1. From the Departments of Radiology (C.C., K..F.K.F., C.W.K.N., P.K.J.C., K.C.W., E.Y.K.) and Paediatrics and Adolescent Medicine (K.S.G.L., A.C.), Hong Kong Children’s Hospital, 1 Shing Cheong Road, Kowloon Bay, Hong Kong; and Department of Paediatrics and Adolescent Medicine, The University of Hong Kong, Pok Fu Lam, Hong Kong (A.C.).