Hydatid disease: radiologic and pathologic features and complications

Hydatid disease primarily affects the liver and typically demonstrates char acteristic imaging findings. However, there are many potential local compli cations (eg, intrahepatic complications, exophytic growth, transdiaphragmat ic thoracic involvement, perforation into hollow viscera, peritoneal seedin g, biliary communication, portal vein involvement, abdominal wall invasion) . Furthermore, secondary involvement due to hematogenous dissemination may be seen in almost any anatomic location (eg, lung, kidney, spleen, bone, br ain). Ultrasonography (US) is particularly useful for the detection of cyst ic membranes, septa, and hydatid sand. Computed tomography (CT) best demons trates cyst wall calcification and cyst infection. CT and magnetic resonanc e (MR) imaging may demonstrate cyst wall defects as well as the passage of contents through a defect. Chest radiography, US, CT, and MR imaging are al l useful in depicting transdiaphragmatic migration of hydatid disease. CT i s the modality of choice in peritoneal seeding. US and CT demonstrate ruptu re in most cases that involve wide communication. Indirect signs of biliary communication include increased echogenicity at US and fluid levels and si gnal intensity changes at MR imaging. CT allows precise assessment of osseo us lesions, whereas AM imaging is superior in demonstrating neural involvem ent. Familiarity with atypical manifestations of hydatid disease may be hel pful in making a prompt, accurate diagnosis.