1. Department of Otolaryngology-Head and Neck Surgery, Gachon University Gil Medical Center, Incheon 21565, Korea.
2. Department of Radiology, Gachon University Gil Medical Center, Incheon 21565, Korea.
3. Division of Pulmonology and Allergy, Department of Internal Medicine, Gachon University Gil Medical Center, Incheon 21565, Korea.