1. From the Department of Radiology, University of California–Los Angeles, David Geffen School of Medicine at UCLA, Los Angeles, Calif (N.J., S.Y.); College of Electrical and Computer Engineering, National Chiao Tung University, HsinChu Taiwan (S.Y.); Department of Biomathematics, University of California–Los Angeles, Los Angeles, Calif (J.G.); and Department of Diagnostic Radiology, University of Hong Kong, Room 406, Block K, Queen Mary Hospital, 102 Pok Fu Lam Rd, Hong Kong (M.D.K.).