Original Contribution
The American Journal of Gastroenterology (2006) 101, 1551–1558; doi:10.1111/j.1572-0241.2006.00561.x
Computer-Assisted Evaluation of Perianal Fistula Activity by Means of Anal Ultrasound in Patients with Crohn's Disease
Flavio Caprioli MD1, Alessandra Losco MD1, Chiara Viganò MD1, Dario Conte MD1, Pietro Biondetti MD2, Laura V Forzenigo MD2 and Guido Basilisco MD1
- 1Post-graduate School of Gastroenterology and Digestive Endoscopy (I), University of Milan, Milan, Italy; Department of Gastroenterology, Endocrine and Metabolic Diseases, Milan, Italy
- 2Department of Imaging, Fondazione IRCCS Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, Milan, Italy
Correspondence: Guido Basilisco, MD, Fondazione IRCCS Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, Department of Gastroenterology and Endocrine and Metabolic Diseases Padiglione Granelli, Via F. Sforza 35, 20122, Milano, Italy.
Received 11 July 2005; Accepted 9 January 2006.
Abstract
OBJECTIVES:
Assessment of the activity of perianal fistulas may be of clinical relevance in patients with Crohn's disease. Fistula activity is currently evaluated by means of magnetic resonance imaging; anal ultrasound can also be used, but its diagnostic performance in this setting remains to be defined. Our aims were to evaluate the agreement between clinical examination, magnetic resonance imaging, and anal ultrasound in assessing perianal fistula activity, and to apply computerized analysis to improve the assessment of ultrasound images.
METHODS:
Thirty-one consecutive patients with Crohn's perianal fistulas underwent clinical examination, and magnetic resonance and anal ultrasound imaging. Active fistulas were defined as the presence of active drainage or signs of local inflammation on clinical examination, and the definition was confirmed by surgical examination. Activity was assessed on the basis of T2 hyperintensity on magnetic resonance imaging and the degree of hypoechogenicity on anal ultrasound; the anal ultrasound images were also analyzed using dedicated computer image-analysis software.
RESULTS:
Twenty-five patients had an active fistula at clinical examination. The agreement between clinical examination and magnetic resonance imaging was good (k-value = 0.739), whereas that with anal ultrasound was only fair (k-value = 0.266–0.294); computer-assisted analysis of the anal ultrasound images improved the agreement from fair to good (k-value = 0.608–0.670).
CONCLUSIONS:
Anal ultrasound can be used to assess fistula track activity in patients with Crohn's disease. The diagnostic performance of the technique can be improved to values comparable with those of magnetic resonance imaging by using a computer-assisted evaluation of the anal ultrasound images.
