1. From the Department of Radiology, University of British Columbia, Royal Columbian Hospital, 300 Columbia St E, New Westminster, BC, Canada V3L 3W7 (J.I.B.); Department of Radiology and Imaging Sciences, University of Utah School of Medicine, Salt Lake City, Utah (B.Y.C.); and Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, Wis (P.M., K.S.L.).