title: Tracheobronchomalacia: comparison between end-expiratory and dynamic expiratory CT for evaluation of central airway collapse.
abstract: OBJECTIVE
  To compare dynamic expiratory and end-expiratory computed tomography (CT) for depicting central airway collapse in patients with acquired tracheobronchomalacia (TBM).
  
  
  METHODS
  Institutional review board approval was obtained, and informed consent was not needed. Retrospective review was performed of all patients with a CT diagnosis of TBM in a 10-month period (n = 34) who underwent evaluation of airway disease by means of three different sequences at multi-detector row CT: end inspiration, dynamic expiration, and end expiration (the latter was performed only at the levels of the aortic arch, carina, and bronchus intermedius). Fourteen patients (11 men, three women; age range, 19-79 years) who had comparable images obtained with all three sequences at any of these three levels were included in the study. The degree of airway collapse was measured by two thoracic radiologists in consensus by calculating the percentage change in the area of the airway between inspiratory and expiratory scanning. Statistical analysis was performed by using the paired t test.
  
  
  RESULTS
  Dynamic expiratory CT elicited a significantly greater degree of airway collapse than end-expiratory CT at all three levels (P < .005). The mean percentages of airway collapse at each of the three levels were as follows: aortic arch, 53.9% with dynamic expiration versus 35.7% with end expiration (P = .0046); carina, 53.6% with dynamic expiration versus 30.9% with end expiration (P < .0001); and bronchus intermedius, 57.5% with dynamic expiration versus 28.6% with end expiration (P = .0022).
  
  
  CONCLUSIONS
  Dynamic expiratory CT elicits a significantly greater degree of airway collapse than standard end-expiratory CT in patients with TBM.
authors.affiliation: Departments of Radiology, Pulmonary Medicine, and Anesthesia, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215, USA.
authors.forename: Ronaldo H
authors.initials: RH
authors.lastname: Baroni
authors.forename: David
authors.initials: D
authors.lastname: Feller-Kopman
authors.forename: Mizuki
authors.initials: M
authors.lastname: Nishino
authors.forename: Hiroto
authors.initials: H
authors.lastname: Hatabu
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Loring
authors.forename: Armin
authors.initials: A
authors.lastname: Ernst
authors.forename: Phillip M
authors.initials: PM
authors.lastname: Boiselle
mesh_terms: D000328:Adult; D000368:Aged; D000402:Airway Obstruction / Q000000981:diagnostic imaging* / Q000209:etiology; D001995:Bronchography; D002357:Cartilage Diseases / Q000000981:diagnostic imaging* / Q000209:etiology; D005260:Female; D006801:Humans; D001239:Inhalation / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D011857:Radiographic Image Interpretation, Computer-Assisted; D015656:Respiratory Mechanics / Q000502:physiology*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D036542:Tomography, Spiral Computed; D014132:Trachea / Q000000981:diagnostic imaging; D014133:Tracheal Diseases / Q000000981:diagnostic imaging* / Q000209:etiology