High Resolution Computed Tomography and Lung Function in Asbestos-exposed Workers with Normal Chest Radiographs

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Abstract
Asbestos-exposed persons with normal chest radiographs can demonstrate parenchymal abnormalities on high resolution computed tomography (HRCT). We reviewed the HRCT, clinical presentation, and results of pulmonary function tests in 169 asbestos-exposed workers with normal chest radiographs (ILO < 1/10). The HRCT was normal or near normal in 76 subjects (Group 1), abnormal but intermediate for asbestosis in 36, and abnormal and suggestive of asbestosis in 57 (Group 2). The indeterminate subjects were excluded from further analysis. The subjects in Groups 1 and 2 were not significantly different in their duration of asbestos exposure, latency, smoking history, or in measurements of airflow obstruction (FEV1/FVC% and %FEV1). Both in vital capacity percent predicted and diffusing capacity percent predicted were significantly lower in the abnormal subjects (Group 2) than in the normal subjects (Group 1) (79.0 versus 86.2, p = 0.005; 78.2 versus 87.1 p = 0.024; independent t test). We conclude that in asbestos-exposed subjects with normal chest radiographs, HRCT can identify a group of subjects with significantly reduced lung function indicative of restrictive lung disease when compared with a group with normal or near-normal HRCT.