1. From the Institute of Diagnostic and Interventional Radiology (R.J.G., T.D., A.C.B., S.L., A.I.I., T.P., L.P., C.H.G., P.F., D.M., R.H., J.K.) and Institute of Medical Statistics and Bioinformatics (M.G.H.), Faculty of Medicine, University Hospital Cologne, University of Cologne, Kerpener Strasse 62, 50937 Cologne, Germany.