Detection of hepatocellular carcinoma capsule by contrast-enhanced ultrasound using Levovist: correlations with pathological findings.

Abstract

To determine the most appropriate therapy for each hepatocellular carcinoma (HCC) nodule, it is important to ascertain whether the tumor has a capsule. The aim of this study was to investigate the diagnostic potential of contrast-enhanced ultrasound (CEUS) in HCC capsule detection by comparing ultrasound findings with histological results from operative specimens. Thirty-six HCC nodules (all smaller than 5 cm) from 36 patients who had undergone hepatectomy were examined by CEUS using Levovist with agent detection imaging. The vascular phase images and time course changes of HCC were observed after a bolus injection of Levovist. We classified the appearance of the tumor artery, tumor enhancement, and washout into several patterns. We grouped HCCs into encapsulated or nonencapsulated on the basis of the histology of the operative specimens, taking into account the effectiveness of transcatheter arterial chemoembolization. Ultrasound and pathological findings were compared to assess the ability of CEUS to detect HCC capsules. During the arterial phase, 12 (80.0%) encapsulated and 3 (14.3%) nonencapsulated HCC nodules showed a surrounding artery with branches pattern (P < 0.0001). The sensitivity, specificity, and accuracy of this pattern for HCC capsule detection were 80%, 86%, and 83%, respectively. A branching artery was found in 15 (71.4%) nonencapsulated but in only 3 (20.0%) encapsulated HCC nodules (P < 0.01). The sensitivity, specificity, and accuracy of this branching artery pattern for confirming the absence of a capsule in HCC nodules were 71%, 80%, and 75%, respectively. Almost all HCC nodules showed strong-moderate or weak enhancement and strong-moderate or mild washout. Neither enhancement nor washout pattern correlated with the presence of a capsule. The arterial phase of CEUS is very useful for detection of HCC capsules and therefore facilitates selection of the most appropriate treatment method for HCC.