1. From the Department of Radiology, Graduate School of Medicine (M.K., J.S., O.A.), and the Department of Radiology, Institute of Medical Science (A.K.), the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan; and the Department of Radiology, School of Medicine, International University of Health and Welfare, Chiba, Japan (M.A.).