Browsing by Author "Dransfield, Mark T."

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    Airway wall attenuation: a biomarker of airway disease in subjects with COPD
    (AMER PHYSIOLOGICAL SOC, 2009) 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.
    Washko GR, Dransfield MT, Estepar RS, Diaz A, Matsuoka S, Yamashiro T, Hatabu H, Silverman EK, Bailey WC, Reilly JJ. Airway wall attenuation: a biomarker of airway disease in subjects with COPD. J Appl Physiol 107: 185-191, 2009. First published April 30, 2009; doi:10.1152/japplphysiol.00216.2009.-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.
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    Effect of Emphysema on CT Scan Measures of Airway Dimensions in Smokers
    (2013) Díaz Fuenzalida, Alejandro; Han, Meilan K.; Come, Carolyn E.; Estepar, Raúl San José; Ross, James; Kim, Victor; Dransfield, Mark T.; Curran Everett, Douglas; Schroeder, Joyce D.; Lynch, David; Tschirren, Juerg; Silverman, Edwin K.; Washko, Geroge R.
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    Quantitative Assessment of Bronchial Wall Attenuation With Thin-Section CT: An Indicator of Airflow Limitation in Chronic Obstructive Pulmonary Disease
    (AMER ROENTGEN RAY SOC, 2010) Yamashiro, Tsuneo; Matsuoka, Shin; Estepar, Raul San Jose; Dransfield, Mark T.; Diaz, Alejandro; Reilly, John J.; Patz, Samuel; Murayama, Sadayuki; Silverman, Edwin K.; Hatabu, Hiroto; Washko, George R.
    OBJECTIVE. The purpose of this study was to evaluate the relation between bronchial wall attenuation on thin-section CT images and airflow limitation in persons with chronic obstructive pulmonary disease. SUBJECTS AND
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    Quantitative CT Measurement of Cross-sectional Area of Small Pulmonary Vessel in COPD: Correlations with Emphysema and Airflow Limitation
    (ELSEVIER SCIENCE INC, 2010) Matsuoka, Shin; Washko, George R.; Dransfield, Mark T.; Yamashiro, Tsuneo; Estepar, Raul San Jose; Diaz, Alejandro; Silverman, Edwin K.; Patz, Samuel; Hatabu, Hiroto
    Rationale and Objectives: Pulmonary vascular alteration is one of the characteristic features of chronic obstructive pulmonary disease (COPD). Recent studies suggest that vascular alteration is closely related to endothelial dysfunction and may be further influenced by emphysema. However, the relationship between morphological alteration of small pulmonary vessels and the extent of emphysema has not been assessed in vivo. The objectives of this study are: to evaluate the correlation of total cross-sectional area (CSA) of small pulmonary vessels with the extent of emphysema and airflow obstruction using CT scans and to assess the difference of total CSA between COPD phenotypes.