CT findings of diffuse pleural disease

This is a comprehensive study on the usefulness of CT in the evaluation of diffuse pleural diseases in 114 patients. Alterations of the pleura and extrapleural fat were analyzed. The pleural changes were classified into five groups: no thickening (group 1), focal thickening (group 2), diffuse smooth thickening (group 3), diffuse nodular thickening less than 10 mm (group 4), diffuse nodular thickening more than 10 mm (group 5). CT findings of group 1 were mostly found in patients with transudatory effusion; group 2 in all patients with asbestosis; group 3 in those with empyema; and groups 4 and 5 in those with malignant pleural diseases. In some cases of malignant pleural diseases and asbestosis, mediastinal and/or fissural thickening was present. Circumferential pleural thickening (pleural rind) was only seen in malignant pleural diseases. Pleural calcification was present in chronic empyema and asbestosis. Increased thickness of the extrapleural fat was seen in malignant pleural diseases and empyema, but homogeneous increased attenuation of the extrapleural fat might be a specific finding in acute empyema. The author concludes that CT is useful in the evaluation of pleural changes and alterations of extrapleural fat with diffuse pleural diseases, particularly in the pattern recognition based on CT classification. (author)