Real-time Interobserver Agreement in Bowel Ultrasonography for Diagnostic Assessment in Patients With Crohn's Disease: An International Multicenter Study

Background: The unavailability of standardized parameters in bowel ultrasonography (US) commonly used in Crohn's disease (CD) and the shortage of skilled ultrasonographers are 2 limiting factors in the use of this imaging modality around the world. The aim of this study is to evaluate interobserver agreement among experienced sonographers in the evaluation of bowel US parameters in order to improve standardization in imaging reporting and interpretation. Methods: Fifteen patients with an established diagnosis of CD underwent blinded bowel US performed by 6 experienced sonographers. Prior to the evaluation, the sonographers and clinical and radiological IBD experts met to formally define the US parameters. Interobserver agreement was tested with the Quatto method (s). Results: All operators agreed on the presence/absence of CD lesions and distinguished absence of/mild activity or moderate/severe lesions in all patients. S values were moderate for bowel wall thickness (s = 0.48, P = n.s.), bowel wall pattern (s = 0.41, P = n.s.), vascularization (s = 0.52, P = n.s.), and presence of lymphnodes (s = 0.61, P = n.s.). Agreement was substantial for lesion location (s = 0.68, P = n.s.), fistula (s = 0.74, P = n.s.), phlegmon (s = 0.78, P = 0.04), and was almost perfect for abscess (s = 0.95, P = 0.02). Poor agreement was observed for mesenteric adipose tissue alteration, lesion extent, stenosis, and prestenotic dilation. Conclusions: In this study, the majority of the US parameters used in CD showed moderate/substantial agreement. The development of shared US imaging interpretation patterns among sonographers will lead to improved comparability of US results among centers and facilitate the development of multicenter studies and the spread of bowel US training, thereby allowing a wider adoption of this useful technique.