1. Department of Radiology, Seoul National University Hospital, Seoul 03080, Korea.
2. Department of Radiology, Seoul National University College of Medicine, Seoul 03080, Korea.
3. Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul 03087, Korea.
4. Siemens Healthcare, Forchheim 91301, Germany.
5. Department of Radiology, SMG-SNU Boramae Medical Center, Seoul 07061, Korea.
6. Department of Radiology, KonKuk University Medical Center, Seoul 05030, Korea.
7. Department of Radiology, Chung-Ang University Hospital, Seoul 06973, Korea.