title: CT in the evaluation of the upper airway in healthy subjects and in patients with obstructive sleep apnea syndrome.
abstract: OBJECTIVE
  To study if the caliber of the upper airway, measured by CT, allows us to distinguish patients with obstructive sleep apnea syndrome (OSAS) from healthy people.
  
  
  METHODS
  Sixteen OSAS patients (with an apnea-hypopnea index > 10) and 39 healthy volunteers were studied. Polysomnography and CT of the upper airways during awake periods were performed in both groups. We used third-generation equipment (Toshiba model TCT 600QT). The area of the nasopharynx, oropharynx, and hypopharynx (in inspiration and expiration), the uvula diameter, and retropharyngeal tissue were evaluated. The simultaneous identification of the variables that differentiate between control and OSAS groups was determined by a multivariate discriminant model.
  
  
  RESULTS
  The retropharyngeal tissue in OSAS men was greater than those of the control men (10.3+/-3.6 mm vs 6.4+/-2.7 mm; p < 0.01). The multivariate analysis was performed on the 29 men (14 OSAS and 15 non-OSAS) who had information compiled in the selected parameters. The retropharyngeal tissue, expiratory hypopharynx, and uvular diameter are used to create a discriminant model (Wilks' lambda=0.556; p < 0.01). Two non-OSAS and five OSAS patients were incorrectly classified by this model as members of the other group (total rate of error, 24.14%). Therefore, the point estimates of specificity and sensitivity are 86.67% and 64.29%, respectively, for this model. The Pearson correlation coefficient between body mass index and retropharyngeal tissue is 0.63 (p < 0.001).
  
  
  CONCLUSIONS
  CT could play an important role in studying the upper airway in patients with OSAS. The determination of the retropharyngeal tissue by CT could be a useful procedure to evaluate OSAS.
authors.affiliation: Department of Radiology, La Princesa Hospital, Autonoma and Complutense Universities, Madrid, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Caballero
authors.forename: R
authors.initials: R
authors.lastname: Alvarez-Sala
authors.forename: F
authors.initials: F
authors.lastname: García-Río
authors.forename: C
authors.initials: C
authors.lastname: Prados
authors.forename: M A
authors.initials: MA
authors.lastname: Hernán
authors.forename: J
authors.initials: J
authors.lastname: Villamor
authors.forename: J L
authors.initials: JL
authors.lastname: Alvarez-Sala
mesh_terms: D000328:Adult; D000368:Aged; D000886:Anthropometry; D015992:Body Mass Index; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010614:Pharynx / Q000000981:diagnostic imaging* / Q000502:physiology; D017286:Polysomnography; D012119:Respiration / Q000502:physiology; D012189:Retrospective Studies; D012307:Risk Factors; D012680:Sensitivity and Specificity; D012727:Sex Characteristics; D012891:Sleep Apnea Syndromes / Q000000981:diagnostic imaging* / Q000503:physiopathology; D014057:Tomography, X-Ray Computed; D014609:Uvula / Q000000981:diagnostic imaging* / Q000502:physiology