1. From the Department of Medical Ultrasonics, Division of Interventional Ultrasound, Institute of Diagnostic and Interventional Ultrasound (B.X.L., G.L.H., X.H.X., B.W.Z., X.Y.X., M.D.L.), and Department of Liver Surgery (M.D.L.), the First Affiliated Hospital, Sun Yat-Sen University, 58 Zhong Shan Road 2, Guangzhou 510080, China.