title: Dynamic airway evaluation with volume CT: initial experience.
abstract: OBJECTIVE
  The purpose of the study was to prospectively establish the use of a novel multidetector computed tomography unit (MDCT) with 320 x 0.5 detector rows for the evaluation of tracheomalacia by using a dynamic expiratory low-dose technique.
  
  
  METHODS
  Six adult patients (5 men, 1 woman; mean age, 53.7 years [37-70 years]) referred for a clinical suspicion of tracheomalacia were studied on a 320-row MDCT unit by using the following parameters: 120 kVp, 40-50 mA, 0.5-second gantry rotation, and z-axis coverage of 160 mm sufficient to cover the thoracic trachea to the proximal bronchi. Image acquisition occurred during a forceful exhalation. The image data set was subject to the following analyses: cross-sectional area of airway lumen at 4 predefined locations (thoracic inlet, aortic arch, carina, and bronchus intermedius) and measurement of airway volume.
  
  
  RESULTS
  All 6 patients had evidence of tracheomalacia, the proximal trachea collapsed at a later phase of expiration (3-4 seconds) than the distal trachea (2-3 seconds). The most common region of airway collapse occurred at the level of the aortic arch (5/6 [83%]), Three patients (50%) had diffuse segmental luminal narrowing that involved the tracheobronchial tree. The radiation dose (estimated dose length product, computed tomography console) measured 293.9 mGy in 1 subject and 483.5 mGy in 5 patients.
  
  
  CONCLUSIONS
  Four-dimensional true isophasic and isovolumetric imaging of the central airways by using 320-row MDCT is a viable technique for the diagnosis of tracheomalacia; it provides a comprehensive assessment of airways dynamic.
authors.affiliation: Department of Medical Imaging, University Health Network, Toronto General Hospital, Toronto, Ontario, Canada. Ute.Wagnetz@uhn.on.ca
authors.forename: Ute
authors.initials: U
authors.lastname: Wagnetz
authors.forename: Heidi C
authors.initials: HC
authors.lastname: Roberts
authors.forename: Taebong
authors.initials: T
authors.lastname: Chung
authors.forename: Demetris
authors.initials: D
authors.lastname: Patsios
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Chapman
authors.forename: Narinder S
authors.initials: NS
authors.lastname: Paul
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011857:Radiographic Image Interpretation, Computer-Assisted; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055090:Tracheomalacia / Q000000981:diagnostic imaging* / Q000503:physiopathology