1. Department of Oral and Maxillofacial Radiology, Tohoku University Hospital, Sendai, Japan.
2. Department of Dental Informatics and Radiology, Tohoku University Graduate School of Dentistry, Sendai, Japan.
3. Department of Oral and Maxillofacial Surgery, Tohoku University Graduate School of Dentistry, Sendai, Japan.
4. Department of Diagnostic Radiology, Tohoku University Hospital, Sendai, Japan.