1. Department of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul 120-752, Korea.
2. Department of Biostatistics, Yonsei University College of Medicine, Seoul 102-752, Korea.
3. Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 138-736, Korea.
4. Department of Radiology, Haeundae Healings Hospital, Busan 612-851, Korea.
5. Department of Radiology, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul 143-729, Korea.
6. Department of Radiology, Kangbuk Samsung Hospital, Sungkyunkwan University, Seoul 143-729, Korea.
7. Department of Radiology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul 137-710, Korea.
8. Department of Radiology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul 135-720, Korea.
9. Department of Radiology, Seoul National University Hospital, Seoul 110-744, Korea.
10. Department of Radiology, Thyroid Center, Daerim St. Mary's Hospital, Seoul 150-822, Korea.
11. Department of Radiology, Dong-A University Medical Center, Busan 602-715, Korea.
12. Department of Radiology, Hanyang University Hospital, Hanyang University College of Medicine, Seoul 133-791, Korea.
13. Department of Radiology, Haeundae Paik Hospital, Inje University College of Medicine, Busan 612-862, Korea.
14. Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 135-710, Korea.
15. Department of Radiology, Human Medical Imaging and Intervention Center, Seoul 137-902, Korea.