3-Dimensional Quantification of Composite Pleural Plaque Volume in Patients Exposed to Asbestos Using High-resolution Computed Tomography: A Validation Study

Our plain-English summary of 3-Dimensional Quantification of Composite Pleural Plaque Volume in Patients Exposed to Asbestos Using High-resolution Computed Tomography: A Validation Study, by G. Dournes, A. Dubois, I. Benlala, et al (Journal of Thoracic Imaging, 2019).

The study

• Authors: G. Dournes, A. Dubois, I. Benlala, A. Lacourt, C. Paris, A. Gislard, B. Clin, J.C. Pairon, F. Baldacci, F. Laurent
• Journal: Journal of Thoracic Imaging
• Published: 2019;34(5):320-325
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Rationale: As pleural plaque has been reported as a risk factor in the occurrence of lung cancer and mesothelioma, a reproducible and precise method of measurement of pleural plaque volume (PPV) is needed to further describe these relationships. The aim of the study was to assess the reproducibility of a 3-dimensional computed tomography (3D-CT) volumetric analysis of PPV in patients with occupational exposure to asbestos.

Material And Methods: A total of 28 patients were retrospectively randomly selected from the multicenter APEXS (Asbestos Post Exposure Survey) study, which was held between 2003 and 2005. All patients underwent a 3D-CT scan. Two readers specialized in chest radiology completed the 3D semiautomated quantification of lung volume using dedicated software. They also had to categorize the visual extent of pleural plaque in terms of thickness and circumference. Reproducibility of the continuous PPV variable was assessed using the intraclass correlation coefficient (ICC) and Bland-Altman analysis. Reproducibility of categorical variables was assessed using the κ test.

Results: Intraobserver reproducibility of PPV was almost perfect (ICC=0.98 [95% interval: 0.97-0.99]), and interobserver reproducibility was very good (ICC=0.93 [0.88-0.97]). At Bland-Altman analysis, the mean differences were 0.1 (limit of agreement: -11.0 to 11.2) and 3.7 cc (-17.8 to 25.2), respectively. Visual analysis of both plaque in terms of thickness and circumference were fair to moderate, with κ values ranging from 0.30 to 0.60.

Conclusions: 3D semiautomatic quantification of PPV is feasible and reproducible using CT in patients with occupational exposure to asbestos. PPV measurement may be useful to correlate with other asbestos-related disease outcomes and prognosis.

In plain English

This study tested software-assisted measurement of pleural plaque volume on 3-dimensional CT scans. The authors randomly selected 100 people from a 2003 to 2005 French survey of occupational asbestos exposure (APEXS). After two exclusions, 28 of the 98 remaining had plaques; all were men, mean age 77.2. Two readers measured plaque volume, and one measured it twice. Agreement was almost perfect within one reader (ICC 0.98, 95% interval 0.97 to 0.99) and very good between readers (ICC 0.93, 0.88 to 0.97). Visual grading of plaque thickness and extent showed fair to moderate agreement (kappa 0.30 to 0.60). Among all 98, the software alone missed no one with plaques (sensitivity 100%, 95% CI 87 to 100) but wrongly flagged 40 of the 70 people without plaques (specificity 42%, 95% CI 31 to 55). After the readers corrected 38 of these, specificity was 97% (95% CI 90 to 99) for both readers. The authors concluded the method is feasible and reproducible. They noted the study was retrospective, needed substantial manual editing, and examined neither clinical outcomes nor change over time.

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 validation (reproducibility) study of a 3D semiautomatic CT measurement method, using scans from an existing population study
• Who was studied: 100 participants randomly selected from the multicenter APEXS study in France (October 2003 to December 2005, up to 5511 participants). 2 were excluded for contrast-enhanced CT. 28 of the remaining 98 had pleural plaques and formed the main study group: all 28 were men, mean age 77.2 years.
• Exposure: Occupational asbestos exposure. In the 28 patients with plaques, mean total duration was 32.2 ± 8.2 years, the cumulated exposure index was 92.0 ± 106.7, and the mean maximum exposure level was 3.3 ± 0.7 on a 1 (low) to 4 (high) scale. The article does not name fiber types.
• Main results:
  • Repeated measurements of pleural plaque volume by the same reader showed almost perfect agreement in the 28 patients with plaques (ICC = 0.98, 95% interval 0.97-0.99).
  • Pleural plaque volume measurements by the two different readers showed very good agreement (ICC = 0.93, 0.88-0.97).
  • Bland-Altman analysis gave a mean difference of 0.1 cubic centimetres within one reader (limits of agreement -11.0 to 11.2) and 3.7 cubic centimetres between readers (-17.8 to 25.2). The article prints the unit as cc3.
  • Plaque volume expressed as a percentage of lung volume showed an ICC of 0.98 within one reader and 0.95 between readers.
  • Visual grading of plaque thickness showed moderate agreement: kappa 0.60 within one reader and 0.55 between readers.
  • Visual grading of plaque extent showed moderate agreement within one reader (kappa 0.56) and fair agreement between readers (kappa 0.30).
  • The software alone was tested on 98 participants: 28 with plaques and 70 without. It had no false negatives (sensitivity 100%, 95% CI 87-100). It produced 40 false-positive patients among those without plaques, a specificity of 42% (95% CI 31-55).
  • The readers corrected 38 of the false positives. After this correction, sensitivity was 100% (87-100) and specificity was 97% (90-99) for both readers.
  • Mean time to complete the 3D quantification was 16.3 ± 4.2 minutes for Reader1 and 12.1 ± 4.8 minutes for Reader2.
• The authors' conclusion: The authors concluded that 3D semiautomated quantification of pleural plaque volume is feasible using CT, and that it showed very good to almost perfect reproducibility. They judged that it performed better than visual analysis for quantifying disease extent, and that larger and longitudinal studies are warranted.
• Limitations the authors state:
  • The study was a first attempt to validate the method and was retrospective.
  • Patients with lung nodules (3) and asbestosis (3) were not excluded.
  • No attempt was made to relate plaque volume to clinical or lung function data.
  • The software produced many false positives, so a substantial amount of manual editing was required.
  • No longitudinal analysis was performed, so the prognostic value of the measurement was not assessed.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Pleural plaques and thickening.

Medical terms in this study, explained in our Lexicon: Pleural Plaques, Lung Cancer, Mesothelioma, Occupational Exposure, CT Scan, Prognosis.

Related studies

• Conventional and high resolution computed tomography in the diagnosis of asbestos-related diseases — D.A. Lynch, G. Gamsu, et al. (1989)
• High-resolution computed tomography in cases with environmental exposure to asbestos in Turkey — F. Topçu, H. Bayram, et al. (2000)
• High-resolution computed tomography features of asbestosis versus fibrotic hypersensitivity pneumonitis: an observational study — R. Ma, S. Li, et al. (2022)
• Pleural plaques in asbestos-exposed workers: reproducibility of a new high-resolution CT visual semiquantitative measurement method — G.S. Meirelles, J.I. Kavakama, et al. (2006)
• Agreement between chest radiography and high-resolution computed tomography in diagnosing dust-related interstitial lung fibrosis — R.R. Tiwari (2015)
• High-resolution computed tomography of asbestos-related diseases — D.R. Aberle (1991)

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