1. From the Departments of Radiology (R.W.v.H., P.A.d.J., M.J.W., T.L.) and Cardiology (M.V.), University Medical Center Utrecht, Utrecht University, PO Box 85500, 3508GA Utrecht, the Netherlands; Department of Radiology, Stanford University School of Medicine, Stanford, Calif (M.J.W.); and Image Sciences Institute, University Medical Center Utrecht, Utrecht, the Netherlands (I.I.).