1. Department of Radiology, Inha University School of Medicine, Incheon 400-711, Korea.
2. Department of Radiology, Seoul National University College of Medicine, Seoul 110-744, Korea.
3. Department of Radiology, Boramae Medical Center, Seoul 156-707, Korea.
4. Department of Otolaryngology-Head & Neck Surgery, Inha University School of Medicine, Incheon 400-711, Korea.
5. Department of Radiology, Inha University Hospital, Incheon 400-711, Korea.