Pulmonary uptake of gallium-67 in asbestos-exposed humans and sheep

Our plain-English summary of Pulmonary uptake of gallium-67 in asbestos-exposed humans and sheep, by R. Bégin, A. Cantin, G. Drapeau, et al (The American Review of Respiratory Disease, 1983).

The study

• Authors: R. Bégin, A. Cantin, G. Drapeau, G. Lamoureux, M. Boctor, S. Massé, M. Rola-Pleszczynski
• Journal: The American Review of Respiratory Disease
• Published: 1983;127(5):623-30
• Cited by: 63 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

To evaluate the 67Ga lung uptake as an indicator of inflammatory activity in asbestosis, we obtained 67Ga lung scans in 58 long-term asbestos workers. The 67Ga localized excessively in the lungs of 17 of the 21 workers with asbestosis. Among workers without sufficient criteria for the diagnosis of asbestosis, the 67Ga scan index was significantly increased in 43% (16 of 37). Among the 16 with positive 67Ga scan, abnormal pressure-volume curve and/or gas exchange data were found in 87%, whereas in the 21 workers with negative 67Ga scan, similar abnormalities were found in only 29%. In the sheep model of the disease, bronchoalveolar analysis after 67Ga scan demonstrated that the excessive uptake of 67Ga in asbestosis is caused by enhanced serum protein leakage and macrophage accumulation in the lung. Thus, 67Ga scanning in asbestos workers may be a useful indicator of early lung damage.

In plain English

This study combined gallium-67 lung scans in 58 long-term asbestos workers from the mines and mills of Quebec with scans and lung washings (bronchoalveolar lavage) in 9 sheep given chrysotile asbestos or saline into the airways. Raised gallium-67 uptake was studied as a possible sign of lung inflammation. Of the 58 workers, 21 met criteria for asbestosis: 17 of them had a raised scan index (above 3.5) and 4 did not. Of the 37 workers without asbestosis, 16 had a raised index. Among those 16, abnormal pressure-volume curves and/or exercise gas exchange were found in 87%, compared with 29% of the 21 workers without asbestosis whose scans were normal. Over 3 to 5 years, the X-ray score in the 16 rose from 0.16 to 0.50, and their vital capacity fell by 38 ml per year, against 6 ml per year in those 21 workers. In the sheep, the mean index was 7.0 in the high-dose group, 3.6 in the low-dose group and 2.6 in controls. The authors concluded that raised uptake marks early asbestos-induced lung processes that may or may not lead to pulmonary fibrosis.

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: Clinical study of asbestos workers, in which current findings were compared with each worker's evaluation 3 to 5 years earlier, combined with an animal experiment in sheep
• Who was studied: 58 asbestos workers aged 47 to 70, referred for assessment of suspected asbestosis, all exposed only in the mines and mills of Quebec. Also 26 normal volunteers, used to set the scan cut-off, and 9 sheep (3 controls, 3 low-dose, 3 high-dose).
• Exposure: Workers: asbestos dust in the mines and mills of Quebec for an average of 33 years (range 7 to 43). Sheep: repeated doses of UICC Canadian chrysotile asbestos fibers placed into the airways (total 328 mg in the low-dose group, 2,282 mg in the high-dose group) or saline only.
• Main results:
  • 21 of the 58 workers were diagnosed with asbestosis
  • All 26 normal volunteers had a gallium-67 index below 3.5, which was used as the cut-off
  • Workers were split into four groups: A (no asbestosis, index below 3.5) 21; B (no asbestosis, index above 3.5) 16; C (asbestosis, index above 3.5) 17; D (asbestosis, index below 3.5) 4
  • Mean gallium-67 index was 1.2 in Group A, 4.6 in Group B and 4.9 in Group C (each plus or minus 0.2). The difference was significant between A and B and between A and C, but not between B and C.
  • Over 3 to 5 years, the X-ray score of small opacities rose from 0.16 to 0.50 in Group B (p less than 0.05)
  • Over the same period, the X-ray score rose from 0.41 to 2.86 in Group C (p less than 0.01)
  • Vital capacity changed by -6 ml per year in Group A, -38 ml per year in Group B and -26 ml per year in Group C
  • Abnormal pressure-volume curves and/or exercise gas exchange were found in 29% of Group A, 87% of Group B and 100% of Group C
  • The 4 workers with asbestosis but without X-ray or lung-function signs of progression (Group D) had normal gallium-67 uptake
  • Among the 5 workers who had lung washings, neutrophils averaged 3% of cells in Group B and 10.5% in Group C
  • Sheep: the mean gallium-67 index was 2.6 in controls, 3.6 in the low-dose group and 7.0 in the high-dose group
  • Sheep: the gallium-67 index correlated with total radioactivity in the lung washings (r = 0.76)
  • Sheep: in the high-dose group, radioactivity in the fluid part of the washings paralleled a higher albumin level (r = 0.82)
  • Sheep: per million washing cells, radioactivity did not differ between groups
  • Sheep: cell radioactivity correlated significantly only with macrophage counts
• The authors' conclusion: The authors concluded that raised gallium-67 lung uptake in asbestos workers does not necessarily indicate early asbestosis (fibrosis), but marks early asbestos-induced lung processes that may or may not lead to pulmonary fibrosis. In the sheep, they attributed the uptake to serum protein leakage and macrophage accumulation in the lung.
• Limitations the authors state:
  • On ethical grounds, lung washings and/or biopsy could not be done on all workers, although these would have best assessed disease activity. Only 5 workers had washings and 2 had open lung biopsy.
  • Group D was too small to analyze further

Topics

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

Medical terms in this study, explained in our Lexicon: Macrophage.

Related studies

• Unexpected gallium uptake in benign pulmonary pathology. Report of two cases — R.G. McLean, D. Choy, et al. (1984)
• Assessment of progression of asbestosis in the sheep model by bronchoalveolar lavage and pulmonary function tests — R. Bégin, M. Rola-Pleszczynski, et al. (1983)
• Bronchoalveolar lavage analysis, gallium-67 lung scanning and soluble interleukin-2 receptor levels in asbestos exposure — G.L. Delclos, D.G. Flitcraft, et al. (1989)
• Fibronectin and procollagen 3 levels in bronchoalveolar lavage of asbestos-exposed human subjects and sheep — R. Bégin, M. Martel, et al. (1986)
• Contributions of experimental asbestosis in sheep to the understanding of asbestosis — R. Bégin, A. Cantin, et al. (1991)
• Asbestos-induced lung injury in the sheep model: the initial alveolitis — R. Bégin, M. Rola-Pleszczynski, et al. (1983)

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