Airway wall attenuation: a biomarker of airway disease in subjects with COPD

• Published in: Journal of applied physiology (1985) Vol. 107; no. 1; pp. 185 - 191
• Main Authors: Washko, George R, Dransfield, Mark T, Estepar, Raul San Jose, Diaz, Alejandro, Matsuoka, Shin, Yamashiro, Tsuneo, Hatabu, Hiroto, Silverman, Edwin K, Bailey, William C, Reilly, John J
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01.07.2009; American Physiological Society
• Subjects: Aged; Airway management; Biological and medical sciences; Biomarkers; Chronic obstructive pulmonary disease; Computed tomography; Female; Fundamental and applied biological sciences. Psychology; Humans; Lung - diagnostic imaging; Lung - pathology; Lungs; Male; Middle Aged; Phantoms, Imaging; Pulmonary Disease, Chronic Obstructive - diagnosis; Pulmonary Disease, Chronic Obstructive - diagnostic imaging; Pulmonary Disease, Chronic Obstructive - physiopathology; Respiratory function; Respiratory Function Tests; Software; Tomography; Tomography, X-Ray Computed - instrumentation; Tomography, X-Ray Computed - methods; Human; computed tomography; Lung disease; Wall; Respiratory disease; Biological marker; Respiratory system; Respiratory tract; Vertebrata; Mammalia; contrast reduction; Tomography; Bronchus disease; Chronic obstructive pulmonary disease
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.00216.2009

1 Pulmonary and Critical Care Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; 2 University of Alabama at Birmingham, Birmingham, Alabama; 3 Surgical Planning Laboratory, Laboratory of Mathematics in Imaging, Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts; 4 Department of Respiratory Diseases, Pontificia Universidad Catolica de Chile, Santiago, Chile; 5 Channing Laboratory, Boston, Massachusetts; and 6 Center for Pulmonary Functional Imaging, Brigham and Women's Hospital, Boston, Massachusetts Submitted 26 February 2009 ; accepted in final form 25 April 2009 The computed tomographic (CT) densities of imaged structures are a function of the CT scanning protocol, the structure size, and the structure density. For objects that are of a dimension similar to the scanner point spread function, CT will underestimate true structure density. Prior investigation suggests that this process, termed contrast reduction, could be used to estimate the strength of thin structures, such as cortical bone. In this investigation, we endeavored to exploit this process to provide a CT-based measure of airway disease that can assess changes in airway wall thickening and density that may be associated with the mural remodeling process in subjects with chronic obstructive pulmonary disease (COPD). An initial computer-based study using a range of simulated airway wall sizes and densities suggested that CT measures of airway wall attenuation could detect changes in both wall thickness and structure density. A second phantom-based study was performed using a series of polycarbonate tubes of known density. The results of this again demonstrated the process of contrast reduction and further validated the computer-based simulation. Finally, measures of airway wall attenuation, wall thickness, and wall area (WA) divided by total cross-sectional area, WA percent (WA%), were performed in a cohort of 224 subjects with COPD and correlated with spirometric measures of lung function. The results of this analysis demonstrated that wall attenuation is comparable to WA% in predicting lung function on univariate correlation and remain as a statistically significant correlate to the percent forced expiratory volume in 1 s predicted when adjusted for measures of both emphysema and WA%. These latter findings suggest that the quantitative assessment of airway wall attenuation may offer complementary information to WA% in characterizing airway disease in subjects with COPD. computed tomography; contrast reduction Address for reprint requests and other correspondence: G. R. Washko, Pulmonary and Critical Care Division, Dept. of Medicine, Brigham and Women's Hospital, 75 Francis St., Boston, MA 02115 (e-mail: Gwashko{at}Partners.org )