title: Frequency and severity of air trapping at dynamic expiratory CT in patients with tracheobronchomalacia.
abstract: OBJECTIVE
  The purpose of this study was to compare the frequency and severity of air trapping in patients with and without tracheobronchomalacia using dynamic expiratory volumetric CT.
  
  
  METHODS
  The study group consisted of 20 subjects, including 10 patients with bronchoscopically proven tracheobronchomalacia and 10 control subjects of similar ages without tracheobronchomalacia. All 20 subjects underwent MDCT performed at the end of deep inspiration and during dynamic expiration. The images were analyzed at three lung levels, and the extent of air trapping was assessed visually using a 5-point scale. For each subject, a total air-trapping score was derived by summing the values for the three lung levels (possible range, 0-12). Statistical analysis was performed using the Mann-Whitney U test.
  
  
  RESULTS
  In the tracheobronchomalacia group, 10 (100%) of 10 patients showed air trapping, with a median score of 5 (range, 2-12). In the control group, six (60%) of 10 subjects showed air trapping, with a median score of 2 (range, 0-3). The median total air-trapping score was significantly higher (p < 0.001) for the tracheobronchomalacia group compared with the control group. Excessive central airway collapse (expiratory reduction in cross-sectional area of > 50%) was seen on CT scans in all tracheobronchomalacia patients but in none of the control subjects.
  
  
  CONCLUSIONS
  Air trapping was observed with a higher frequency and greater severity in patients with tracheobronchomalacia than in a control group of patients of similar ages without tracheobronchomalacia.
authors.affiliation: Department of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Ave., Boston, MA 02215, USA.
authors.forename: J
authors.initials: J
authors.lastname: Zhang
authors.forename: I
authors.initials: I
authors.lastname: Hasegawa
authors.forename: H
authors.initials: H
authors.lastname: Hatabu
authors.forename: D
authors.initials: D
authors.lastname: Feller-Kopman
authors.forename: P M
authors.initials: PM
authors.lastname: Boiselle
mesh_terms: D000328:Adult; D000368:Aged; D000402:Airway Obstruction / Q000000981:diagnostic imaging* / Q000209:etiology*; D001982:Bronchial Diseases / Q000150:complications / Q000000981:diagnostic imaging*; D045853:Exhalation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012115:Residual Volume; D012189:Retrospective Studies; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed; D014133:Tracheal Diseases / Q000150:complications / Q000000981:diagnostic imaging*