1. Department of Radiology, Soonchunhyang University Seoul Hospital, Seoul, Korea
2. Department of Radiology, Soonchunhyang University Gumi Hospital, Gumi, Korea
3. Department of Radiology, Soonchunhyang University Cheonan Hospital, Cheonan, Korea
4. Department of Radiology, Soonchunhyang University Bucheon Hospital, Bucheon, Korea