1. From the Department of Interventional Radiology, St George’s University Hospitals NHS Foundation Trust and Medical School, Blackshaw Road, London SW17 0QT, England (U.P., R.D.); Centre for Medical Imaging, University College London, London, England (S.K.); Department of Vascular Surgery, Guy’s and St Thomas’ Hospital, London, England (O.W.J.); and Department of Radiology, Royal Sussex County Hospital, Brighton, England (J.H.J.).