1. Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
2. Department of Radiology, Pusan National University Yangsan Hospital, Yangsan, Korea.
3. Department of Radiology, Kangwon National University Hospital, Chuncheon, Korea.
4. Department of Pediatrics, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea.