1. Department of Radiology, Seoul National University College of Medicine, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul 110-744, Korea.
2. Institute of Radiation Medicine, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, Korea.
3. Cancer Research Institute, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, Korea.
4. Department of Pathology, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, Korea.