1. Department of Radiology, Seoul National University College of Medicine, and Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul 03080, Korea.
2. Department of Radiology, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul 05030, Korea.
3. Department of Radiology, Institute of Medical Science, Research Institute of Clinical Medicine, Chonbuk National University Medical School and Hospital, Jeonju 54907, Korea.
4. Cancer Research Institute, Seoul National University College of Medicine, Seoul 03080, Korea.