Evaluation of high-resolution computed tomography findings in heavy-smokers and it's correlation with respiratory function tests

Background: A large number of lung diseases fall under the category of smoking induced lung diseases, which being the lung cancer and chronic obstructive pulmonary disease (COPD). The relationship between the risk of having a smoking related lung disease and various factors such as starting age, duration of smoking, daily cigarette consumption and smoking intensity has been demonstrated in earlier researches. Even though the chest X-ray is most widely used for examination of lung parenchymal abnormalities caused by smoking, it is proven to be insufficient in some cases and to have limitations in detecting the early stage pathological changes. Yet, in some cases CT(computed tomography) scans with routine thorax protocol have been observed to be of limited value in detecting some pathologies such as emphysema and bronchiectasis. Studies have shown that another common method called high resolution computed tomography (HRCT), using different scan parameters, has a high specifity and sensitivity in detecting pathologies leading to airway obstruction and airway trapping. Pulmonary function tests (PFT) of cigarette smoking individuals have not resulted in significant alterations in early stages. In earlier studies, it has been suggested that HRCT produced better results in early detection of parenchymal pathologies than PFT. Objective: The aim of this study is to identify the HRCT incidences in the lungs of cigarette smoking and non-smoking individuals and to examine the correlation between the results of HRCT and pulmonary function tests. Materials and methods: This study included 155 cases in total, which is composed of 110 heavy smokers and 45 non-smoker individuals who reported various pulmonary complaints such as dyspnea, fever. All individuals first underwent a PFT, immediately followed by HRCT scans. In these tests, various pulmonary abnormalities have been identified, such as micronodules in lung parenchyma, bronchiectasis, bronchial wall thickening, emphysema, presence of atelectasis, areas of ground glass attenuation, interstitial patterns and sequel changes localisations and the results for each individual case have been recorded in registration forms. A statistical comparison of HRCT findings in the sample group and the correlation of these results with PFT results have been analysed. Results: The cigarette consumption has been observed to be 40.32±23.5 packs per year for 41 active smokers and 36.17±19 packs per year for ex-smokers. For 127 of the cases in total no indication of airway obstruction symptoms have been identified in pulmonary function tests. The number of cases for which there were airway obstruction symptoms was 28. The scores of cigarette smokers and non-smoker individuals on centrilobular emphysema and bronchial wall thickening were significantly different(p=0.02, p=0.001). When the HRCT findings of normal and altered PFT cases were compared, emphysema and bronchial wall thickening have been observed at higher rates in the cases with PFT abnormalities in comparison to the ones with normal PFTs(p=0.002, p=0.005). Conclusions: HRCT is effective in identification of a large number of pathological symptoms even when PFT depicts no abnormalities and thus it is of crucial importance in early detection of smoking induced pulmonary diseases.