Comparative study of high resolution computer-assisted tomography with chest radiograph in silicosis

The diagnosis of silicosis is based on the history of exposure to silica dust associated with the radiological alterations compatible with the disease. With the main objective of comparing the alterations found in the chest radiography to those of high resolution computed tomography 49 patients with silicosis were selected. These imaging methods were evaluated separately by three readers and the results summarized through the median of the readings. The following alterations were analysed: nodules, coalescences, large opacities, lynfadenopathy. The patients were male, at an average age of 47.1 years, the majority being sandblasters, with an average exposure time to dust of 15.3 years. When the chest radiography was compared to high resolution computed tomography the following alterations were observed: i) the high resolution computed tomography showed greater profusion of nodules in 19 cases; ii) the high resolution computed tomography detected isolated coalescence and large opacities in 28 cases, seven of them who were classified initially as having simple silicosis were later changed to the complicated form; iii) the high resolution computed tomography was superior in the evaluation of lynfadenopathy in 16 cases. So, from the 49 analysed patients the high resolution computed tomography was more sensitive than the chest radiography in the evaluation of the alterations studied in 38 (77,5%) cases. Other alterations such as cavities, pleural thickening and emphysema were also observed only by this method in 5 cases. In the last 6 (12,2%) cases the high resolution computed tomography did not add any data when compared to chest radiography, four of these showed the initial form of the disease.