1. From the Department of Imaging and Interventional Radiology, Prince of Wales Hospital, 30-32 Ngan Shing St, Shatin, New Territories, Hong Kong (S.W.Y.Y.); Depart ments of Radiology (S.H.Y.L., C.S.Y.L., H.Y.F.W.) and Pathology (W.M.T.), Queen Mary Hospital, Hong Kong.