To evaluate diagnostic performance of real-time tissue elastography (RTE) with a low frequency convex array probe for distinguishing benign from malignant hepatic tumors through trans-abdominal examination, elasticity images of 210 liver tumors were obtained by EUB-7500 (Hitachi Medical Systems and 3.5？MHz probe) and eventually 121 liver tumors were analyzed in the study. Elasticity images were classified into four types, from type a to d. Regarding type a or b as benign tumors and type c or d as malignant ones, sensitivity, specificity, and accuracy were calculated and the consistency between the findings of RTE and the pathohistological diagnosis was evaluated. The sensitivity, specificity, and accuracy were separately 97.2%, 88.0%, and 93.4% ( ). Moreover, there was a good consistency between the findings of RTE and the pathological diagnosis (kappa value 0.86). Among elasticity images of all the malignant tumors, the hepatocellular carcinomas (HCCs) mainly appeared in type c, and liver metastatic cancers in type d. Thus, RTE utilized as a novel noninvasive imaging examination method enables us to distinguish benign from malignant liver tumors. Moreover, it provides certain information for the differential diagnosis between HCCs and liver metastatic cancers. 1. Introduction The accurate differential diagnosis for hepatic benign and malignant tumors, including that between hepatocellular carcinomas (HCCs) and liver metastatic cancers, is a significant factor for whether the patient ought to receive an operation. Among the noninvasive diagnosis methods, real-time tissue elastography (RTE) has been paid more attention because its specific principle differs from other methods. The image of RTE is analyzed according to the stiffness of lesion tissue, closer to the pathohistological diagnosis of the lesion, enabling us to acquire information more objective and accurate about the liver tumors. The tissue shape will change once compressed. The difference of change can respond to the differential strain of the tissue and then be colored in the imaging system. Two types of compression could be accessible in practical operation. The one is outer compression from the probe while the other is inner compression from rhythmic beating of heart [1, 2]. Recently RTE has already been applied to the clinical practice as a promising imaging method in the diagnosis of some superficial tumors such as breast cancer [3, 4], thyroid cancer [5, 6], and prostate cancer [7, 8]. However, its application was limited in deep tumors such as liver tumors due to the low tissue
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