The comparison of high-resolution computed tomography findings in asbestosis and idiopathic pulmonary fibrosis

Our plain-English summary of The comparison of high-resolution computed tomography findings in asbestosis and idiopathic pulmonary fibrosis, by M. Akira, K. Morinaga (American Journal of Industrial Medicine, 2016).

The study

• Authors: M. Akira, K. Morinaga
• Journal: American Journal of Industrial Medicine
• Published: 2016;59(4):301-6
• Cited by: 19 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: To determine whether the HRCT findings are useful to differentiate asbestosis from idiopathic pulmonary fibrosis (IPF).

Methods: We assessed HRCT scans from patients with asbestosis (n = 96) and IPF (n = 65). The frequencies and extent of parenchymal abnormalities and the frequencies of pleural changes were evaluated by consensus of two chest radiologists.

Results: There was a significant difference between IPF and asbestosis in pleural changes. In addition, there were significant differences between IPF and asbestosis in several parenchymal abnormalities on CT, especially in the less advanced stage of both diseases. On multivariate analysis, HRCT features that distinguished asbestosis from IPF were subpleural lines at a distance of less than 5 mm from the inner chest wall, subpleural dots and parenchymal bands.

Conclusions: There are significant differences between IPF and asbestosis in the parenchymal and pleural abnormalities on CT.

© 2016 Wiley Periodicals, Inc.

In plain English

The authors reviewed high-resolution CT (HRCT) scans of 96 patients with asbestosis and 65 with idiopathic pulmonary fibrosis (IPF) from two Japanese referral centers, scanned between 2002 and 2012. Most asbestosis patients were textile or asbestos manufacturing workers with substantial exposure. All IPF patients had a biopsy diagnosis. Two radiologists agreed on the findings by consensus. Pleural changes appeared in 71 of 96 asbestosis patients (74%) and in 1 of 65 IPF patients (2%). Pleural plaques were seen in 69 asbestosis patients and in no IPF patient. The overall extent of lung abnormalities did not differ significantly. Honeycombing was more common in IPF, while subpleural dots, subpleural lines, parenchymal bands and mosaic attenuation were more common in asbestosis. In a multivariate analysis, three features distinguished asbestosis from IPF: subpleural lines less than 5 mm from the chest wall (odds ratio 17.68, 95% confidence interval 7.69 to 40.65), subpleural dots (12.09, 3.84 to 38.02) and parenchymal bands (12.12, 1.15 to 128.12). The authors concluded that these features, together with pleural plaques, best differentiated the two diseases. They noted that some asbestosis patients might also have had IPF.

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 review comparing HRCT scans of two patient groups (asbestosis and IPF). Two chest radiologists without clinical or pathologic information read the scans and reached consensus.
• Who was studied: 96 consecutive patients with asbestosis (62 men, 34 women; median age 67) and 65 consecutive patients with biopsy-diagnosed IPF (42 men, 23 women; median age 61). They were identified from the radiology databases of two referral centers (Kinki-chuo Chest Medical Center and Osaka Medical Center, Japan), with scans from 2002 to 2012. In 42 asbestosis patients the diagnosis was also made on pathologic grounds.
• Exposure: Substantial occupational asbestos exposure in the asbestosis group. The occupations were textile workers (48), asbestos manufacturing workers (36), asbestos spraying (7) and shipyard workers (5). Fiber types and doses were not reported.
• Main results:
  • Pleural changes were found in 71 of 96 patients with asbestosis (74%) and in 1 of 65 patients with IPF (2%).
  • Pleural plaques were seen in 69 asbestosis patients (72%) and in no IPF patient. Diffuse pleural thickening was seen in 25 asbestosis patients and in 1 IPF patient.
  • There was no significant difference between the groups in the overall extent of parenchymal abnormalities, ground glass opacities or reticular opacities. Honeycombing and traction bronchiectasis grade did differ: honeycombing was seen in 46 of 65 IPF patients (71%) and in 31 of 96 asbestosis patients (32%).
  • Some features were more common in asbestosis than in IPF: subpleural dots (90 of 96, 94%, vs 30 of 65, 46%), subpleural lines (82, 85%, vs 16, 25%), parenchymal bands (31, 32%, vs 1, 2%) and mosaic attenuation (25, 26%, vs 4, 6%).
  • In patients with the most advanced radiographic profusion (profusion 3: 11 asbestosis and 14 IPF patients), there were no significant differences in subpleural dots or honeycombing. Other differences remained, including in subpleural lines and mosaic attenuation.
  • The text reports that subpleural lines in asbestosis patients lay 2 to 3 mm from the inner chest wall. In IPF patients they lay more than 5 mm away.
  • On multivariate analysis, three features distinguished asbestosis from IPF: subpleural lines less than 5 mm from the inner chest wall (odds ratio 17.68, 95% CI 7.69 to 40.65), subpleural dots (odds ratio 12.09, 95% CI 3.84 to 38.02) and parenchymal bands (odds ratio 12.12, 95% CI 1.15 to 128.12).
  • Patients with asbestosis were older (P = 0.001). Patients with IPF had a higher radiographic profusion (P = 0.007).
• The authors' conclusion: The authors concluded that the HRCT features that best differentiated asbestosis from IPF were pleural plaques, subpleural lines less than 5 mm from the inner chest wall, subpleural dots and parenchymal bands. They noted that these features can be found in less severe areas of the lung in patients with advanced disease, and that differences were greatest in the less advanced stages of both diseases.
• Limitations the authors state:
  • Some patients clinically diagnosed with asbestosis might have had both asbestosis and IPF.
  • Including only biopsy-proved IPF patients may have introduced selection bias, because IPF patients with typical HRCT findings seldom undergo lung biopsy.
  • Scans were taken at 15 to 20 mm intervals, so small abnormalities and pleural changes may have been missed between CT sections.
  • Prone (face-down) HRCT scans, described as useful in early asbestosis, were not available for all patients.

Topics

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

Medical terms in this study, explained in our Lexicon: Idiopathic, Pulmonary Fibrosis, High-Resolution CT (HRCT), Multivariate Analysis, Subpleural Curvilinear Line.

Related studies

• 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)
• 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)
• 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)
• Diagnosis of asbestosis by a time expanded wave form analysis, auscultation and high resolution computed tomography: a comparative study — N. al Jarad, B. Strickland, et al. (1993)
• Clinical and radiological criteria for the differential diagnosis between asbestosis and idiopathic pulmonary fibrosis: Application in two cases — A. Stufano, A. Scardapane, et al. (2021)

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