Quantification of pleural plaques by computed tomography and correlations with pulmonary function: preliminary study

Our plain-English summary of Quantification of pleural plaques by computed tomography and correlations with pulmonary function: preliminary study, by Y.K. Cha, J.S. Kim, J.H. Kwon (Journal of Thoracic Disease, 2018).

The study

• Authors: Y.K. Cha, J.S. Kim, J.H. Kwon
• Journal: Journal of Thoracic Disease
• Published: 2018;10(4):2118-2124
• Cited by: 8 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: The aims of this study were to quantify pleural plaque volumes (PPVs) by computed tomography (CT) and investigate relations between PPV and pulmonary function after excluding other factors that might affect pulmonary function.

Methods: Twenty-six subjects with pleural plaques and pulmonary function test (PFT) results among 1,544 subjects that registered with the Korea Environment Corporation for asbestos damage relief from January 2011 to December 2015 were included. Subjects with CT evidence of lung diseases and/or previous surgery were excluded. PPVs were measured by tracing the outlines of all pleural plaques on CT images. Patients were allocated to three groups by PPV, as follows, <10, 10-20, or ≥20 mL, and the PFT results of these groups were analyzed and compared. Simple linear regression analysis and multiple regression analysis were used to evaluate correlations between PPV and PFT variables.

Results: No significant relationship was found between total PPV and pulmonary function indices or between PPV groups and PFT results (P>0.05). However, forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and diffusing capacity of the lung for carbon monoxide (DLCO) values in the higher PPV group (≥20 mL) tended to be lower, indicating a restrictive pattern of pulmonary function.

Conclusions: We quantified PPV on CT and found out higher PPV tended to exhibit a restrictive pattern. However, pleural plaques alone were not found to be significantly associated with pulmonary function.

In plain English

This retrospective South Korean study measured pleural plaque volume on CT scans and tested whether it was linked to lung function. From 1,544 people registered for asbestos damage relief between January 2011 and December 2015, the authors included 26 who had lung function tests and whose CT scans showed pleural plaques without other lung disease or previous lung surgery, except trace centrilobular emphysema, which five had. All 26 had lived within 2 km of asbestos mines or asbestos plants, and 18 also had occupational exposure. Two radiologists traced every plaque. Total volumes ranged from 0.64 to 73.48 mL. No statistically significant relationship was found between total plaque volume and lung function. The 7 people with 20 mL or more of plaque had lower FEV1, FVC and DLCO values than the two smaller-volume groups, but the differences were not statistically significant. The authors noted the results were still within normal limits. The authors concluded that higher plaque volume tended toward a restrictive pattern, but that plaques alone were not significantly associated with lung function. They named the small sample size as a limitation.

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 study of CT scans and pulmonary function tests, described in the title as a preliminary study
• Who was studied: The source group was 1,544 people registered with the Korea Environment Corporation for asbestos damage relief from January 2011 to December 2015. Of these, 26 were included. They had pleural plaques on CT and pulmonary function test results. People with CT evidence of other lung diseases, previous pulmonary resection or pleurodesis were excluded, but trace centrilobular emphysema was allowed. The 26 had a mean age of 67.5 years (range 47 to 85) and included 16 men and 10 women.
• Exposure: All 26 had environmental asbestos exposure from living within 2 km of asbestos mines or asbestos handling or manufacturing plants. Of these, 22 lived near a mine, 4 near a factory and 2 had family member exposure. Eighteen also had occupational exposure: 11 in asbestos mining, 6 in asbestos-related product manufacturing and 1 in construction. Fiber types were not named.
• Main results:
  • Five of the 26 included subjects had trace centrilobular emphysema in both lungs. The authors allowed only trace emphysema occupying less than 0.5 percent of a lung zone.
  • Among the 26 subjects, total pleural plaque volume ranged from 0.64 to 73.48 mL. The mean was 18.07 mL, with a standard deviation of 19.73.
  • Simple linear regression found no significant relationship between total plaque volume and lung function results. FEV1: R2 0.03, P=0.398. FVC: R2 0.024, P=0.45. FEV1/FVC: R2 0.003, P=0.786. DLCO: R2 0.081, P=0.187.
  • Multiple regression also showed no significant relationship between total plaque volume and lung function results. Men had a significantly greater mean plaque volume than women (P=0.03).
  • The subjects were split into three groups by plaque volume: under 10 mL (n=11), 10 to 20 mL (n=8) and 20 mL or more (n=7). No group differences were statistically significant. The 20 mL or more group had lower values than the other two groups for FEV1 (88.14 vs 98.0 and 97.0; P=0.178), FVC (83.86 vs 89.91 and 91.75; P=0.475) and DLCO (66.0 vs 80.40 and 93.63; P=0.116). The authors described this as indicating a restrictive pattern.
  • Lung function results did not differ significantly between subjects with and without diaphragmatic, mediastinal, or diaphragmatic plus mediastinal plaques.
  • The authors reported that the relationship between asbestos exposure duration and lung function results was not statistically significant.
  • The authors noted that the lung function results remained within normal limits and may not have real clinical relevance.
• The authors' conclusion: The authors concluded that higher pleural plaque volume showed a trend toward a restrictive pattern. They also concluded that the presence of pleural plaque alone was not significantly associated with pulmonary function.
• Limitations the authors state:
  • The study was retrospective with a limited sample size, and larger studies are needed to validate the results.
  • The number of subjects in each plaque volume group was too small, which limited statistical significance.
  • The tracing method may introduce measurement error. Thin plaques were often hard to tell apart from extrapleural structures or dependent atelectasis.
  • Measuring plaque volumes was time consuming and tedious, so the method would not be easily applied.

Topics

Medical terms in this study, explained in our Lexicon: Pleural Plaques, Pulmonary Function Test (PFT), FEV1, Diffusing Capacity (DLCO).

Related studies

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• Surface of localized pleural plaques quantitated by computed tomography scanning: no relation with cumulative asbestos exposure and no effect on lung function — J. Van Cleemput, H. De Raeve, et al. (2001)
• Asbestos-related lesions of the pleura: parietal plaques compared to diffuse thickening studied with chest roentgenography, computed tomography, lung function, and gas exchange — G. Hillerdal, P. Malmberg, 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)
• Findings from high resolution computed tomography of the lung and pleura of symptom free workers exposed to amosite who had normal chest radiographs and pulmonary function tests — S. Neri, A. Antonelli, et al. (1994)
• Artificial Intelligence-based Quantification of Pleural Plaque Volume and Association With Lung Function in Asbestos-exposed Patients — K.B.W. Groot Lipman, T.N. Boellaard, et al. (2024)

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