1. Department of Radiology, Ansan Hospital, Korea University College of Medicine, Ansan, Korea.
2. Medical Science Research Center, Ansan Hospital, Korea University College of Medicine, Ansan, Korea.
3. Department of Radiology, National Cancer Center, Goyang, Korea.
4. Department of Radiology, Korea University Guro Hospital, College of Medicine Korea University, Seoul, Korea.
5. Department of Radiology, Anam Hospital, Korea University College of Medicine, Seoul, Korea.