[Computed tomography of pneumoconiosis]

This review describes the usefulness of computed tomography (CT) and high-resolution computed tomography (HRCT) in image evaluation in pneumoconiosis. For pneumoconiosis, in the same way as for other diffuse lung diseases, conventional CT includes 10 mm collimation scans at 1 cm intervals from the apex to the base of the lung, whereas HRCT uses five to six 1.2 to 3 mm collimation scans at predetermined representative locations including the aortic arch, the tracheal carina, and 2 cm above the dome of the right hemidiaphragm. The CT scans are performed in the supine position in silicosis and coal workers' pneumoconiosis, and both in the supine and prone position in asbestosis. In silicosis, CT is superior to chest radiography in detecting coalescence of nodules and early stage formation of large opacities. There are good correlations between HRCT findings and histological changes, especially in secondary pulmonary lobules. With HRCT, small nodules are found to be located in the center of the secondary pulmonary lobule in silicotic lungs. The mild emphysematous change associated with silicosis can also be found with HRCT. In coal workers' pneumoconiosis, the HRCT is useful in detecting nodules located in the subpleural and fissural subpleural areas. In asbestosis, the conventional CT can detect pleural plaques more sensitively than chest radiography. HRCT is also especially useful in detecting earlier fibrotic change in asbestosis in lung parenchyma, apparent as subpleural lines, parenchymal bands, subpleural curvilinear line shadows and so on.(ABSTRACT TRUNCATED AT 250 WORDS)