Asbestosis and other pulmonary fibrosis in asbestos-exposed workers: high-resolution CT features with pathological correlations

Our plain-English summary of Asbestosis and other pulmonary fibrosis in asbestos-exposed workers: high-resolution CT features with pathological correlations, by H. Arakawa, T. Kishimoto, K. Ashizawa, et al (European Radiology, 2016).

The study

• Authors: H. Arakawa, T. Kishimoto, K. Ashizawa, K. Kato, K. Okamoto, K. Honma, S. Hayashi, M. Akira
• Journal: European Radiology
• Published: 2016;26(5):1485-92
• Cited by: 23 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: The purpose was to identify distinguishing CT features of pathologically diagnosed asbestosis, and correlate diagnostic confidence with asbestos body burden.

Methods: Thirty-three workers (mean age at CT: 73 years) with clinical diagnoses of asbestosis, who were autopsied (n = 30) or underwent lobectomy (n = 3), were collected. Two radiologists independently scored high-resolution CT images for various CT findings and the likelihood of asbestosis was scored. Two pathologists reviewed the pathology specimens and scored the confidence of their diagnoses. Asbestos body count was correlated with CT and pathology scores.

Results: Pathologically, 15 cases were diagnosed as asbestosis and 18 cases with various lung fibroses other than asbestosis. On CT, only the score of the subpleural curvilinear lines was significantly higher in asbestosis (p = 0.03). Accuracy of CT diagnosis of asbestosis with a high confidence ranged from 0.73 to 0.79. Asbestos body count positively correlated with CT likelihood of asbestosis (r = 0.503, p = 0.003), and with the confidence level of pathological diagnosis (r = 0.637, p < 0.001).

Conclusions: Subpleural curvilinear lines were the only clue for the diagnosis of asbestosis. However, this was complicated by other lung fibrosis, especially at low asbestos body burden.

Key Points: • Various patterns of pulmonary fibrosis occurred in asbestos-exposed workers. • The fibre burden in lungs paralleled confident CT diagnosis of asbestosis. • The fibre burden in lungs paralleled confident pathological diagnosis of asbestosis. • Subpleural curvilinear lines were an important CT finding favouring asbestosis.

In plain English

This retrospective Japanese study examined 33 asbestos-exposed workers (31 men, two women) with lung fibrosis. They had chest CT between 2000 and 2011 at six hospitals. Thirty were autopsied and three had a lung lobe removed for lung cancer. Jobs included asbestos manufacturing, shipyard work and asbestos spraying. Two pathologists, unaware of work histories, examined lung tissue. They judged 15 cases to be asbestosis and 18 to be other fibrosis, including usual interstitial pneumonia and mixed dust fibrosis. Two radiologists, unaware of the tissue diagnoses, scored high-resolution CT scans. Only subpleural curvilinear lines (lines a few millimetres from the pleural surface) differed significantly. They were seen in 86.7% of asbestosis cases versus 50% of the others. Counting probable or definite CT ratings as positive, with the tissue diagnosis as reference, the radiologists' accuracy was 0.73 and 0.79. Higher asbestos body counts correlated with higher CT and pathology scores for asbestosis. The authors concluded that these lines were the sole CT difference, and that the likelihood of asbestosis on CT and pathology paralleled asbestos body count. They noted the small number of cases and possible selection bias.

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: Retrospective, multicentre study comparing high-resolution CT findings with pathology from autopsy or lobectomy
• Who was studied: 33 asbestos-exposed workers with lung fibrosis (31 men, two women, mean age at CT 73 years), from six hospitals in a nationwide Japanese network caring for asbestos workers, who had chest CT between May 2000 and July 2011. 30 were autopsied and 3 had lobectomies for lung cancer. 23 of 56 collected cases were excluded.
• Exposure: Occupational asbestos exposure: asbestos manufacturing (9), shipyard work (8), asbestos spraying (4), boiler repair (2), insulation work (2), plumbing (2), other (5). Working years ranged from 10 to 42 (mean 24). Fibre types were not reported.
• Main results:
  • On pathology, 15 cases were classified as asbestosis and 18 as non-asbestosis.
  • Non-asbestosis cases included usual interstitial pneumonia (UIP, 5), unclassifiable chronic interstitial pneumonia (4) and mixed dust fibrosis (2). The remaining cases had discordant pathological diagnoses.
  • Agreement between the two pathologists was excellent (weighted kappa 0.80).
  • Agreement between the two radiologists on the diagnosis of asbestosis was 0.56 (weighted kappa).
  • Subpleural curvilinear line scores were the only CT score that differed significantly: 2.9 in the asbestosis group versus 1.7 in the non-asbestosis group (p=0.03 in text).
  • Subpleural curvilinear lines were present in 86.7% of asbestosis cases versus 50% of non-asbestosis cases (p=0.034).
  • Honeycombing was seen less often in asbestosis (40%) than in non-asbestosis (66.7%), but the difference was not significant (p=0.17).
  • Two patients with asbestosis did not show pleural plaque on CT.
  • Counting a CT score of 2 or more (probable or definite asbestosis) as a high likelihood of asbestosis, with the pathological diagnosis as the gold standard: sensitivity, specificity and accuracy were 0.67, 0.78 and 0.73 for one radiologist, and 0.73, 0.83 and 0.79 for the other.
  • Mean asbestos body count was 1,464,711 in the asbestosis group and 98,745 in the non-asbestosis group (p less than 0.001).
  • Asbestos body count correlated positively with the CT asbestosis score (r=0.503, p=0.003) and with the pathological asbestosis score (r=0.637, p less than 0.001).
• The authors' conclusion: The authors concluded that subpleural curvilinear lines were the sole CT finding that differed between asbestosis and non-asbestosis, and that the CT likelihood and pathological confidence of asbestosis paralleled the asbestos body count.
• Limitations the authors state:
  • CT images were taken with patients lying on their backs, which might make some findings harder to analyse.
  • The number of cases was small.
  • Including only patients with a pathological diagnosis, mostly from autopsy, could introduce selection bias.
  • The interval between CT and pathology was long, with a mean of 16 months.
  • Asbestos bodies were counted, not asbestos fibres.

Topics

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

Medical terms in this study, explained in our Lexicon: Pulmonary Fibrosis, High-Resolution CT (HRCT), Asbestos Body Formation, Pathology, Subpleural Curvilinear Line, Fibrosis.

Related studies

• The comparison of high-resolution computed tomography findings in asbestosis and idiopathic pulmonary fibrosis — M. Akira, K. Morinaga (2016)
• Specificity of high-resolution CT findings in pulmonary asbestosis: do patients scanned for other indications have similar findings? — C.J. Bergin, R.A. Castellino, et al. (1994)
• Asbestosis: high-resolution CT-pathologic correlation — M. Akira, S. Yamamoto, et al. (1990)
• Pulmonary function, smoking habits, and high resolution computed tomography (HRCT) early abnormalities of lung and pleural fibrosis in shipyard workers exposed to asbestos — S. Neri, P. Boraschi, et al. (1996)
• Agreement between chest radiography and high-resolution computed tomography in diagnosing dust-related interstitial lung fibrosis — R.R. Tiwari (2015)
• Asbestos-related pleural and parenchymal fibrosis: detection with high-resolution CT — D.R. Aberle, G. Gamsu, et al. (1988)

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