Prospective assessment of interobserver agreement for endoanal MRI in fecal incontinence

Background: Endoanal magnetic resonance (MR) imaging is a new technique for the assessment of anal sphincter integrity in fecal incontinence and an alternative to anal endosonography. The present study aimed to determine interobserver variation for assessment of anal sphincter integrity using endoanal MR imaging. Methods: Fifty-two consecutive anally incontinent patients underwent MR imaging by using a purpose-built endoanal receiver coil and static 1.0-T magnet. T2-weighted axial, coronal, and sagittal scans were independently assessed by two radiologists who noted external and internal sphincter integrity. Findings were compared and agreement was assessed with the kappa statistic. Results: There was disagreement in 18 of 49 technically adequate studies (37%; kappa = 0.46), indicating "moderate" agreement. Agreement was strongest if the sphincters were either both intact or both disrupted. Observers agreed in only one diagnosis of an isolated internal sphincter defect and in no diagnosis of an isolated external sphincter defect. Conclusion: The overall interobserver agreement for assessment of sphincter integrity using endoanal MR imaging is "moderate." Interobserver agreement using endoanal MR imaging is less than that reported for anal endosonography.