1. From the Department of Radiology (J.M., K.A.P.R., A.Z., A.R.K.), Department of Biostatistics (C.F.), and Department of Vascular and Interventional Radiology (C.S.G.), Johns Hopkins University, 1800 Orleans St, Zayed 7203, Baltimore, MD 21231; and Department of Urology, University of Texas Health Sciences Center, San Antonio, TX (R.R.).