1. Department of Radiology and Medical Research Institute, School of Medicine, Ewha Womans University, Seoul 158-710, Korea.
2. Department of Radiology, College of Medicine, The Catholic University of Korea, Seoul St. Mary's Hospital, Seoul 137-040, Korea.
3. Department of Internal Medicine, Inje University College of Medicine, Ilsan Paik Hospital, Goyang 411-706, Korea.