Open Access Research

Low-dose CT measurements of airway dimensions and emphysema associated with airflow limitation in heavy smokers: a cross sectional study

Akkelies E Dijkstra1*, Dirkje S Postma1, Nick ten Hacken1, Judith M Vonk12, Matthijs Oudkerk3, Peter MA van Ooijen3, Pieter Zanen4, Firdaus A Mohamed Hoesein4, Bram van Ginneken5, Michael Schmidt6 and Harry JM Groen1

Author Affiliations

1 University of Groningen, Department of Pulmonary Diseases, University Medical Center Groningen, GRIAC research institute, Groningen, the Netherlands

2 University of Groningen, Department of Epidemiology, University Medical Center Groningen, Groningen, the Netherlands

3 University of Groningen, Department of Radiology, University Medical Center Groningen, Groningen, the Netherlands

4 Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, the Netherlands

5 Department of Radiology, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands

6 Fraunhofer MEVIS, Institute for Medical Image Computing, Bremen, Germany

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Respiratory Research 2013, 14:11  doi:10.1186/1465-9921-14-11

Published: 28 January 2013

Abstract

Background

Increased airway wall thickness (AWT) and parenchymal lung destruction both contribute to airflow limitation. Advances in computed tomography (CT) post-processing imaging allow to quantify these features. The aim of this Dutch population study is to assess the relationships between AWT, lung function, emphysema and respiratory symptoms.

Methods

AWT and emphysema were assessed by low-dose CT in 500 male heavy smokers, randomly selected from a lung cancer screening population. AWT was measured in each lung lobe in cross-sectionally reformatted images with an automated imaging program at locations with an internal diameter of 3.5 mm, and validated in smaller cohorts of patients. The 15th percentile method (Perc15) was used to assess the severity of emphysema. Information about respiratory symptoms and smoking behavior was collected by questionnaires and lung function by spirometry.

Results

Median AWT in airways with an internal diameter of 3.5 mm (AWT3.5) was 0.57 (0.44 - 0.74) mm. Median AWT in subjects without symptoms was 0.52 (0.41-0.66) and in those with dyspnea and/or wheezing 0.65 (0.52-0.81) mm (p<0.001). In the multivariate analysis only AWT3.5 and emphysema independently explained 31.1%and 9.5%of the variance in FEV1%predicted, respectively, after adjustment for smoking behavior.

Conclusions

Post processing standardization of airway wall measurements provides a reliable and useful method to assess airway wall thickness. Increased airway wall thickness contributes more to airflow limitation than emphysema in a smoking male population even after adjustment for smoking behavior.

Keywords:
Airway dimensions; Low-dose CT; Respiratory symptoms; Smoking; Airflow limitation; Emphysema