Computed tomography in pulmonary asbestosis

Our plain-English summary of Computed tomography in pulmonary asbestosis, by D. Katz, L. Kreel (Clinical Radiology, 1979).

The study

• Authors: D. Katz, L. Kreel
• Journal: Clinical Radiology
• Published: 1979;30(2):207-13
• Cited by: 64 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 002085).

Abstract

Attention is drawn to the signs of asbestosis on computed axial tomography and comparison made with findings in conventional radiology in 36 patients. CT was found to be significantly more sensitive in the detection of both pleural and parenchymal disease apart from thickened fissures. A possible sign of early mesothelioma is mentioned and an encasing variety of pleural thickening described. Perfusion changes which may represent a 'pre-radiological' interstitial fibrosis are discussed.

In plain English

This study, from the Clinical Research Centre and Northwick Park Hospital in Harrow, Middlesex, compared chest computed tomography (CT) scans with conventional chest X-rays in 36 patients. Thirty-five reported exposure to asbestos dust for three months to 40 years. One reported no exposure but had X-rays considered typical of asbestosis. Abnormal pleural thickening was seen in 27 patients on CT and 24 on X-ray. Lung (parenchymal) disease was seen in 12 on CT and six on X-ray. CT showed more plaque calcification, mediastinal pleural involvement and diaphragm irregularity. X-rays showed more thickening of the lung fissures (10 cases versus six). In five patients CT showed irregular plaque edges, which the authors said could suggest possible early mesothelioma. Only one of these had been followed up, with no change. In two patients without other signs of fibrosis, CT showed a lost normal blood-flow pattern, which the authors said raised the possibility of earlier diagnosis. The authors did not recommend routine CT but said that in doubtful cases, especially regarding compensation, it can show small plaques and earlier interstitial 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: Case series comparing CT findings with conventional chest radiograph findings in the same patients; no statistical tests are reported in the text
• Who was studied: 36 patients examined at the Division of Radiology, Clinical Research Centre, and Northwick Park Hospital, Harrow, Middlesex. Thirty-five gave a history of asbestos dust exposure. One gave no history of exposure but was included because his plain X-rays were considered typical of asbestosis. Dates of the study are not given.
• Exposure: Exposure to asbestos dust for periods of three months to 40 years. Fiber types, products and jobs are not stated.
• Main results:
  • Abnormal pleural thickening was seen in 27 of 36 patients (75%) on CT and in 24 of 36 (66%) on chest radiograph.
  • Parenchymal (interstitial) disease was seen in 12 of 36 patients (33%) on CT and in six (given as 16% in the results text and 17% in Table 4) on radiographs.
  • Calcification within plaques was seen in nine cases on CT and six on plain radiographs.
  • Mediastinal pleural involvement was seen in 11 cases on CT and four on radiography. Diaphragmatic irregularities were seen in 11 on CT and eight on radiography.
  • Fissural thickening was the one finding seen more often on plain radiographs: 10 cases on radiography versus six on CT.
  • Among patients with abnormal plaques, plaques appeared more extensive on CT in 15 (55%) and more extensive on plain radiographs in three (11%).
  • A paravertebral component of pleural thickening was seen on CT in 26 (97%) of the abnormal cases, compared with 13 (48%) on plain radiographs.
  • Irregularity of the smooth contour of pleural plaques was noted in five cases on CT and was not commented on in the radiographs. The authors said this could suggest possible early transformation into mesothelioma.
  • Circumferential pleural thickening encasing the lung was seen in seven cases on CT, and could also be interpreted as such on radiography.
  • Unilateral interstitial disease was recorded in seven cases (18%) on CT and in one case (3%) on plain X-rays. Bilateral disease was seen in five cases (14%) with both methods.
  • Loss of the normal gravity-dependent perfusion of the lungs was seen on CT in four cases with interstitial disease, and in two cases with no other evidence of interstitial fibrosis.
• The authors' conclusion: The authors did not recommend routine CT for the radiological diagnosis of asbestosis. They said that in cases of doubt, especially regarding compensation, CT can show definite but small pleural plaques, earlier interstitial disease, and circumferential encasement indicating restrictive lung disease.
• Limitations the authors state:
  • Interpreting diaphragm abnormalities on CT can be difficult because the diaphragm may be only partly seen on a given slice (partial volume effect).
  • Only one patient with plaque irregularity had annual follow-up so far, and the repeat scan showed no change. The possible link to early mesothelioma was therefore unconfirmed.
  • The reason for the loss of gravity-dependent perfusion was unknown.
  • The significance of a thin, denser line on the inner side of plaques was uncertain.

Topics

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

Medical terms in this study, explained in our Lexicon: Asbestosis, Mesothelioma, Pleural Thickening, Interstitial Fibrosis.

Related studies

• The comparison of high-resolution computed tomography findings in asbestosis and idiopathic pulmonary fibrosis — M. Akira, K. Morinaga (2016)
• Pleural calcification in pancreatitis demonstrated by computed tomography — G.M. Bydder, L. Kreel (1981)
• Computer tomography in the evaluation of pulmonary asbestosis. Preliminary experiences with the EMI general purpose scanner — L. Kreel (1976)
• The usefulness of computed tomography in detecting asbestos-related pleural abnormalities in people who had indeterminate chest radiographs: the Libby, MT, experience — O.I. Muravov, W.E. Kaye, et al. (2005)
• 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)
• Computed tomography in the early detection of asbestosis — R. Bégin, G. Ostiguy, et al. (1993)

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