1. Department of Radiology, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Korea
2. Department of Radiology, Korea University Anam Hospital, Korea University College of Medicine, Seoul, Korea
3. Department of Radiology, Korea University Ansan Hospital, Korea University College of Medicine, Seoul, Korea
4. Department of Radiology, Nowon Eulji Medical Center, Eulji University College of Medicine, Seoul, Korea