High-resolution computed tomography features in patients with chronic obstructive pulmonary disease

Introduction: In recent years, there has been increasing interest in diagnosing various components of chronic obstructive pulmonary disease (COPD) using high-resolution computed tomography (HRCT). The present study was undertaken to evaluate HRCT features in patients with COPD. Methods: 40 male patients with COPD (age 40 years or older) and with a significant smoking history (20 pack-years or more) were included in the study. They were evaluated for HRCT features including vascular attenuation and distortion, mosaic attenuation pattern, directly visible small airways, low attenuation areas of emphysema and measures of hyperinflation of the lungs: tracheal index, sterno-aortic distance, thoracic cage ratio and thoracic cross-sectional area. Results: The tracheal index ranged from 0.46 to 0.94; Saber-sheath trachea was found in 14 patients. The mean thoracic cage ratio at two levels, carina and 5 cm below carina, were 0.69 (range 0.61-0.78) and 0.73 (range 0.62-0.83), respectively. Sterno-aortic distance at carinal level ranged from 1.43 to 4.55 cm, with a mean of 3.00 cm. Directly visible small airways was the commonest finding (36 patients), followed by vascular attenuation (25 patients), mosaic attenuation pattern (16 patients) and vascular distortion (8 patients). Among various subtypes of emphysema, centriacinar emphysema was commonest (16 patients), followed by paraseptal (13) and panacinar emphysema (11). Conclusion: There are certain specific HRCT features of emphysema and it is possible on HRCT to identify the subtypes of emphysema, such as centriacinar, panacinar and paraseptal emphysema. Various features of hyperinflation can also be well identified and quantified on HRCT.