AbstractIn the present study, the diagnostic yield of high resolution computed tomography (HRCT) is evaluated in patients with thoracoscopically-verified idiopathic spontaneous pneumothorax (SP). Visual assessment as well as densitometry of lung parenchyma was performed. In eight of the 20 prospectively-evaluated SP patients, emphysema-like (EL) changes such as blebs and bullae could be detected. The SP patients with EL changes were significantly older and were more heavy smokers. Spirometrically-controlled CT lung densitometry showed no differences between the patient group with or without these EL changes. Comparing the densitometric measurements of the patient group with a healthy control group no significant differences in densitometry between both groups were found.In conclusion, this study confirms that HRCT is a reliable method of detecting blebs and bullae in patients with spontaneous pneumothorax. Furthermore CT lung densitometry revealed no parenchymal abnormalities or signs of air trapping in patients with spontaneous pneumothorax