Accurate measurement of small airways on low-dose thoracic CT scans in smokers.

BACKGROUND Partial volume averaging and tilt relative to the scan plane on transverse images limit the accuracy of airway wall thickness measurements on CT scan, confounding assessment of the relationship between airway remodeling and clinical status in COPD. The purpose of this study was to assess the effect of partial volume averaging and tilt corrections on airway wall thickness measurement accuracy and on relationships between airway wall thickening and clinical status in COPD. METHODS Airway wall thickness measurements in 80 heavy smokers were obtained on transverse images from low-dose CT scan using the open-source program Airway Inspector. Measurements were corrected for partial volume averaging and tilt effects using an attenuation- and geometry-based algorithm and compared with functional status. RESULTS The algorithm reduced wall thickness measurements of smaller airways to a greater degree than larger airways, increasing the overall range. When restricted to analyses of airways with an inner diameter < 3.0 mm, for a theoretical airway of 2.0 mm inner diameter, the wall thickness decreased from 1.07 ± 0.07 to 0.29 ± 0.10 mm, and the square root of the wall area decreased from 3.34 ± 0.15 to 1.58 ± 0.29 mm, comparable to histologic measurement studies. Corrected measurements had higher correlation with FEV₁, differed more between BMI, airflow obstruction, dyspnea, and exercise capacity (BODE) index scores, and explained a greater proportion of FEV1 variability in multivariate models. CONCLUSIONS Correcting for partial volume averaging improves accuracy of airway wall thickness estimation, allowing direct measurement of the small airways to better define their role in COPD.

[1]  Susan Murray,et al.  Relationship between quantitative CT metrics and health status and BODE in chronic obstructive pulmonary disease , 2012, Thorax.

[2]  T. Betsuyaku,et al.  The role of matrix metalloproteinase-9 in cigarette smoke-induced emphysema. , 2011, American journal of respiratory and critical care medicine.

[3]  A. Gulsvik,et al.  Quantitative CT measures of emphysema and airway wall thickness are related to D(L)CO. , 2011, Respiratory medicine.

[4]  D. Lynch,et al.  The National Lung Screening Trial: overview and study design. , 2011, Radiology.

[5]  Wei Wang,et al.  Measuring small airways in transverse CT images correction for partial volume averaging and airway tilt. , 2010, Academic radiology.

[6]  Denise R. Aberle,et al.  Baseline Characteristics of Participants in the Randomized National Lung Screening Trial , 2010, Journal of the National Cancer Institute.

[7]  W. MacNee,et al.  Airway dimensions in COPD: relationships with clinical variables. , 2010, Respiratory medicine.

[8]  Raúl San José Estépar,et al.  Relationship of emphysema and airway disease assessed by CT to exercise capacity in COPD. , 2010, Respiratory medicine.

[9]  Raúl San José Estépar,et al.  Quantitative assessment of bronchial wall attenuation with thin-section CT: An indicator of airflow limitation in chronic obstructive pulmonary disease. , 2010, AJR. American journal of roentgenology.

[10]  G. Washko,et al.  Association of COPD candidate genes with computed tomography emphysema and airway phenotypes in severe COPD , 2010, European Respiratory Journal.

[11]  Raúl San José Estépar,et al.  Physiological and computed tomographic predictors of outcome from lung volume reduction surgery. , 2010, American journal of respiratory and critical care medicine.

[12]  Asger Dirksen,et al.  Quantitative computed tomography measures of emphysema and airway wall thickness are related to respiratory symptoms. , 2010, American journal of respiratory and critical care medicine.

[13]  Jason C Woods,et al.  Effects of CT section thickness and reconstruction kernel on emphysema quantification relationship to the magnitude of the CT emphysema index. , 2010, Academic radiology.

[14]  E. Silverman,et al.  Sex differences in emphysema and airway disease in smokers. , 2009, Chest.

[15]  P. Paré,et al.  Prediction of the rate of decline in FEV1 in smokers using quantitative computed tomography , 2009, Thorax.

[16]  Raúl San José Estépar,et al.  CT metrics of airway disease and emphysema in severe COPD. , 2009, Chest.

[17]  D. Sampson,et al.  Quantifying tracheobronchial tree dimensions: methods, limitations and emerging techniques , 2009, European Respiratory Journal.

[18]  A. Gulsvik,et al.  Quantitative computed tomography: emphysema and airway wall thickness by sex, age and smoking , 2009, European Respiratory Journal.

[19]  Yasutaka Nakano,et al.  Airway wall thickening and emphysema show independent familial aggregation in chronic obstructive pulmonary disease. , 2008, American journal of respiratory and critical care medicine.

[20]  Oliver Weinheimer,et al.  MDCT assessment of airway wall thickness in COPD patients using a new method: correlations with pulmonary function tests , 2008, European Radiology.

[21]  Stephen Lam,et al.  Airway wall thickness assessed using computed tomography and optical coherence tomography. , 2008, American journal of respiratory and critical care medicine.

[22]  Joon Beom Seo,et al.  Semi-Automatic Measurement of the Airway Dimension by Computed Tomography Using the Full-Width-Half-Maximum Method: a Study on the Measurement Accuracy according to the CT Parameters and Size of the Airway , 2008, Korean journal of radiology.

[23]  J. Seo,et al.  Semi-Automatic Measurement of the Airway Dimension by Computed Tomography Using the Full-With-Half-Maximum Method: a Study of the Measurement Accuracy according to the Orientation of an Artificial Airway , 2008, Korean journal of radiology.

[24]  Stephen Lam,et al.  The effects of radiation dose and CT manufacturer on measurements of lung densitometry. , 2007, Chest.

[25]  Talissa A Altes,et al.  Characterization of the relation between CT technical parameters and accuracy of quantification of lung attenuation on quantitative chest CT. , 2007, AJR. American journal of roentgenology.

[26]  John Yee,et al.  The association between small airway obstruction and emphysema phenotypes in COPD. , 2007, Chest.

[27]  P. Gevenois,et al.  Pulmonary emphysema: radiation dose and section thickness at multidetector CT quantification--comparison with macroscopic and microscopic morphometry. , 2007, Radiology.

[28]  Jin Hwan Kim,et al.  Comparison of standard- and low-radiation-dose CT for quantification of emphysema. , 2007, AJR. American journal of roentgenology.

[29]  Carl-Fredrik Westin,et al.  Accurate Airway Wall Estimation Using Phase Congruency , 2006, MICCAI.

[30]  M. Hasegawa,et al.  Airflow limitation and airway dimensions in chronic obstructive pulmonary disease. , 2006, American journal of respiratory and critical care medicine.

[31]  N L Müller,et al.  Computed tomographic imaging of the airways: relationship to structure and function , 2005, European Respiratory Journal.

[32]  F. Laurent,et al.  Airway wall thickness in cigarette smokers: quantitative thin-section CT assessment. , 2005, Radiology.

[33]  Gianna Camiciottoli,et al.  Chronic obstructive pulmonary disease: thin-section CT measurement of airway wall thickness and lung attenuation. , 2005, Radiology.

[34]  Jonathan G Goldin,et al.  Emphysema: effect of reconstruction algorithm on CT imaging measures. , 2004, Radiology.

[35]  P. Paré,et al.  The nature of small-airway obstruction in chronic obstructive pulmonary disease. , 2004, The New England journal of medicine.

[36]  Milan Sonka,et al.  Integrated system for CT-based assessment of parenchymal lung disease , 2002, Proceedings IEEE International Symposium on Biomedical Imaging.

[37]  P. Paré,et al.  Computed tomographic measurements of airway dimensions and emphysema in smokers. Correlation with lung function. , 2000, American journal of respiratory and critical care medicine.

[38]  G G King,et al.  Evaluation of airways in obstructive pulmonary disease using high-resolution computed tomography. , 1999, American journal of respiratory and critical care medicine.

[39]  W. Hop,et al.  Compliance, hysteresis, and collapsibility of human small airways. , 1999, American journal of respiratory and critical care medicine.

[40]  G J Kemerink,et al.  CT lung densitometry: dependence of CT number histograms on sample volume and consequences for scan protocol comparability. , 1997, Journal of computer assisted tomography.

[41]  M. Cosio,et al.  Morphometry of small airways in smokers and its relationship to emphysema type and hyperresponsiveness. , 1995, American journal of respiratory and critical care medicine.

[42]  T Takishima,et al.  Site of airway obstruction in pulmonary disease: direct measurement of intrabronchial pressure. , 1992, Journal of applied physiology.

[43]  M. Lebowitz,et al.  Changes in the normal maximal expiratory flow-volume curve with growth and aging. , 1983, The American review of respiratory disease.

[44]  J. Hogg,et al.  Site and nature of airway obstruction in chronic obstructive lung disease. , 1968, The New England journal of medicine.