Contribution of Contrast-Enhanced Sonography With Perfluorobutane Microbubbles for Diagnosis of Recurrent Hepatocellular Carcinoma

Objectives-The role of contrast-enhanced sonography in the diagnosis of recurrent hepatocellular carcinoma is still unclear. This study aimed to clarify the usefulness and limitations of contrast-enhanced sonography with a perfluorobutane microbubble contrast agent (Sonazoid; Daiichi-Sankyo, Tokyo, Japan) after contrast-enhanced computed tomography (CT) for diagnosis of recurrent hepatocellular carcinoma and to establish its optimal use. Methods-A total of 514 patients, who were suspected to have recurrent hepatocellular carcinoma on contrast-enhanced CT, underwent contrast-enhanced sonography. Of 514 suspicious lesions, 484 were diagnosed as recurrent hepatocellular carcinomas, including 142 recurrent hepatocellular carcinomas measuring 1 cm or smaller in diameter. The largest lesion was evaluated in each patient. A final diagnosis of recurrent hepatocellular carcinoma after contrast-enhanced CT was reached on the basis of the typical hallmarks of hepatocellular carcinoma on any of the other contrast imaging modalities or by resected tissue or tumor enlargement during follow-up. Results-The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of contrast-enhanced CT were 68%, 93%, 99%, 15%, and 70%, respectively, and the values of contrast-enhanced sonography were 91%, 100%, 100%, 31%, and 91%, excluding 60 unassessable lesions on contrast-enhanced sonography. The diagnostic rate for recurrent hepatocellular carcinoma on contrast-enhanced sonography for lesions with an atypical enhancement pattern on contrast-enhanced CT was 71%. On multivariate analysis of factors contributing to the unassessability of contrast-enhanced sonography, lesion size, location, and abdominal wall thickness were independent factors. Conclusions-Although the assessability of contrast-enhanced sonography depends on lesion size, location, and abdominal wall thickness, contrast-enhanced sonography after contrast-enhanced CT is useful for confirmative diagnosis of small recurrent hepatocellular carcinoma with an atypical enhancement pattern on contrast-enhanced CT, even for lesions measuring 1 cm or smaller in diameter.