1 From the Department of Radiology, Stanford University School of Medicine, 453 Quarry Rd, 324-7, Palo Alto, CA 94304 (V.L.T.); Medical Research Institute of New Zealand, Wellington, New Zealand, and Artibiotics, Wellington, New Zealand (C.K.); Division of Vascular and Interventional Radiology, Department of Radiology, Montefiore Medical Center, Bronx, NY (K.W.); and Division of Interventional Radiology, Department of Radiology, NewYork-Presbyterian Weill Cornell Medicine, New York, NY (A.S.M.).