Chronic obstructive pulmonary disease (COPD) is characterized by emphysematous destruction of lung parenchyma and airway remodeling which lead to limitation of airflow. Computed tomography is of considerable value in quantifying the severity of the disease in COPD either by visual or by quantitative CT techniques (QCT). This study was designed to assess the relationship between quantitative computed tomography parameters and spirometric measurements of disease severity in cases with COPD.
Materials and Methods: A total of 100 cases between age group 41 to 65 years, who were proved to have COPD by pulmonary function test were recruited. Inspiratory CT was designed to take a deep breath and plain CT chest was taken at full inspiration to obtain total lung capacity. Expiratory CT was asked to hold breath in normal expiration and CT chest was taken to obtain functional residual capacity. Inner and outer diameters and wall thick ness were measured manually and their average value was considered. Correlations analysis was conducted between spirometric measurements and QCT measures.
Results: The mean values of low attenuation areas in inspiration <-950HU was gradually increased from GOLD stage-I to GOLD stage-IV. Mean values of low attenuation areas in expiration <-856HU was gradually decreased from GOLD stage-I to GOLD stage-IV. Low attenuation areas in inspiration <-950HU showed correlation for both FEV1/FVC (-0.752) and FEV1 (-0.806) (p<0.005). Low attenuation areas in expiration <-856HU showed correlation for both FEV1/FVC (-0.786) and FEV1 (-0.928) (p<0.005).
Conclusion: In COPD cases, there is a strong association between spirometric measurements and QCT measurements of inspiratory and expiratory low attenuation areas.