1. Department of Radiology, Kangwon National University Hospital, College of Medicine, Kangwon National University, Chuncheon, Korea.
2. Department of Radiology, Korea University Ansan Hospital, Ansan, Korea.
3. Department of Radiology, Soonchunhyang University Cheonan Hospital, Cheonan, Korea.
4. Department of Radiology, Gangneung Asan Hospital, University of Ulsan College of Medicine, Gangneung, Korea.