1. From the Department of Medical Ultrasonics, Institute for Diagnostic and Interventional Ultrasound (L.Y.Z., S.L.C., Y.H., X.Y.X.), Department of Pediatric Surgery (H.D.C.), and Department of Anesthesiology (Y.X.Q.), the First Affiliated Hospital, Sun Yat-Sen University, 58 Zhongshan Rd 2, Guangzhou 510080, P.R. China; and Department of Pediatric Surgery, Guangzhou Women and Children’s Medical Center, Guangzhou, P.R. China (W.Z.).