Low-dose CT measurements of airway dimensions and emphysema associated with airflow limitation in heavy smokers: a cross sectional study.
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.
University of Groningen, Department of Pulmonary Diseases, University Medical Center Groningen, GRIAC research institute, Groningen, the Netherlands. a.e.dijkstra@umcg.nl
Akkelies E
AE
Dijkstra
Dirkje S
DS
Postma
Nick
N
ten Hacken
Judith M
JM
Vonk
Matthijs
M
Oudkerk
Peter M A
PM
van Ooijen
Pieter
P
Zanen
Firdaus A
FA
Mohamed Hoesein
Bram
B
van Ginneken
Michael
M
Schmidt
Harry J M
HJ
Groen
D019412:Anatomy, Cross-Sectional; D003627:Data Interpretation, Statistical; D005541:Forced Expiratory Volume; D006801:Humans; D016014:Linear Models; D008168:Lung / Q000473:pathology; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged; D011656:Pulmonary Emphysema / Q000000981:diagnostic imaging* / Q000503:physiopathology; D012129:Respiratory Function Tests; D012137:Respiratory System / Q000000981:diagnostic imaging*; D012907:Smoking / Q000009:adverse effects*; D014057:Tomography, X-Ray Computed / Q000379:methods*