1. Department of Radiology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
2. Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
3. Department of Radiology, Inje University Busan Paik Hospital, Busan, Korea.
4. Department of Radiology, Seoul National University Hospital, Seoul, Korea.
5. Department of Radiology, Severance Hospital, Research Institute of Radiological Science Yonsei College of Medicine, Seoul, Korea.