title: MRI of small bowel Crohn's disease: determining the reproducibility of bowel wall gadolinium enhancement measurements.
abstract: This study aims to determine inter- and intra-observer variation in MRI measurements of relative bowel wall signal intensity (SI) in Crohn's disease. Twenty-one small bowel MRI examinations (11 male, mean age 40), including T1-weighted acquisitions acquired 30 to 120s post-gadolinium, were analysed. Maximal bowel wall SI (most avid, conspicuous contrast enhancement) in designated diseased segments was measured by two radiologists and two trainees using self-positioned "free" regions of interest (ROIs) followed by "fixed" ROIs chosen by one radiologist, and this procedure was repeated 1 month later. Relative enhancement (post-contrast SI minus pre-contrast SI/pre-contrast SI) was calculated. Data were analysed using Bland-Altman limits of agreement and intra-class correlation. Inter-observer agreement for relative enhancement was poor (spanning over 120%) using a free ROI-95% limits of agreement -0.69, 0.70 and -0.47, 0.74 for radiologists and trainees, respectively, only marginally improved by use of a fixed ROI -0.60, 0.67 and -0.59, 0.49. Intra-class correlation ranged from 0.46 to 0.72. Intra-observer agreement was slightly better and optimised using a fixed ROI-95% limits of agreement -0.52, 0.50 and -0.34, 0.28 for radiologists and trainees, respectively. Intra-class correlation ranged from 0.49 to 0.86. Relative bowel wall signal intensity measurements demonstrate wide limits of observer agreement, unrelated to reader experience but improved using fixed ROIs.
authors.affiliation: Ninewells Hospital, Dundee, UK.
authors.forename: A
authors.initials: A
authors.lastname: Sharman
authors.forename: I A
authors.initials: IA
authors.lastname: Zealley
authors.forename: R
authors.initials: R
authors.lastname: Greenhalgh
authors.forename: P
authors.initials: P
authors.lastname: Bassett
authors.forename: S A
authors.initials: SA
authors.lastname: Taylor
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D003287:Contrast Media; D003424:Crohn Disease / Q000175:diagnosis*; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007421:Intestine, Small / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D003287:Contrast Media; C064925:gadodiamide; D019786:Gadolinium DTPA