Distribution of emphysema in heavy smokers: Impact on pulmonary function
Received 4 May 2009; accepted 5 August 2009. published online 07 September 2009.
Summary
Purpose
To investigate impact of distribution of computed tomography (CT) emphysema on severity of airflow limitation and gas exchange impairment in current and former heavy smokers participating in a lung cancer screening trial.
Materials and Methods
In total 875 current and former heavy smokers underwent baseline low-dose CT (30mAs) in our center and spirometry and diffusion capacity testing on the same day as part of the Dutch–Belgian Lung Cancer Screening Trial (NELSON). Emphysema was quantified for 872 subjects as the number of voxels with an apparent lowered X-ray attenuation coefficient. Voxels attenuated <−950HU were categorized as representing severe emphysema (ES950), while voxels attenuated between −910HU and −950HU represented moderate emphysema (ES910). Impact of distribution on severity of pulmonary function impairment was investigated with logistic regression, adjusted for total amount of emphysema.
Results
For ES910 an apical distribution was associated with more airflow obstruction and gas exchange impairment than a basal distribution (both p<0.01). The FEV1/FVC ratio was 1.6% (95% CI 0.42% to 2.8%) lower for apical predominance than for basal predominance, for Tlco/VA the difference was 0.12% (95% CI 0.076–0.15%). Distribution of ES950 had no impact on FEV1/FVC ratio, while an apical distribution was associated with a 0.076% (95% CI 0.038–0.11%) lower Tlco/VA (p<0.001).
Conclusion
In a heavy smoking population, an apical distribution is associated with more severe gas exchange impairment than a basal distribution; for moderate emphysema it is also associated with a lower FEV1/FVC ratio. However, differences are small, and likely clinically irrelevant.
aDepartment of Radiology, University Medical Center, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
bDepartment of Radiology, Meander Medical Center, Utrechtseweg 160, 3818 ES Amersfoort, The Netherlands
cDepartment of Pulmonology, St Anthonius Hospital, Koekoekslaan 1, 3435 CM Nieuwegein, The Netherlands
dDepartment of Pulmonology, University Medical Center, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
eImage Sciences Institute, University Medical Center, Lundlaan 6, 3584 EA Utrecht, The Netherlands
fDepartment of Pulmonology, Erasmus Medical Center, ‘s-Gravendijkwal 23, 03015 CE Rotterdam, The Netherlands
Corresponding author. Department of Radiology, University Medical Center, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands. Tel.: +31 302506687; fax: +31 302581098.
ABSTRACT