1. Department of Radiology and the Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
2. Department of Radiology and Thyroid Center, Daerim St. Mary's Hospital, Seoul, Korea.
3. Department of Radiology, Inje University Haeundae Paik Hospital, Inje University College of Medicine, Busan, Korea.
4. Department of Radiology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.