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


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.


CONCLUSIONS
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.
Department of Diagnostic Radiology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan. inomasa@mac.com
Masanori
M
Inoue
Ichiro
I
Hasegawa
Keiko
K
Nakano
Kazuhiro
K
Yamaguchi
Sachio
S
Kuribayashi
D000368:Aged; D005260:Female; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008297:Male; D011656:Pulmonary Emphysema / Q000150:complications* / Q000000981:diagnostic imaging; D011829:Radiation Dosage; D012129:Respiratory Function Tests; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed; D055089:Tracheobronchomalacia / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000209:etiology*