1. Department of Radiology, Armed Forces Daejeon Hospital, Daejeon, Korea
2. Department of Radiology, Seoul National University Hospital, Seoul, Korea
3. Department of Radiology, Seoul National University College of Medicine, Seoul, Korea
4. Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul National University Hospital, Seoul, Korea
5. G&E Alphadom Medical Center, Seongnam, Korea