Specificity of high-resolution CT findings in pulmonary asbestosis: do patients scanned for other indications have similar findings?

OBJECTIVE

High-resolution CT findings in patients with asbestosis include subpleural curvilinear densities, subpleural density in dependent portions of the lung, parenchymal bands, thickened septal lines, and honeycomb lung. Our objective was to examine the prevalence of these CT findings in a random group of patients scanned for a variety of clinical reasons not specifically related to occupational exposure.

MATERIALS AND METHODS

One hundred sixty-eight CT studies of the thorax were performed at six levels in 168 patients examined for a variety of clinical indications. The scans were evaluated by two radiologists for the presence of subpleural curvilinear densities, subpleural density in dependent locations, parenchymal bands, thickened septal lines, and honeycomb lung.

RESULTS

CT scans of 11 patients showed pleural plaques suggesting previous exposure to asbestos. Among the 157 studies showing no evidence of pleural plaques, CT scans showed subpleural curvilinear densities in dependent areas in 32 (20%); subpleural curvilinear densities in nondependent areas in 19 (12%); parenchymal bands in 47 (30%); thickened septal lines in dependent areas in 93 (59%), and septal lines in nondependent areas in 67 (43%); subpleural density in dependent areas in 66 (42%); and honeycomb lung in five (3%).

CONCLUSION

Subpleural curvilinear densities, subpleural density in dependent locations, parenchymal bands, and thickened septal lines occur as isolated and as combined CT findings in patients with a variety of underlying diseases or conditions unrelated to asbestosis and by themselves are nonspecific findings. Their occurrence, even in patients with CT evidence of pleural plaques, does not necessarily indicate the presence of asbestosis.