High-resolution computed tomography features of asbestosis versus fibrotic hypersensitivity pneumonitis: an observational study

Our plain-English summary of High-resolution computed tomography features of asbestosis versus fibrotic hypersensitivity pneumonitis: an observational study, by R. Ma, S. Li, Y. Wang, et al (BMC Pulmonary Medicine, 2022).

The study

• Authors: R. Ma, S. Li, Y. Wang, S. Yang, N. Bao, Q. Ye
• Journal: BMC Pulmonary Medicine
• Published: 2022;22(1):207
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Asbestosis and fibrotic hypersensitivity pneumonitis (FHP) share the pathogenetic mechanisms induced bronchiolocentric fibrotic process secondary to inhalation exposure. Under the occupational and environmental mixed exposures, asbestosis and FHP are needed to make the differential diagnoses on high-resolution computed tomography (HRCT), especially in the countries still using asbestos. The study aimed to analyze the HRCT features of asbestosis versus FHP.

Methods: The patients with asbestosis or with HP were sequentially recruited in this comparative study at Beijing Chaoyang Hospital between January 2006 and December 2016. Patients' clinical data were obtained from a predesigned charts. The international classification of HRCT for occupational and environmental respiratory diseases was used to categorize chest imaging findings in patients. The calculation of test statistics was used to compare the imaging features of asbestosis and FHP.

Results: 341 patients with asbestosis and 158 patients with HP were sequentially recruited, among which 204 patients with asbestosis and 74 patients with FHP were eligible for data analysis. Patients with asbestosis were older and had a longer latent period until disease manifestation than those with FHP. Asbestosis was characterized by irregular and/or linear opacities, with lower lung preponderance, accompanied by ground-glass opacities and mosaic attenuation. Notably, 98.5% of patients with asbestosis showed benign pleural abnormalities, and 39.7% of these patients had diffuse pleural thickening with parenchymal bands and/or rounded atelectasis. Abnormalities of the mediastinal and diaphragmatic pleura were observed only in cases of asbestosis, and this finding showed high specificity for the diagnosis for asbestosis compared with that for FHP. Subpleural dots or diaphragmatic pleural abnormalities showed moderate sensitivity and high specificity for diagnosis of asbestosis compared with that for FHP. Interobserver reliability was good for evaluation of imaging findings including honeycombing, pleural calcification, lymphadenectasis, and lymph node calcification.

Conclusions: HRCT-based imaging findings can distinguish between asbestosis and FHP to a certain extent, particularly with regard to subpleural dots and diaphragmatic pleural abnormalities that characterize the former.

© 2022. The Author(s).

In plain English

This retrospective study at Beijing Chaoyang Hospital compared high-resolution CT (HRCT) chest scans of patients newly diagnosed between 2006 and 2016 with asbestosis (204 analyzed) or fibrotic hypersensitivity pneumonitis (FHP, 74 analyzed). FHP is another scarring lung disease linked to inhaled substances. All asbestosis patients had been exposed to chrysotile, and 79 had processed asbestos at home. The asbestosis patients were older and had longer latent periods. Pleural abnormalities appeared in 201 of 204 asbestosis patients (98.5%) and in 57 of 74 FHP patients (77.0%). Visceral-type pleural changes, mediastinal and diaphragmatic pleural abnormalities, and pleural calcification were seen only in asbestosis. Subpleural dots occurred in 56.9% of asbestosis patients versus 13.5% of FHP patients (sensitivity 0.57, specificity 0.86). Diaphragmatic pleural abnormalities had sensitivity 0.59 and specificity 1.00. Ground-glass opacity was more common in FHP, and mosaic attenuation did not differ significantly between the groups. The authors concluded that subpleural dots and diaphragmatic pleural abnormalities can tell the two diseases apart "to a certain extent." They noted a single-center design, a small sample, and no workplace monitoring data for chrysotile exposure.

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 comparative (observational) study of HRCT findings in two patient groups
• Who was studied: Patients newly diagnosed at Beijing Chaoyang Hospital, China, January 2006 to December 2016. Of 341 asbestosis patients recruited, 204 were eligible for analysis. Of 158 hypersensitivity pneumonitis patients screened, 74 with fibrotic HP were eligible.
• Exposure: All asbestosis patients had chrysotile exposure. Most worked in asbestos processing and production, including weaving. The FHP comparison group had exposures to organic antigens such as birds, pets and microbes.
• Main results:
  • Compared with the asbestosis patients, the FHP patients were younger at diagnosis and had shorter exposure times and latent periods (P < 0.001).
  • Of the 204 asbestosis patients, 125 (61.3%) worked in occupations associated with asbestos products and 79 (38.7%) processed asbestos at home.
  • Any pleural abnormality was found in 201 of 204 asbestosis patients (98.5%) and in 57 of 74 FHP patients (77.0%).
  • Visceral-type pleural abnormality was seen in 81 asbestosis patients (39.7%) and no FHP patients.
  • Diaphragmatic pleural abnormality was seen in 121 asbestosis patients (59.3%) and no FHP patients. As a sign of asbestosis versus FHP it had sensitivity 0.59 and specificity 1.00.
  • Mediastinal pleural abnormality was seen in 66 asbestosis patients (32.4%) and no FHP patients.
  • Pleural calcification was seen in 141 asbestosis patients (69.1%) and no FHP patients.
  • Subpleural dots were seen in 56.9% of asbestosis patients versus 13.5% of FHP patients (P < 0.001). For identifying asbestosis versus FHP: sensitivity 0.57, specificity 0.86, positive likelihood ratio 4.21 (95% CI 2.34 to 7.58).
  • Scores for irregular and/or linear opacities were lower in the asbestosis group than in the FHP group (median 4.0 [2.0 to 8.0] vs 8.5 [6.0 to 12.0], P < 0.001). In the asbestosis group these opacities were more often in the lower lung.
  • Ground-glass opacity was more common in FHP patients, 69 (93.2%), than in asbestosis patients, 123 (60.3%) (P < 0.001).
  • Mosaic attenuation did not differ significantly: 45 asbestosis patients (22.1%) vs 15 FHP patients (20.3%), P = 0.749.
  • Forced vital capacity was lower in the asbestosis group than in the FHP group (74.36 ± 20.44 vs 85.99 ± 21.80 % predicted, P < 0.001).
  • Agreement between the two image readers was good for classifying UIP, NSIP and unclassifiable IP patterns.
• The authors' conclusion: The authors concluded that subpleural dots and diaphragmatic pleural abnormalities can distinguish asbestosis from FHP to a certain extent.
• Limitations the authors state:
  • The study was single-center and retrospective, which may have introduced selection bias.
  • The small sample size, and the few patients with some imaging patterns, may have affected the statistical results.
  • Asbestosis was compared only with FHP, not with other occupational interstitial lung diseases.
  • Cumulative exposure was represented only by duration of exposure, and no field monitoring data were available for the chrysotile-exposed patients.

Topics

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

Medical terms in this study, explained in our Lexicon: Pneumonitis, High-Resolution CT (HRCT), Diffuse Pleural Thickening, Rounded Atelectasis, Pleura, Honeycombing, Pleural Calcification.

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