The value of computerised axial tomography in the assessment of workers exposed to asbestos

Our plain-English summary of The value of computerised axial tomography in the assessment of workers exposed to asbestos, by G.K. Sluis-Cremer, R.G. Thomas, I.B. Schmaman (American Journal of Industrial Medicine, 1984).

The study

• Authors: G.K. Sluis-Cremer, R.G. Thomas, I.B. Schmaman
• Journal: American Journal of Industrial Medicine
• Published: 1984;6(1):27-35
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000579).

Abstract

Nineteen men who had been exposed to asbestos for long periods were subjected to an examination of the lungs by means of computerised axial tomography (CT). Some features of asbestos-related disease are shown better on CT than on conventional roentgenograms, and occasionally features not shown at all on conventional films may be demonstrated on CT. It was concluded that CT may be useful in cases with borderline and doubtful signs on conventional films, and very occasionally in persons with long exposure who have normal conventional films.

In plain English

Researchers in Johannesburg, South Africa, compared lung CT scans with conventional chest X-rays in 19 men with long asbestos exposure. Eight had worked in mine mills with crocidolite or amosite; 11 had worked in an asbestos cement factory with chrysotile and crocidolite, some also with amosite. Nine men's X-rays had been read as 0/0 on the ILO scale for lung scarring (interstitial fibrosis), though one of them had marked pleural change. In all four men whose X-rays showed well-established irregular shadows (category 1/1 or higher), CT showed fibrosis, and in three it tended to show more fibrotic change than the X-rays. CT found pleural plaques missed on X-ray in three men, while X-rays showed plaques not seen on CT in three others. CT told fat outside the pleura apart from pleural thickening more easily than high-kilovoltage X-rays. The authors concluded that CT and X-rays are complementary and that CT did not consistently show disease earlier. In their opinion, CT should be limited to cases with doubtful or disputed X-rays, or with suggestive clinical or lung function changes despite a "normal" X-ray.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Case series comparing chest CT scans with conventional chest X-rays, read by the ILO classification, in asbestos-exposed workers
• Who was studied: 19 men with long asbestos exposure: 8 mine mill workers and 11 asbestos cement factory workers. The authors worked in Johannesburg, South Africa. Study dates are not given.
• Exposure: Mine mill workers: long, relatively heavy exposure to crocidolite or amosite. Asbestos cement factory workers: chrysotile and crocidolite, and in some cases some amosite. Service ranged from 7 to 37 years in the table. No fiber measurements are given.
• Main results:
  • In 9 of the 19 men, conventional X-rays had been read as 0/0. In two they were read as 0/1, meaning fibrosis was suspected but then rejected.
  • Among the men read as 0/0, case 16 had marked pleural change. In this case the lung function values were not all within normal limits.
  • In all four men whose X-rays showed well-established irregular opacities (1/1 or higher; cases 5 to 8), CT showed fibrosis. In cases 6, 7 and 8, CT tended to reveal more fibrotic change than the X-rays.
  • Four men had early asbestosis on X-ray (read as 1/0; cases 3, 4, 18 and 19). Of these, all except case 19 showed some redistribution of blood flow on CT. Only case 4 showed extensive posterior fibrosis.
  • Pleural plaques were seen on CT but not on X-ray in cases 1, 9 and 18. Plaques were seen on X-ray but not on CT in cases 4, 5 and 19.
  • In case 10, CT showed a 1-cm coin lesion that could not be seen on X-ray. It did not change over 8 months of observation, and the authors judged it probably benign.
  • Fat outside the pleura (extrapleural fat) was told apart from pleural thickening more easily on CT than on high-kilovoltage X-rays.
• The authors' conclusion: The authors concluded that CT and conventional X-rays are complementary, and that CT did not consistently show lung or pleural change earlier, though fibrosis, when present, was shown more strikingly on CT. In their opinion, CT should be limited to cases with doubt or controversy on conventional X-rays, or with suggestive clinical or lung function changes despite a "normal" X-ray.
• Limitations the authors state:
  • The authors found recognising and measuring the CT sign of blood-flow redistribution highly subjective.
  • In men with normal X-rays and no fibrosis on CT, the authors judged moderate fibrosis unlikely, but said slight or minimal fibrosis could not be excluded.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis.

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