[Imaging and anatomical study of echinococcosis: CT and MR imaging in alveolar hydatid disease].

To elucidate the characteristics of alveolar hydatid disease on computed tomography (CT) and magnetic resonance imaging (MRI), a correlative radiologic-pathologic study was performed on fifteen rats after autopsy. The rate of lesion detection was higher for MRI (93%) than CT (77%). The preoperative CT scans of sixteen lesions in nine patients with surgically proved alveolar hydatid disease were reviewed retrospectively. Large lesions (> 5 cm in diameter) showed a soft tissue density area (50%), central necrosis with irregular thickened wall (33%), honeycomb appearance (50%) and calcification (100%). Small lesions (< 2 cm) showed only a small low density area. Confluent low density areas were pathognomonic for the early lesions. MR images were available in three patients. Enhanced MRI (SE 600/20) could show confluent low intensity areas and high intensity areas around the lesions caused by inflammation and edema, which could not be demonstrated well on CT. Metastatic lesions of lung and bone were also visualized on plain radiographs.