1. From the Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Straße 62, 50937 Cologne, Germany (S.L.); Oregon Health and Science University Hospital Dotter Interventional Institute, Portland, OR (P.L.); and the Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114 (N.C., S.I.L.).