1. Department of Radiology, Chung-Ang University Hospital, Seoul, Korea.
2. Department of Radiology, Seoul National University Hospital, Seoul, Korea.
3. Department of Radiology, Konkuk University Medical Center, Seoul, Korea.
4. Department of Radiology, Soonchunhyang University Bucheon Hospital, Bucheon, Korea.
5. Department of Radiology, Korea University Guro Hospital, Seoul, Korea.
6. Department of Radiology, Asan Medical Center, Seoul, Korea.
7. Department of Radiology, Chonnam National University Hospital, Gwangju, Korea.