title: Helical computed tomography scanning of the larynx and upper trachea in rabbits.
abstract: BACKGROUND
  Computed tomography (CT) is used to evaluate the human tracheobronchial tree because of its unsurpassed ability to visualize the airway and surrounding structures. To establish an ideal animal model for studying subglottic stenosis, we assessed the size and morphology of the normal rabbit's laryngotracheal airway by helical CT. We measured luminal dimensions at the levels of the arytenoid and cricoid cartilages and the first, third, and eighth tracheal rings. At all levels, the axial slices were used to calculate the maximum anteroposterior (AP) dimension, transverse dimension, and cross-sectional areas. We measured the tracheal length from the cricoid to the third and eighth tracheal rings on sagittal reformation. We assessed the hyoid, thyroid, cricoid, arytenoid, and tracheal rings for the presence of calcific or soft tissue densities. We also addressed the presence or absence of pre-epiglottic and paraglottic fat.
  
  
  RESULTS
  The mean AP tracheal dimension ± standard deviation (SD) was 8.6 ± 0.5 mm at the arytenoid level, 8.2 ± 0.7 mm at the cricoid level, and 7.7 ± 0.2 mm at the first tracheal ring level. The transverse tracheal dimension ±SD was 5.3 ± 0.1 mm at the arytenoid level, 5.5 ± 0.5 mm at the cricoid level, and 6.1 ± 0.6 mm at the first tracheal ring level. The mean tracheal area ±SD was 35.7 ± 2.2 mm(2) at the arytenoid level, 35.8 ± 5.1 mm(2) at the cricoid level, and 39.2 ± 4.3 mm(2) at the first tracheal ring level. The tracheal length ±SD was 10.7 ± 2.3 mm from the cricoid to the third tracheal ring and 19.1 ± 1.14 mm to the eighth tracheal ring. There was complete calcification of the hyoid in all rabbits. Only two rabbits showed complete thyroid, arytenoid, or tracheal ring calcification. The remaining airway components were otherwise either uncalcified or partially calcified. The uvula, epiglottis, aryepiglottic fold, vallecula, piriform sinus, true/false vocal cords, and pre-epiglottic/paraglottic fat were not seen in any rabbit.
  
  
  CONCLUSIONS
  Helical CT investigation provides good, highly definitive anatomic details of the larynx and trachea in rabbits. Such results may be used in further evaluation of the normal airway and in cases of subglottic stenosis.
authors.affiliation: Radiology Department, King Abdulaziz University Hospital, King Abdulaziz University, Jeddah, Western Region, Saudi Arabia. amrajlan@yahoo.com.
authors.forename: Amr M
authors.initials: AM
authors.lastname: Ajlan
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia. talkhatib@gmail.com.
authors.forename: Talal
authors.initials: T
authors.lastname: Al-Khatib
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia. mariamalsheikah@gmail.com.
authors.forename: Mariam
authors.initials: M
authors.lastname: Al-Sheikah
authors.affiliation: Department of Diagnostic Radiology, Faculty of Applied Medical Science, King Abdulaziz University, Jeddah, Saudi Arabia. sjastaniah@kau.edu.sa.
authors.forename: Saddig
authors.initials: S
authors.lastname: Jastaniah
authors.affiliation: Department of Diagnostic Radiology, Faculty of Applied Medical Science, King Abdulaziz University, Jeddah, Saudi Arabia. alaminsalihk@yahoo.com.
authors.forename: Alamin
authors.initials: A
authors.lastname: Salih
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia. dr_amt@live.com.
authors.forename: Abdulrahman
authors.initials: A
authors.lastname: Althubaiti
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia. abdulrah556@hotmail.com.
authors.forename: Abdulrahman
authors.initials: A
authors.lastname: Aljohani
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia. hanimarzouki@gmail.com.
authors.forename: Hani
authors.initials: H
authors.lastname: Marzouki
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Umm Al-Qura University, Mecca, Saudi Arabia. herabi@hotmail.com.
authors.forename: Ameen
authors.initials: A
authors.lastname: Alherabi
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Umm Al-Qura University, Mecca, Saudi Arabia. marglani1@yahoo.com.
authors.forename: Osama
authors.initials: O
authors.lastname: Marglani
authors.affiliation: Department of Biology, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia. sarmara@yahoo.com.
authors.forename: Samar
authors.initials: S
authors.lastname: Rabah
authors.affiliation: Experimental Surgery Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, 21589, Saudi Arabia. drgamalkarrouf@yahoo.com.|Department of Surgery, Anesthesiology and Radiology, Faculty of Veterinary Medicine, Mansoura University, Mansoura, 35516, Egypt. drgamalkarrouf@yahoo.com.
authors.forename: Gamal
authors.initials: G
authors.lastname: Karrouf
mesh_terms: D000818:Animals; D007830:Larynx / Q000000981:diagnostic imaging*; D008297:Male; D011817:Rabbits / Q000033:anatomy & histology*; D036542:Tomography, Spiral Computed / Q000662:veterinary*; D014132:Trachea / Q000000981:diagnostic imaging*