1. Department of Radiology, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, Korea.
2. Department of Radiology, Seoul National University Bundang Hospital, Seongnam, Korea.
3. Department of Internal Medicine, Incheon Medical Center, Incheon, Korea.
4. Department of Radiology, Seoul Medical Center, Seoul, Korea.
5. Department of Radiology, National Medical Center, Seoul, Korea.
6. Department of Radiology, Myongji Hospital, Goyang, Korea.
7. Department of Radiology, Chonnam National University Hospital, Gwangju, Korea.