1. Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea.
2. Department of Radiology, Hanyang University Hospital, Hanyang University College of Medicine, Seoul 04763, Korea.
3. Departments of Otorhinolaryngology-Head and Neck Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea.