Sonographic diagnosis of hydatidosis: the sign of the cyst wall.

The Authors evaluate the diagnostic accuracy of echography in hepatic echinococcosis, particularly in the completely liquid types of cysts without septa or hydatid sand and in the solidified forms where the differential diagnosis with other hepatic pathologies can be difficult. The study was carried out with a 7.5 MHz probe and the results were compared with those from the use of a 3.5 MHz probe and from CT, serology for hydatidosis and echoguided sampling. Seventy one patients, 36 with liquid hepatic lesions and 35 with solid hepatic lesions (31 hydatid and 40 non-parasitic), were evaluated echographically, first with a 3.5 MHz probe and subsequently with a 7.5 MHz probe. All the patients underwent serology for hydatidosis. All the liquid lesions were subjected to percutaneous echoguided aspiration and all the solid lesions to CT; echoguided biopsy was performed in only 24 of the latter lesions. With the 7.5 MHz probe, a wall was revealed in 96.77% of parasitic cysts but in only 5% of non-hydatid ones. Moreover, using the 7.5 MHz probe, it was possible to see a triple-layered aspect of the wall in the hydatid cysts. The results obtained with the 7.5 MHz probe demonstrate a high diagnostic accuracy comparable to that of MR.