Incidence of tracheobronchomalacia associated with pulmonary emphysema: detection with paired inspiratory-expiratory multidetector computed tomography using a low-dose technique

Jpn J Radiol. 2009 Oct;27(8):303-8. doi: 10.1007/s11604-009-0342-3. Epub 2009 Oct 27.


Purpose: The purpose of this study was to evaluate the frequency of tracheobronchomalacia (TBM) associated with pulmonary emphysema with paired inspiratory-expiratory multidetector computed tomography (MDCT) using a low-dose technique.

Materials and methods: This study included 56 consecutive patients (55 men, 1 woman; mean age 68.9 years) with pulmonary emphysema who had undergone paired inspiratory-expiratory CT scanning with a low-dose technique (40 mA). All images were retrospectively examined by two thoracic radiologists in a blinded fashion. The diagnosis of TBM was based on the standard criterion of >50% reduction in the cross-sectional area of the tracheobronchial lumen at the end-expiratory phase. A mild TBM criterion of >30% reduction was also reviewed. All patients underwent pulmonary function tests. The relation between the forced expiratory volume in 1 s (FEV(1.0%)) and TBM was statistically analyzed.

Results: Four (7.1%) and eight (14.3%) patients were diagnosed as TBM based on the standard and mild criteria, respectively. In four patients, the percentages of luminal narrowing were 63.4% and 51.2%, respectively for tracheomalacia and 59.2% and 62.0%, respectively, for bronchomalacia. The FEV(1.0%) values between patients with and without TBM showed no statistical difference.

Conclusion: The incidence of TBM associated with pulmonary emphysema was 7.1% with the standard criterion. It is possible that TBM has been underdiagnosed in a number of patients with pulmonary emphysema.

MeSH terms

  • Aged
  • Female
  • Humans
  • Incidence
  • Japan / epidemiology
  • Male
  • Pulmonary Emphysema / complications*
  • Pulmonary Emphysema / diagnostic imaging
  • Radiation Dosage
  • Respiratory Function Tests
  • Retrospective Studies
  • Statistics, Nonparametric
  • Tomography, X-Ray Computed
  • Tracheobronchomalacia / diagnostic imaging
  • Tracheobronchomalacia / epidemiology*
  • Tracheobronchomalacia / etiology*