MRI of Fistula In Ano: Inter- and Intraobserver Agreement and Effects of Directed Education

• Published in: American journal of roentgenology (1976) Vol. 183; no. 1; pp. 135 - 140
• Main Authors: Buchanan, Gordon N, Halligan, Steve, Taylor, Stuart, Williams, Andrew, Cohen, Richard, Bartram, Clive
• Format: Journal Article
• Language: English
• Published: Leesburg, VA Am Roentgen Ray Soc 01.07.2004; American Roentgen Ray Society
• Subjects: Adult; Biological and medical sciences; Female; Humans; Investigative techniques, diagnostic techniques (general aspects); Magnetic Resonance Imaging - statistics & numerical data; Male; Medical sciences; Observer Variation; Prospective Studies; Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects); Rectal Fistula - diagnosis; Rectal Fistula - epidemiology; Radiology; Nuclear medicine; Medical imagery; Fistula; Education; Nuclear magnetic resonance imaging
• ISSN: 0361-803X; 1546-3141
• DOI: 10.2214/ajr.183.1.1830135

Preoperative MRI of fistula in ano is becoming more common. This prospective study aimed to determine if a significant difference occurred in interpretation between one expert and one novice observer and to assess inter- and intraobserver agreement after both observers underwent a period of directed education. SUBJECTS AND METHODS. An outcome-derived reference standard was defined in 100 patients with suspected fistula in ano via a combination of preoperative MRI, surgical findings, and clinical outcome. The performances of a single expert and a single novice interpreter were compared with this reference standard both before and after a period of directed education, and inter- and intraobserver agreement was determined. Initially the expert correctly classified significantly more fistulas than the novice (85% vs 63%, p = 0.024), but after directed education there was no significant difference, with good agreement for both the classification of the primary track (kappa = 0.71) and identification of extensions (k = 0.61). Intraobserver agreement was very good for the expert (kappa = 0.92) and novice (kappa = 0.88) for classification of the primary track and good (kappa = 0.64 and 0.74, respectively) for identification of extensions. The diagnostic accuracy for fistula in ano classification using MRI was significantly higher for one expert than for one novice, though this was rectified by a short period of directed education.