Effect of inspiration on airway dimensions measured in maximal inspiration CT images of subjects without airflow limitation
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To study the effect of inspiration on airway dimensions measured in voluntary inspiration breath-hold examinations.
961 subjects with normal spirometry were selected from the Danish Lung Cancer Screening Trial. Subjects were examined annually for five years with low-dose CT. Automated software was utilized to segment lungs and airways, identify segmental bronchi, and match airway branches in all images of the same subject. Inspiration level was defined as segmented total lung volume (TLV) divided by predicted total lung capacity (pTLC). Mixed-effects models were used to predict relative change in lumen diameter (ALD) and wall thickness (AWT) in airways of generation 0 (trachea) to 7 and segmental bronchi (R1-R10 and L1-L10) from relative changes in inspiration level.
Relative changes in ALD were related to relative changes in TLV/pTLC, and this distensibility increased with generation (p < 0.001). Relative changes in AWT were inversely related to relative changes in TLV/pTLC in generation 3--7 (p < 0.001). Segmental bronchi were widely dispersed in terms of ALD (5.7 ± 0.7 mm), AWT (0.86 ± 0.07 mm), and distensibility (23.5 ± 7.7 %).
Subjects who inspire more deeply prior to imaging have larger ALD and smaller AWT. This effect is more pronounced in higher-generation airways. Therefore, adjustment of inspiration level is necessary to accurately assess airway dimensions.
• Airway lumen diameter increases and wall thickness decreases with inspiration
• The effect of inspiration is greater in higher-generation (more peripheral) airways
• Airways of generation 5 and beyond are as distensible as lung parenchyma
• Airway dimensions measured from CT should be adjusted for inspiration level
KeywordsComputed tomography Lung Airway Inspiration Obstructive disease
airway lumen diameter
airway wall thickness
wall thickness at an interior perimeter of 10 mm
forced expired volume in 1st second
forced vital capacity
total lung volume
predicted total lung capacity
chronic obstructive pulmonary disease
percentage of voxels in the lung with Hounsfield units below -910
percentage of voxels in the lung with Hounsfield units below -950
The scientific guarantor of this publication is Marleen de Bruijne. The authors of this manuscript declare relationships with the following companies: AstraZeneca, Sweden. This study has received funding by AstraZeneca, Sweden and the Netherlands Organisation for Scientific Research (NWO). One of the authors, Lars Lau Rakêt, has significant statistical expertise. Institutional Review Board approval was obtained. Written informed consent was obtained from all subjects (patients) in this study. Approval from the institutional animal care committee was not required, as the study did not involve animal subjects. No study subjects or cohorts have been previously reported. Methodology: retrospective, observational, performed at one institution.
- 6.Hasegawa M, Nasuhara Y, Onodera Y et al (2006) Airflow limitation and airway dimensions in chronic obstructive pulmonary disease. Am J Respir Crit Care Med 12:1309–1315Google Scholar
- 7.Brown RH, Scichilone N, Mudge B et al (2001) High-resolution computed tomographic evaluation of airway distensibility and the effects of lung inflation on airway caliber in healthy subjects and individuals with asthma. Am J Respir Crit Care Med 4:994–1001Google Scholar
- 8.Nakano Y, Wong JC, de Jong PA et al (2005) The prediction of small airway dimensions using computed tomography. Am J Respir Crit Care Med 2:142–146Google Scholar
- 9.Dijkstra AE, Postma DS, ten HN, et al (2013) Low-dose CT measurements of airway dimensions and emphysema associated with airflow limitation in heavy smokers: a cross sectional study. Respir Res :11Google Scholar
- 13.Brown RH, Herold C, Zerhouni EA, Mitzner W (1994) Spontaneous airways constrict during breath holding studied by high-resolution computed tomography. Chest 3:920–924Google Scholar
- 14.Scichilone N, Kapsali T, Permutt S, Togias A (2000) Deep inspiration-induced bronchoprotection is stronger than bronchodilation. Am J Respir Crit Care Med 3(Pt 1):910–916Google Scholar
- 15.Scichilone N, Permutt S, Togias A (2001) The lack of the bronchoprotective and not the bronchodilatory ability of deep inspiration is associated with airway hyperresponsiveness. Am J Respir Crit Care Med 2:413–419Google Scholar
- 16.Baldi S, Dellaca R, Govoni L et al (1985) (2010) Airway distensibility and volume recruitment with lung inflation in COPD. J Appl Physiol 4:1019–1026Google Scholar
- 22.Quanjer PH, Tammeling GJ, Cotes JE, et al (1993) Lung volumes and forced ventilatory flows. Report Working Party Standardization of Lung Function Tests, European Community for Steel and Coal. Official Statement of the European Respiratory Society. Eur Respir J Suppl :5-40Google Scholar
- 25.Lo P, Sporring J, Pedersen JJ, de Bruijne M (2009) Airway tree extraction with locally optimal paths. Med Image Comput Comput Assist Interv Pt 2:51–58Google Scholar
- 28.Feragen A, Petersen J, Owen M et al (2012) A hierarchical scheme for geodesic anatomical labeling of airway trees. Med Image Comput Comput Assist Interv Pt 3:147–155Google Scholar
- 30.Petersen J, Gorbunova V, Nielsen M, et al (2011) Longitudinal Analysis of Airways using Registration. The Fourth International Workshop on Pulmonary Image AnalysisGoogle Scholar
- 34.Petersen J, Gorbunova V, Nielsen M, et al (2011) Longitudinal Analysis of Airways using Registration. The Fourth International Workshop on Pulmonary Image AnalysisGoogle Scholar