Objective To compare the ability to present small opacities on high kilovoltage plain chest film versus high-resolution computed tomography (HRCT).
Methods A retrospective analysis was conducted on HRCT and high kilovoltage plain chest films performed in 137 workers (125 males and 12 females) who were exposed to dust occupationally arc welding fumes, n=56; SiO2 dust, n=37; other dusts (aluminum, graphite, cement, etc.), n=44. HRCT examination consisted of a series of 2-mm-thick sections with 10-mm intersection spacing from the apex of lungs to the diaphragm. All images were photographed and observed at window widths of 1 500 HU and levels of -700 HU. The profusion of small opacities on chest radiography was compared with that on HRCT. CT and radiographic profusion total scores were also compared.
Results There was a correlation between HRCT and radiography in the profusion scores of small opacities (r=0.655, P<0.01). HRCT showed a higher ability to present small opacities than high kilovoltage plain chest film (P<0.01). The HRCT scans found 115 cases with small opacities (type s=86; type p=5; type p/s=8; type s/p=15; type q=1), while the chest radiography saw 86 cases with small opacities (type s=25; type p=5; type p/s=28; type s/p=24; type q/p=3; type q/s=2). When the chest radiographs showed small opacities (n=86), 6 cases showed no abnormality on HRCT (7%). While the chest radiographs were normal in 50 cases, small opacities were detected on HRCT in 34 cases (68%). The upper and posterior lung predominance of small opacities was obvious on HRCT.
Conclusion The chest HRCT is complementary to plain radiography for better early detection of small opacities, and therefore possesses good diagnostic value for accurately evaluating small opacities.
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