MR imaging for diagnosing cysto-biliary fistulas in cystic echinococcosis.

OBJECTIVE: To evaluate the sensitivity and specificity of magnetic resonance imaging (MR imaging) including MR cholangiography for the identification of cysto-biliary fistulas in patients with hepatic hydatid disease.

PATIENTS AND METHODS: Retrospective analysis of 3 groups of patients (20 patients with 51 echinococcal cysts) in a cohort of 103 patients with cystic echinococcosis with different pretest probabilities for cysto-biliary fistulas. Patients who had MR imaging/MR cholangiography with symptoms and signs of biliary obstruction (5 patients with 16 cysts, group I), before surgery for other reasons than biliary obstruction (9 patients with 14 cysts, group II) and for cyst staging (6 patients with 21 cysts, group III). All MR images were evaluated before surgery for the presence of cyst wall defects and hydatid debris in bile ducts. In groups I and II MR results were compared with surgical, parasitological, and biochemical findings of each individual cyst.

RESULTS: Based on direct (i.e. defects in the cyst wall and continuity of dilated biliary ducts into adjacent cysts), and indirect MR imaging/MR cholangiography imaging signs (i.e. intraluminal debris) our best estimate of sensitivity and specificity (stage-specific, WHO type CE3 and CE4) for cysto-biliary fistulas was 75% and 95%, respectively.

CONCLUSIONS: MR imaging with MR cholangiography is a valuable non-invasive imaging technique to assess the risk of cysto-biliary fistula-related complications and for planning of surgery.