title: Comparison of sonography and computed tomography as imaging tools for assessment of airway structures.
abstract: OBJECTIVE
  The aim of this study was to compare airway anatomic parameters as measured by sonography and computed tomography (CT).
  
  
  METHODS
  Fifteen adult patients underwent CT followed by sonography of the anterior neck under standard conditions. A radiologist and an anesthesiologist with experience in airway imaging examined the scans and performed measurements of specific airway parameters: distance to the posterior surface of the tongue, thickness of the submental region, hyomental distance, depth of the epiglottis from skin (above and below the hyoid bone), thyrohyoid distance, depth of the arytenoid cartilage from skin, and fat pad thickness at the thyroid cartilage. After performing the measurements, they compared the images by the two modalities for descriptions of the structures. Means and SDs were calculated for the measurements, and a paired t test was performed to determine statistically significant differences in the measurements by sonography and CT.
  
  
  RESULTS
  The means of all parameters were closely related except hyomental distance (sonography, 5.23 ± 0.58 cm; CT, 3.50 ± 0.42 cm). The paired t test showed that the mean values for depth of the epiglottis below the hyoid (3.89 versus 4.17 cm; P = .31), thyrohyoid distance (1.03 versus 1.02 cm; P = .95), and depth of the arytenoid cartilage (2.90 versus 2.66 cm; P = .21) were not significantly different as measured by sonography and CT, respectively.
  
  
  CONCLUSIONS
  The study shows that sonography can reliably image all of the structures visualized by CT, and in general, infrahyoid parameters agree well between the two modalities, as opposed to suprahyoid parameters, which may be affected by unintentional head extension.
authors.affiliation: Department of Anesthesia, University Health Network, Toronto Western Hospital, 399 Bathurst St, McL 2-405, Toronto, ON M5T 2S8, Canada. arun.prasad@uhn.on.ca
authors.forename: Arun
authors.initials: A
authors.lastname: Prasad
authors.forename: Eugene
authors.initials: E
authors.lastname: Yu
authors.forename: David T
authors.initials: DT
authors.lastname: Wong
authors.forename: Reena
authors.initials: R
authors.lastname: Karkhanis
authors.forename: Patrick
authors.initials: P
authors.lastname: Gullane
authors.forename: Vincent W S
authors.initials: VW
authors.lastname: Chan
mesh_terms: D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009333:Neck / Q000000981:diagnostic imaging*; D010865:Pilot Projects; D011446:Prospective Studies; D012016:Reference Values; D012137:Respiratory System / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014463:Ultrasonography