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The principal sonographic signs of alveolar hydatid disease elaborated by Weill are as follows:

Hepatomegaly
Hyperechoic foci
Calcifications
Cystic, often craggy, necrosis
Dilatation of the biliary tree
Deformity and narrowing of the portal and hepatic veins

The following CT findings and staging of hepatic alveolar echinococcosis, adapted from Rozanes et al (1995) (Fig. 3.169), correlate well with the surgical findings and seem to be useful for therapeutic planning.

Stage 1. Lesion measuring less than 3 cm in diameter;
Stage 2. Lesion greater than 3 cm, confined to less than 3 hepatic segments;
Stage 3a. Lesion with invasion of more than 3 hepatic segments;
Stage 3b. Invasion of the liver hilum or suprahepatic vena cava;
Stage 4. Invasion of surrounding organs and/or distant metastases.

As noted above, the ultrasound and CT findings of hepatic alveolar hydatidosis include hepatomegaly and heterogeneous geographic invading lesions with irregular margins. On contrast-enhanced CT, these present as low-density masses which may be combined with amorphous or nodular calcifications (Fig. 3.169). This pattern may suggest alveolar hydatidosis rather than hepatocellular carcinoma, but biopsy of the lesions is often required to exclude hepatic malignancy: no complications have been reported in those cases where fine-needle aspiration biopsy was performed.

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Fig. 3.169 CT staging of alveolar hydatid disease of the liver in multiple patients. (A) Stage 2 lesion with several calcific foci and large pseudocystic zone confined to the lateral segment of the left liver lobe. (B) Stage 3a lesion with multiple calcifications, pseudocystic necrotic areas, and invasion of more than 3 hepatic segments. (C) Stage 3b lesion with invasion of the inferior vena cava. (D) Same patient with tumor thrombus in the suprahepatic vena cava extending into the right atrium (arrow). (E) Stage 3b lesion with invasion of the liver hilum. Dilatation of intrahepatic bile ducts in both lobes of the liver is present, as well as lymphadenopathy in the liver hilum (arrow). (F) Stage 4 lesion with invasion of the liver dome associated with multiple pulmonary and pleural metastases (arrows). (G) Numerous pulmonary metastatic nodules are seen in the lung window. (H) Another patient with a stage 4 lesion with numerous mottled calcific foci and prominent rim calcification in the right lobe of the liver. (I) Metastasis to the T12 vertebra with bony destruction, invasion of the epidural space, and paravertebral soft tissue thickening and calcification. Two E. multilocularis nodules are present in the left liver lobe (arrows). (Courtesy of Dr. I. Rozanes and Eur Radiol, 1995).

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