the terminal ileum. Two radiologists examined CT images for findings of Crohn disease. Mural attenuation for different bowel loops was compared by using a Student t test, with kappa statistics used to measure interobserver agreement and Pearson correleation coefficients used to compare visual and quantitative measures.
  
  
  RESULTS
  Distended jejunal loops had significantly greater attenuation than distended ileal loops (113 HU vs 72 HU; P < .001). Attenuation of collapsed jejunal (134 HU) and ileal (108 HU) loops was greater than that of distended jejunal and ileal loops (P < .001). Terminal ileal enhancement was the most sensitive visual CT finding of Crohn disease for both radiologists. Mural thickening demonstrated the greatest interobserver agreement (kappa = 0.83). Visual enhancement and quantitative mural attenuation were significantly correlated (P < .003).
  
  
  CONCLUSIONS
  At enteric phase CT enterography, jejunal attenuation is greater than ileal attenuation and collapsed bowel loops demonstrate greater attenuation than distended bowel loops. Mural hyperenhancement and increased mural thickness are the most sensitive CT findings of active Crohn disease.
authors.affiliation: Department of Radiology, Mayo Clinic College of Medicine, 200 First St SW, Rochester, MN 55905, USA.
authors.forename: Fargol
authors.initials: F
authors.lastname: Booya
authors.forename: Joel G
authors.initials: JG
authors.lastname: Fletcher
authors.forename: James E
authors.initials: JE
authors.lastname: Huprich
authors.forename: John M
authors.initials: JM
authors.lastname: Barlow
authors.forename: C Daniel
authors.initials: CD
authors.lastname: Johnson
authors.forename: Jeff L
authors.initials: JL
authors.lastname: Fidler
authors.forename: Craig A
authors.initials: CA
authors.lastname: Solem
authors.forename: William J
authors.initials: WJ
authors.lastname: Sandborn
authors.forename: Edward V
authors.initials: EV
authors.lastname: Loftus
authors.forename: William S
authors.initials: WS
authors.lastname: Harmsen
mesh_terms: D000328:Adult; D016009:Chi-Square Distribution; D003287:Contrast Media; D003424:Crohn Disease / Q000000981:diagnostic imaging*; D016099:Endoscopy, Gastrointestinal; D005260:Female; D006801:Humans; D007421:Intestine, Small / Q000000981:diagnostic imaging*; D007472:Iohexol; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol