Asbestosis and cryptogenic fibrosing alveolitis: a radiological and functional comparison.

This study compares the relationship between lung function and radiological abnormality in 46 subjects with asbestosis and 38 subjects with cryptogenic fibrosing alveolitis. Radiographs were graded separately by two observers according to the 1980 International Labour Organisation criteria for classification of the pneumoconioses. The correlation between the transfer factor of the lungs and the radiographic profusion of small parenchymal opacities was found to be greater in subjects with asbestosis than in subjects with cryptogenic fibrosing alveolitis. At any level of radiological profusion transfer factor was higher in cases with asbestosis than in cases with fibrosing alveolitis. As pleural thickening is seen commonly in asbestosis and may influence lung volumes and the ratio of transfer factor to effective alveolar volume, the results of these measurements were compared only in the cases showing absent or minimal pleural thickening. Both of these variables were higher in the subjects with asbestosis. The results indicate that despite pathological, functional and radiographic similarities, lung function for a given degree of radiographic parenchymal abnormality is better in subjects with asbestosis than in subjects with cryptogenic fibrosing alveolitis, and that changes in the plain chest x-ray appearances in asbestosis correlate more closely with the results of lung function tests.