1. Department of Radiology, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Republic of Korea.
2. Department of Radiology and Institute of Radiation Medicine, Seoul National University College of Medicine, 101 Daehang-no, Chongno-gu, Seoul 110-744, Republic of Korea.
3. Department of Radiology, Soonchunhyang Bucheon University Hospital, Bucheon, Republic of Korea.
4. Department of Radiology and Cancer Research Institute, Seoul National University College of Medicine, Seoul, Republic of Korea.
5. Department of Radiology, Seoul St. Mary's Hospital, Catholic University of Korea, Seoul, Republic of Korea.