The value of high resolution computed tomography in the diagnostics of small opacities and complications of silicosis in mine machinery manufacturing workers, compared to radiography.

The purpose of this study was to assess the value and usefulness of high resolution computed tomography (HRCT) in the diagnostics of small opacities and complications of silicosis in mine machinery manufacturing workers, compared to conventional radiograms. The diagnosis of silicosis is mainly based on the radiological findings of workers exposed to the dust causing lung fibrosis. However, on radiograms many parenchymal structures overlap, which limits the sensitivity and specificity of the method. Difficulties in accurate interpretation of conventional radiograms in silicosis also result from their relatively low resolution. We randomly selected 30 I period silicosis patients from 77 I period silicosis patients working at a mine machinery manufacturing company. Out of 1078 non-silicosis and 162 0+ period silicosis subjects, 30 non-silicosis and 30 0+ period silicosis subjects were randomly selected and matched with the 30 I period silicosis subjects by age (+/- 3.0 yr) and occupational exposure time (+/- 2.0 yr). Chest X-rays were taken at maximal inspiration. For the HRCT examination, the GE Somatom plus apparatus was used. Eight, five and six subjects were respectively diagnosed as 0+, I or I+ period silicosis based on HRCT among 90 subjects whose original diagnoses were non-silicosis, 0+ or I period silicosis based on radiography. The numbers of small opacities in HRCT scans were significantly higher than those seen in radiography in all lung zones (p<0.01). HRCT was more sensitive than radiography in detecting small opacities of mid-out zones of the lung, but no statistical significance was found between the two methods in the detection of small opacities of lower zones of the lung. A statistically significant increase in the detectability of bulla, emphysema, pleural, mediastinal and hilar changes was observed (p<0.05). HRCT might be more sensitive than radiography in detecting lung parenchymal changes suggestive of silicosis.

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