1. From the Departments of Vascular and Interventional Radiology (F.G.I., K.H.T., W.H.Y., H.H.W., A.G., A.P., C.W.T., S.X.J.M.C., R.H.G.L., L.H.W.T., B.S.T.), Vascular Surgery (S.P.C.), and Renal Medicine (H.L.C.), Block 2 Level 1, Singapore General Hospital, Outram Rd, Singapore 169608; and Department of Radiology, Mount Elizabeth Hospital, Singapore (T.K.B.T.).