1. Division of Otolaryngology, Tohoku Medical and Pharmaceutical University, Sendai 981-8536, Japan
2. Division of Pathology, Tohoku Medical and Pharmaceutical University, Sendai 981-8536, Japan
3. Technical Services Division, Tohoku Medical and Pharmaceutical University, Sendai 981-8536, Japan
4. Division of Radiology, Tohoku Medical and Pharmaceutical University, Sendai 981-8536, Japan