Assessment of the accuracy of preoperative imaging methods in the diagnosis of hepatic single-chamber echinococcosis

UNLABELLED: Echinococcosis is an infectious disease, caused by larval stages of cestode species of the genus Echinococcus. The course of the disease is determined on the basis of the location and larval size. In 80-95% of cases echinococcosis is located in the liver and lungs, rarely in the brain. Symptoms are usually uncharacteristic for an uncomplicated disease. The diagnosis of echinococcosis is based on imaging and immunodiagnostic tests. The aim of the study was to assess the accuracy of preoperative imaging methods in the diagnosis of hepatic single- chamber echinococcosis. MATERIAL AND METHODS: Amongst the 110 patients with hepatic cysts diagnosed during the period between 2000 and 2009, a group of 30 subjects with suspicion of single-chamber echinococcosis (ultrasound and CT) was isolated. The imaging methods visualized structures typical for hydatid cysts: the mother cyst with satellite cysts called " honeycomb appearance", cysts with calcified walls and compartments, and endocyst separation called "water lily-sign". The study group comprised 22 female and 8 male patients with an average age of 52±16.2 years. The histopathological examination of the excised cyst verified the diagnosis. RESULTS: Single-chamber echinococcosis was finally recognized in 19 cases, while in the 11 remaining cases the parasitic disease was excluded. The sensitivity of imaging methods was estimated at 73.7%, specificity - 88.9%, negative predictive value - 61.5%, positive predictive value - 93.3%, Youden`s factor - 0.626, and Φ index - 0.586. CONCLUSIONS: In conclusion, the presence of an unilocular cyst with an uniform anechoic content can be a simple cyst or single-chamber echinococcus cyst. The typical, characteristic image of a hydatid cyst, such as the "water lily-sign" is rarely observed during imaging examinations. It has also been shown that cystic calcification, observed during ultrasonography and computed tomography was evidence of the parasitic character of the lesion.