Abstract: Objective To investigate the value of the contrast enhanced ultrasound (CEUS) combined with immunohistochemistry (IHC) in preoperative diagnosis of microvascular invasion (MVI) of small hepatocellular carcinoma (HCC). Methods The data of 142 HCC patients, including 177 newly developed HCC lesions with a maximum diameter of no more than 3 cm were retrospectively collected from the Yokohama City University Medical Center of Japan and the First Affiliated Hospital of Xi'an Jiaotong University. According to the pathological diagnosis, the patients were divided into MVI (+) group (n=37) and MVI (-) group (n=140). Preoperative CEUS arterial phase (AP) and post-vascular phase (PVP) images were used to observe whether there was hypervascularity and hypovascularity around the lesion. The expressions of heat shock protein 70 (HSP70) and glypican 3 (GPC3) in preoperative biopsy samples were detected by IHC method. Results When all CEUS indicators (AP, PVP) and IHC indicators (GPC3, HSP70) were diagnosed MVI individually, PVP had the highest diagnostic efficiency, with an accuracy of 91.0% and an area under the curve (AUC) of 0.893. The diagnostic efficiency of GPC3 combined with HSP70 (accuracy: 79.8%, AUC: 0.790) was better than that of GPC3 alone (accuracy: 69.5%, AUC: 0.752) or HSP70 alone (accuracy: 60.7%, AUC: 0.701). The combined diagnosis of PVP+GPC3+HSP70 had the best diagnostic efficiency, with a specificity of 98.5%, an accuracy of 92.5%, and an AUC of 0.840. Conclusions Observing the PVP of CEUS and using IHC to detect the expressions of GPC3 and HSP70 can better diagnose the MVI of small HCC preoperatively.

Key words: Hepatocellular carcinoma, Microvascular invasion, Contrast enhanced ultrasound, Immunohistochemistry, Diagnosis