Specificity of high-resolution CT findings in pulmonary asbestosis: do patients scanned for other indications have similar findings?

Our plain-English summary of Specificity of high-resolution CT findings in pulmonary asbestosis: do patients scanned for other indications have similar findings?, by C.J. Bergin, R.A. Castellino, N. Blank, et al (AJR. American Journal of Roentgenology, 1994).

The study

• Authors: C.J. Bergin, R.A. Castellino, N. Blank, L. Moses
• Journal: AJR. American Journal of Roentgenology
• Published: 1994;163(3):551-5
• Cited by: 16 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: High-resolution CT findings in patients with asbestosis include subpleural curvilinear densities, subpleural density in dependent portions of the lung, parenchymal bands, thickened septal lines, and honeycomb lung. Our objective was to examine the prevalence of these CT findings in a random group of patients scanned for a variety of clinical reasons not specifically related to occupational exposure.

Materials And Methods: One hundred sixty-eight CT studies of the thorax were performed at six levels in 168 patients examined for a variety of clinical indications. The scans were evaluated by two radiologists for the presence of subpleural curvilinear densities, subpleural density in dependent locations, parenchymal bands, thickened septal lines, and honeycomb lung.

Results: CT scans of 11 patients showed pleural plaques suggesting previous exposure to asbestos. Among the 157 studies showing no evidence of pleural plaques, CT scans showed subpleural curvilinear densities in dependent areas in 32 (20%); subpleural curvilinear densities in nondependent areas in 19 (12%); parenchymal bands in 47 (30%); thickened septal lines in dependent areas in 93 (59%), and septal lines in nondependent areas in 67 (43%); subpleural density in dependent areas in 66 (42%); and honeycomb lung in five (3%).

Conclusion: Subpleural curvilinear densities, subpleural density in dependent locations, parenchymal bands, and thickened septal lines occur as isolated and as combined CT findings in patients with a variety of underlying diseases or conditions unrelated to asbestosis and by themselves are nonspecific findings. Their occurrence, even in patients with CT evidence of pleural plaques, does not necessarily indicate the presence of asbestosis.

In plain English

This retrospective review asked how often high-resolution CT (HRCT) lung findings linked to asbestosis appear in people scanned for other reasons. Extra HRCT images were added to chest CT exams of patients referred for various reasons between June 1989 and July 1990. Two radiologists unaware of patients' histories reviewed 168 usable studies. Eleven patients had pleural plaques suggesting past asbestos exposure. Among the 157 without plaques, scans showed subpleural curvilinear densities in dependent areas in 32 (20%), parenchymal bands in 47 (30%), thickened septal lines in dependent areas in 93 (59%), subpleural density in dependent locations in 66 (42%), and honeycomb lung in five (3%). In the 11 patients with plaques, rates of the first four findings did not differ significantly from those in patients without plaques. Honeycomb lung was too rare for meaningful statistical analysis. The authors concluded that those four findings, by themselves, are nonspecific. They noted three limitations. Readers may judge these features differently. They lacked enough demographic information to examine how factors such as age, smoking history and occupational exposure influenced the findings. Their patients were not a healthy working population.

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 of chest HRCT scans, measuring how common each finding was. Two radiologists reviewed the scans without knowing the clinical histories and decided each finding by consensus. Groups were compared using chi-square analysis.
• Who was studied: 168 HRCT studies from 168 patients aged 25-94 years (mean 55), referred for chest CT for a variety of reasons between June 1989 and July 1990; 10 of 178 available studies were excluded because of motion. The patients were placed in four groups. Group 1 (85) had diffuse lung disease, drug toxicity, COPD, heart failure, or lymphoma or lung cancer follow-up. Group 2 (56) was scanned for reasons not related to diffuse lung disease. Group 3 (16) had suspected lung infection. Group 4 (11) had pleural plaques. The authors were affiliated with Stanford University School of Medicine.
• Exposure: Asbestos exposure was not directly measured. No fiber types, jobs or doses are given. Eleven patients had pleural plaques, found as incidental findings, that the authors described as suggestive of previous asbestos exposure.
• Main results:
  • Among the 157 studies with no pleural plaques, subpleural curvilinear densities in dependent areas were seen in 32 (20%).
  • Among the 157 studies with no pleural plaques, subpleural curvilinear densities in nondependent locations were seen in 19 (12%).
  • Among the 157 studies with no pleural plaques, parenchymal bands were seen in 47 (30%).
  • Among the 157 studies with no pleural plaques, thickened septal lines were seen in dependent areas in 93 (59%) and in nondependent areas in 67 (43%).
  • Among the 157 studies with no pleural plaques, subpleural density in dependent locations was seen in 66 (42%).
  • Honeycomb lung was uncommon. It was seen in four patients (5%) in group 1 and one patient (2%) in group 2.
  • There were no significant differences between the four groups in subpleural curvilinear densities or subpleural density in dependent locations (p greater than .1).
  • Parenchymal bands were most common in group 3, the patients scanned for suspected lung infection (p less than .005).
  • Septal lines, in both dependent and nondependent locations, occurred in all groups at similar rates (p greater than .1).
  • In the 11 patients with pleural plaques, the prevalence of subpleural curvilinear densities, subpleural density in dependent locations, parenchymal bands and thickened septal lines was not significantly different from that in patients without plaques.
• The authors' conclusion: The authors concluded that subpleural curvilinear densities, subpleural density in dependent locations, parenchymal bands and thickened septal lines occur, alone and in combination, in patients with many diseases or conditions unrelated to asbestosis. By themselves, these four findings are nonspecific.
• Limitations the authors state:
  • The HRCT features are defined in descriptive terms, so different readers, or the same reader at different times, may judge them differently.
  • The review lacked the demographic information needed to examine the influence of factors such as age, smoking history and occupational exposure.
  • The patients were scanned because of suspected or known medical problems, so they do not reflect a healthy working population.
  • Too few patients had honeycomb lung for meaningful statistical analysis.

Topics

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

Medical terms in this study, explained in our Lexicon: High-Resolution CT (HRCT), Asbestosis, Occupational Exposure, Thorax, CT Scan, Pleural Plaques.

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• Asbestos-related focal lung masses: manifestations on conventional and high-resolution CT scans — D.A. Lynch, G. Gamsu, et al. (1988)
• Why is high resolution computerized tomography scanning used in evaluating the lungs? — W.A. Graves, J.D. Collins, et al. (1989)
• Asbestosis: high-resolution CT-pathologic correlation — M. Akira, S. Yamamoto, et al. (1990)

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