CT and functional respiratory tests. Evaluation of efficacy of bronchodilator therapy in chronic obstructive pulmonary disease (COPD).

PURPOSE: To evaluate changes in qualitative and quantitative parameters at high resolution CT (HRCT) and in respiratory function indexes (RFI) after bronchodilator administration in COPD patients. MATERIALS AND METHODS: Fifteen former smokers (9 male and 6 female, mean age 65 years), with COPD were studied. Patients with asthmatic or pulmonary diseases were excluded. After informed consent, the patients underwent blood gas analysis, baseline RFI (respiratory function index), inspiratory/expiratory HRCT, administration of salbutamol and bromide (by metered-dose inhaler), RFI after 45 minutes, and inspiratory/expiratory HRCT. First, we performed a visual qualitative analysis (by means of a preformed questionnaire), and then a quantitative analysis by "density mask" programme at three levels: aortic arch, carina, and supradiaphragmatic level. By using this diagnostic approach we were able to determined the global area of each lung, dependent and independent of density, bronchus-artery ratio, emphysema extension, air trapping, morphologic distortion of the airways. RESULTS: Data correlation analysed through linear regression statistical test. Outstanding correlations were found between the RFI (Raw, SVC, IC, RV, FEV1, VP70) and, respectively, density, global lung areas, and bronchus-artery ratio changes before and after bronchodilators administration. CONCLUSIONS: Our study confirmed the usefulness of bronchodilators and the need for a multiparametric and comparative (radiological and functional) approach to COPD, as well as the usefulness of HRCT in evaluating the response to visible airway physiologic stimulus and extension, and reversibility of air trapping.