title: Is Ultrasound a Valid and Reliable Imaging Modality for Airway Evaluation?: An Observational Computed Tomographic Validation Study Using Submandibular Scanning of the Mouth and Oropharynx.
abstract: OBJECTIVE
  Ultrasound (US) imaging of the airway may be useful in predicting difficulty of airway management (DAM); but its use is limited by lack of proof of its validity and reliability. We sought to validate US imaging of the airway by comparison to CT-scan, and to assess its inter- and intra-observer reliability. We used submandibular sonographic imaging of the mouth and oropharynx to examine how well the ratio of tongue thickness to oral cavity height correlates with the ratio of tongue volume to oral cavity volume, an established tomographic measure of DAM.
  
  
  METHODS
  A cohort of 34 patients undergoing CT-scan was recruited. Study standardized assessments included CT-measured ratios of tongue volume to oropharyngeal cavity volume; tongue thickness to oral cavity height; and US-measured ratio of tongue thickness to oral cavity height. Two sonographers independently performed US imaging of the airway before and after CT-scan.
  
  
  RESULTS
  Our findings indicate that the US-measured ratio of tongue thickness to oral cavity height highly correlates with the CT-measured ratio of tongue volume to oral cavity volume. US measurements also demonstrated strong inter- and intra-observer reliability.
  
  
  CONCLUSIONS
  This study suggests that US is a valid and reliable tool for imaging the oral and oropharyngeal parts of the airway, as well as for measuring the volumetric relationship between the tongue and oral cavity, and may therefore be a useful predictor of DAM.
authors.affiliation: Department of Anesthesia and the Li Ka Shing Knowledge Institute, St. Michael's Hospital, University of Toronto, Toronto, Canada.
authors.forename: Faraj W
authors.initials: FW
authors.lastname: Abdallah
authors.affiliation: Department of Radiology, Princess Margaret Hospital, University Health Network, University of Toronto, Toronto, Canada.
authors.forename: Eugene
authors.initials: E
authors.lastname: Yu
authors.affiliation: Department of Anesthesia, Chulalongkorn University, Thailand.
authors.forename: Phantila
authors.initials: P
authors.lastname: Cholvisudhi
authors.affiliation: Department of Anesthesia, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, Canada.
authors.forename: Ahtsham U
authors.initials: AU
authors.lastname: Niazi
authors.affiliation: Department of Anesthesia, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, Canada.
authors.forename: Ki J
authors.initials: KJ
authors.lastname: Chin
authors.affiliation: Department of Anesthesia, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, Canada.
authors.forename: Sherif
authors.initials: S
authors.lastname: Abbas
authors.affiliation: Department of Anesthesia, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, Canada.
authors.forename: Vincent W
authors.initials: VW
authors.lastname: Chan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008334:Mandible; D008875:Middle Aged; D009055:Mouth / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D015588:Observer Variation; D009960:Oropharynx / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed; D014059:Tongue / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D014463:Ultrasonography; D055815:Young Adult
keywords: difficult airway screening; sonographic imaging of the airway; submandibular ultrasound; tongue and oral cavity volume; ultrasound of the mouth and oropharynx