Abstract: Objective  To correlate the characteristic images of hepatic alveolar echinococcosis （HAE） in rats using contrast-enhanced ultrasonography （CEUS） and microvascular density （MVD） in the surrounding invasion range of HAE lesions.  Methods  Thirty Wistar rats were infected with Echinococcus multolocularis suspension （approximately 800 protoscoleces in 0.2 ml per rat） through abdominal opening injection in liver. Three months after the inoculation, rats with hepatic E. multilocularis infection were examined by conventional and contrast-enhanced ultrasonography. The location, size, shape, boundary, inner echogenicity, and blood flow of the lesions, signal intensity and dynamic enhancement pattern were recorded. The positive rats were sacrificed and their livers were obtained. The structure of HAE lesions was observed by HE staining. Immunohistochemistry staining was performed on the infiltrative region of HAE lesion and the expression of CD34 in the surrounding hepatic parenchyma. Scoring was based on the percentage of positively stained cells and stain intensity. The correlation of MVD and the characteristic images of HAE using CEUS was analyzed.  Results  Twenty-three Wistar rats with hepatic E. multilocularis infection were killed, and 27 HAE lesions was found. The largest diameter of HAE lesion was 2.24 cm, and the average size was（0.97±0.48） cm. The shape of HAE lesions was round, oval, or irregular. HAE lesions presented a complex internal echo pattern. Spot-like color flow signal was observed in the tissues around the lesions, no blood flow signal was observed in HAE lesions. In 25 lesions, a circular rim-like enhancement belt was visualized at the periphery during early arterial phase, and honeycomb enhancement appeared in the other two lesions. The positive expression rate of CD34 in infiltrative zones surrounding HAE lesions was 99.2% （118/119）, with 17.6% （21/119） of strong positive, 73.1% （87/119） of moderate positive, 8.4% （10/119） of weak positive, and 0.8% （1/119） of negative, respectively. In normal liver tissues, the positive expression rate of CD34 was 25.2% （30/119）, no strong positive was found, with 4.2% （5/119） of moderate positive, 21.0% （25/119） of weak positive, and 74.8% （89/119） of negative, respectively. The sonographic infiltrative region in HAE lesion correlated with microvascular density （r=0.238， P＜0.05）.  Conclusion  There is a positive correlation between the circular rim-like enhancement belt surrounding HAE lesions and the microvascular density in the rat model.

Key words: Ultrasonography；Contrast medium；Sonovue®, ；Alveolar echinococcosis；Liver；Microvascular density