effects of chronicity on high resolution computed tomography findings in asthma

ABSTRACT

Remodeling is the late result of chronic inflammation in untreated asthma. Remodeling causes resistance to classic asthma therapy, but the time required for this change has not been confirmed, yet. High resolution computed tomography [HRCT] is the only noninva sive method to confirm the structural change in the bronchial wall. The objective of this study was to evaluate the frequency of remodeling in chronic asthma as well as determine the proposed time required for developing remodeling. Non smoker asthmatic patients with more than one year of duration who referred to the sub specialty clinic of pulmonary participated in our study. History, physical examination and spirometric evaluation were done. Diagnosis of asthma was confirmed according to GINA guidelines. CT scan of the lungs was performed in a deep inspiration using Phillips Spiral Multi Slice [1.5 mm thickening]. The images were evaluated by two radiologists. The main group was divided in two groups The patients with more than 5 years of duration of the disease, and those who had been infected with the disease for less than 5 years. The results were then compared with each other. Seventy four subjects participated in this study [40 females, 34 males]. In asthmatic patients with a history of more than 5 years, the mean of age was 51 15.5 years. This group showed no significant difference from the other group with a duration of lower than 5 years [mean age 45 18.26 years]. The most frequent clinical disorder in both groups was found to be dyspnea [98/6%]. The symptoms found in the subjects with abnormal HRCT were ranking from the most to the least frequent as bronchial dilation [22, 30%], mosaic pattern [12, 16%]; both bronchial wall thickening and modularity pattern [11, 15%], and emphysema [9, 12%]. HRCT findings were normal in 32% of subjects. Diagnostic criteria of remodeling in subjects with duration of 1-5 years were not significantly different from those in the subjects who were infected for over 5 years. Bronchial dilation and thickening of bronchus are the best criteria for diagnosing remodeling, but remodeling may occur earlier than the expected time