BACKGROUND:Contrast-enhanced ultrasonography(CEUS) is an important technique for depiction and assessment of tumor vascularity.This study aimed to explore the relationship between the morphological characteristics of tumor microvessels and enhancement patterns on CEUS in hepatocellular carcinoma (HCC). METHODS:Eighty patients with HCC underwent CEUS using SonoVue before hepatectomy.Contrast-enhanced ultrasonographic enhancement patterns and quantitative parameters were recorded.The tumor tissue sections were immunostained with human CD34 monoclonal antibody.The patients were classified into a point-line type group(n=36)and a loop-strip type group(n=44)according to microvessel morphology. The microvascular density(MVD)in the different types of microvessels was calculated.The relationship between enhancement patterns of HCC lesions and morphological characteristics of tumor microvessels was analyzed. RESULTS:The mean MVD in HCC was 22.4±3.5 per 0.2 mm 2 in the point-line group,and 19.6±6.7 per 0.2 mm 2 in the loop-strip group,and there was no significant difference between them(t=0.948,P=0.354).In the portal vein phase, hypoenhancement was significantly more frequent in HCC (χ2=4.789,P=0.029)in the loop-strip group(40/44,90.9%) than in the point-line group(26/36,72.2%).The time to hypoenhancement in the loop-strip group(mean 64.84±26.16 seconds)was shorter than that in the point-line group(mean 78.39±28.72 seconds)(t=2.247,P=0.022).The time to hypoenhancement was correlated with MVD in the loop-strip group(r=-0.648,P=0.001).CONCLUSIONS:The enhancement patterns on CEUS are related to tumor microvascular morphology,and the type of microvascular morphology influences CEUS characterization. CEUS,an important noninvasive imaging technique,is used to evaluate microvascular morphology and angiogenesis,providing valuable information for antiangiogenic therapy in HCC.