Conventional and high resolution computed tomography in the diagnosis of asbestos-related diseases

Our plain-English summary of Conventional and high resolution computed tomography in the diagnosis of asbestos-related diseases, by D.A. Lynch, G. Gamsu, D.R. Aberle (Radiographics, 1989).

The study

• Authors: D.A. Lynch, G. Gamsu, D.R. Aberle
• Journal: Radiographics
• Published: 1989;9(3):523-51
• Cited by: 66 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

High resolution CT (HRCT) can image the fine structures of the lung parenchyma and the pleura. Analysis of supine and prone HRCT scans in 300 patients with asbestos exposure shows that asbestosis is characterized the following findings; (1) parenchymal bands, (2) increased interlobular septa, (3) increased intralobular core structures, (4) subpleural lines, and (5) dependent opacity. Pleural disease is well displayed on HRCT scans. Correlated studies with whole lung sections confirm the HRCT findings. Masses in asbestosis may be benign or malignant, and CT helps in their differentiation. HRCT correlates well with radiographic and clinical criteria for asbestosis and is more sensitive than either in detecting abnormalities.

In plain English

This article was an illustrated teaching exhibit, displayed at a 1987 radiology meeting. Radiologists at the University of California, San Francisco described abnormalities seen on conventional and high resolution CT in over 300 workers with significant asbestos exposure. It had no methods section but gave some percentages from the authors' experience. It described and illustrated findings, sometimes alongside biopsy and whole-lung specimens. The authors described the CT appearance of pleural plaques, diffuse pleural thickening and asbestosis, and called benign asbestos-related effusion a diagnosis of exclusion. They stated that a face-down (prone) scan was frequently critical, because a band of opacity in the lowest part of the lung usually cleared in that position. They listed the high resolution CT features of asbestosis, stating all but two had pathologic correlates. They cautioned that these features are not specific to asbestosis, and that CT cannot distinguish mesothelioma from pleural spread of other cancer. In their experience, more than 90% of unexpected masses found on CT were benign. They concluded that CT is more sensitive, and probably more specific, than chest radiography for asbestos-related pleural disease.

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: Illustrated educational exhibit (pictorial review) based on the authors' clinical experience. It has no methods section, and it gives some percentages from the authors' experience without saying how they were counted.
• Who was studied: Over 300 workers with significant asbestos exposure seen in the Department of Radiology, University of California Medical Center, San Francisco; dates not given
• Exposure: Significant asbestos exposure; fiber types, jobs and doses for these workers are not stated
• Main results:
  • In patients with asbestosis, the opacity seen in the lowest (dependent) part of the lung occasionally persisted but usually cleared when the patient was scanned face down (prone)
  • The authors found the band of dependent subpleural opacity in only 30% of workers without evidence of lung disease; the percentage given for workers with asbestosis is unreadable in the scanned text
  • Curvilinear subpleural lines in the dependent lung were seen in about 30% of patients with asbestosis, and in an equal percentage of those without evidence of lung fibrosis
  • The authors stated that the prone high resolution CT scan is frequently critical for identifying fine abnormalities in the back of the lung
  • Of the high resolution CT features of asbestosis, all except subpleural curvilinear lines and subpleural dependent lung opacity had pathologic correlates
  • Thickening of the interlobular septa seen on high resolution CT in asbestosis was attributed to fibrosis, illustrated with an open lung biopsy specimen
  • The authors stated that benign asbestos-related pleural effusion remains a diagnosis of exclusion
  • In the authors' experience, CT finds unanticipated masses in about 10% of workers with significant asbestos exposure, and more than 90% of these are benign focal lesions
• The authors' conclusion: The authors concluded that CT is more sensitive and probably more specific than conventional chest radiography for asbestos-related pleural disease. They also concluded that high resolution CT can identify pleural plaques earlier than conventional imaging, and that CT can identify and characterize asbestos-related lung masses, most of which are not malignant.
• Limitations the authors state:
  • The CT features of asbestosis are not specific to asbestosis and may occur in other types of pulmonary fibrosis
  • CT cannot distinguish mesothelioma from pleural involvement by carcinoma
  • Persistent subpleural opacity in non-dependent lung is usually abnormal, but its exact significance is often uncertain

Topics

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

Medical terms in this study, explained in our Lexicon: High-Resolution CT (HRCT), Parenchyma, Pleura, Asbestos Exposure, Subpleural Curvilinear Line.

Related studies

• Asbestos-related focal lung masses: manifestations on conventional and high-resolution CT scans — D.A. Lynch, G. Gamsu, et al. (1988)
• High-resolution computed tomography of asbestos-related diseases — D.R. Aberle (1991)
• Computed tomography in the diagnosis of asbestos-related thoracic disease — G. Gamsu, D.R. Aberle, et al. (1989)
• High-resolution computed tomography in cases with environmental exposure to asbestos in Turkey — F. Topçu, H. Bayram, et al. (2000)
• 3-Dimensional Quantification of Composite Pleural Plaque Volume in Patients Exposed to Asbestos Using High-resolution Computed Tomography: A Validation Study — G. Dournes, A. Dubois, et al. (2019)
• 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)

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