HRCT und Asthma Bronchiale: Visualisierung Pathophysiologischer Veränderungen des Lungenparenchyms nach Inhalativer Provokation

Purpose: To characterize parenchymal lung affections morphologically in patients with asthma and healthy subjects by high resolution computed tomography (HRCT) subsequent to histamine-triggered inhalation bronchoprovocation and salbutamol-induced broncholysis, and to compare the results with pulmonary function tests. Materials and Methods: Fifteen asthmatics with bronchial hyperreactivity, with a > 20% decrease in FEV1 and a > 10 mmHg decrease in PaO₂ after bronchoprovocation (PC20%+), twelve asthmatics with a < 20% decrease in FEV1 and a > 10 mmHg decrease in PaO₂ after bronchoprovocation (PC20%-), and eight healthy persons without bronchial hyperreactivity underwent inhalation bronchoprovocation and broncholysis. Spirometer-triggered HRCT at high lung volumes was performed, and total and peripheral lung densities and the amount of solid lung structures, representing predominantly vessels, were measured. Results: After bronchoprovocation, we observed significant decreases in total and peripheral lung densities in all groups (p < 0.0005), and a significant increase in lung densities subsequent to bronchodilation (p < 0.0002). The morphological alterations in solid lung structure were not significantly different after bronchoprovocation or broncholysis (p > 0.05), as compared to the baseline measurements. In hyperreactive patients, PaO₂ significantly decreased after provocation and significantly increased after lysis (p < 0.05). In PC20%+ asthmatics, a mean reduction of 27.8 % in FEV1 was observed, which was < 20% in the other groups. No significant correlations were observed between radiological data and the results of pulmonary function tests. In healthy persons, we demonstrated highly significant parenchymal response to bronchoprovocation and broncholysis, which was not otherwise documented by pulmonary function tests. Conclusion: In both PC20%+ and PC20%- patients as well as in healthy individuals, HRCT was efficient in the evaluation of pathoanatomical alterations of the lung parenchyma subsequent to inhalation provocation. In healthy individuals, these parenchymal alterations were not documented by pulmonary function tests.