title: Reproducibility of forced expiratory tracheal collapse: assessment with MDCT in healthy volunteers.
abstract: OBJECTIVE
  To assess the reproducibility of multidetector-row computed tomography (MDCT)-measured forced expiratory tracheal collapse in healthy volunteers.
  
  
  METHODS
  Fourteen healthy, nonsmoking volunteers (6 males, 8 females, mean age 48.7 +/- 13.8 years) underwent repeat imaging 1 year after baseline imaging of tracheal dynamics employing the same scanner and technique (64-MDCT, 40 mAs, 120 kVp, and 0.625 mm detector collimation) with spirometric monitoring of total lung capacity and forced exhalation. Cross-sectional area (CSA) of the trachea was measured 1 cm above the aortic arch at end-inspiration and dynamic expiration, and percentage (%) expiratory reduction in tracheal lumen was calculated. Measurements were compared between baseline (Yr1) and repeat imaging (Yr2) using correlation coefficients and Bland-Altman plots.
  
  
  RESULTS
  Mean end-inspiratory CSA was 255.3 +/- 56 mm(2) at Yr1 and 255.1 +/- 52 mm(2) at Yr2; mean dynamic expiratory CSA was 125.6 +/- 60 mm(2) at Yr1 and 132.1 +/- 58 mm(2) at Yr2; and mean % expiratory reduction was 51.7 +/- 18% at Yr1 and 48.7 +/- 19% at Yr2. Mean differences between Yr1 and Yr2 values were 0.2 mm(2) for end-inspiratory CSA, 6.5 mm(2) for dynamic expiratory CSA, and 3.0% for percentage expiratory reduction. There was excellent correlation between the Yr1 and Yr2 measures of end-inspiratory CSA (r(2) = 0.97, P < .001), dynamic expiratory CSA (r(2) = 0.89, P < .001), and % expiratory reduction (r(2) = 0.86, P < .001).
  
  
  CONCLUSIONS
  MDCT measurements of forced expiratory tracheal collapse in healthy volunteers are highly reproducible over time.
authors.affiliation: Center for Airway Imaging and the Department of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA. pboisell@caregroup.harvard.edu
authors.forename: Phillip M
authors.initials: PM
authors.lastname: Boiselle
authors.forename: Carl R
authors.initials: CR
authors.lastname: O'Donnell
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Loring
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Bankier
mesh_terms: D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014132:Trachea / Q000000981:diagnostic imaging* / Q000502:physiology*