1. Department of Radiology, Chungnam University Hospital, Daejeon, Korea.
2. Department of Radiology, Seoul St. Mary' Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
3. Department of Radiology, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Incheon, Korea.
4. Department of Radiology, Bucheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Bucheon, Korea.