Computed chest tomography in rats with pulmonary damage due to microembolism

Computed chest tomography was performed in 13 rats with pulmonary damage due to microembolism, caused by injection of thrombin (500 NIH/kg body weight) and tranexamic acid, a fibrinolytic inhibitor (200 mg/kg body weight), and in 9 control rats. The purpose of the investigation was to perform attenuation measurements at two levels of the right lung, each with three regions of interest (anterior, mid and posterior). Alterations in attenuation, compared with controls, were correlated with lung weight. Compared with controls, the attenuation was significantly increased in the anterior and posterior regions at both levels in animals with pulmonary damage, but not in the mid regions. There was a statistically significant correlation between increasing attenuation and increasing lung weight. A significant difference was found between damaged and control lungs regarding the microscopic grade of interstitial oedema, alveolar oedema and fibrin. Histograms of attenuation values in computed tomograms might be of value in detecting alveolar oedema. It is concluded that computed chest tomography is a good method for detecting pulmonary oedema at an early stage of experimental microembolism in the rat.