1. Department of Radiology, Seoul Metropolitan Government-Seoul National University Boramae Medical Center, Seoul, Korea.
2. Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
3. Department of Radiology, Pusan National University Yangsan Hospital, Pusan National University School of Medicine, Yangsan, Korea.
4. Department of Radiology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.