1. Department of Radiology, Konkuk University Medical Center, Seoul 05030, Korea.
2. Department of Radiology, Seoul National University Hospital, Seoul 03080, Korea.
3. Department of Pre-Dentistry, Gangneung-Wonju National University College of Dentistry, Gangneung 25457, Korea.
4. Department of Radiology, Chung-Ang University Hospital, Seoul 06973, Korea.