Why is high resolution computerized tomography scanning used in evaluating the lungs?

Our plain-English summary of Why is high resolution computerized tomography scanning used in evaluating the lungs?, by W.A. Graves, J.D. Collins, T.Q. Miller (Journal of the National Medical Association, 1989).

The study

• Authors: W.A. Graves, J.D. Collins, T.Q. Miller
• Journal: Journal of the National Medical Association
• Published: 1989;81(10):1041-6
• Type of article: Review
• Read it: PubMed · Free full text
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000086).

Abstract

High resolution computerized tomography scans have been used for medical and legal purposes to evaluate patients with a history of exposure to asbestos. Some investigators argue that high resolution scanning provides a better image of the lungs than routine computerized tomography. A review of the literature shows that although high resolution scanning displays the lymphatics in the lung, it offers no new useful diagnostic information. The authors conclude that no real advantage is attained with high resolution scanning of the lung and that pathology of disease can be determined decisively only by histology.

In plain English

This article reviewed published literature on high resolution computerized tomography (HRCT) of the lungs, a thin-slice CT technique. The authors noted that HRCT had been used for medical and legal purposes to evaluate people with a history of asbestos exposure. They compared HRCT with conventional CT and chest radiographs across interstitial, pleural, alveolar and destructive lung diseases. For interstitial disease, they reported that HRCT images did not correlate closely with pathologic findings. They described a 20-patient study of centrilobular emphysema in which HRCT correlated well with pathology, though in many of its cases only pathologic specimens were studied. They wrote that subpleural curvilinear shadows described as characteristic of asbestosis on HRCT may simply be the normal subpleural lymphatic network. They stated that two studies showed pleural thickening well on conventional CT. They added that the CT dose index for HRCT slices is three times that for conventional CT. They judged HRCT more sensitive but deficient in specificity. The authors concluded that definitive diagnosis requires pathologic specimens and that HRCT is difficult to justify other than experimentally. They noted that most reviewed studies were retrospective.

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: Literature review
• Who was studied: Published studies of HRCT of the lung, including its use to evaluate patients with a history of asbestos exposure. The article does not say how many studies were reviewed or how they were selected.
• Exposure: Not an exposure study. The article discusses imaging of asbestos-related pleural and interstitial disease alongside other lung diseases. No fiber types or doses are given.
• Main results:
  • In the section on interstitial disease (Table 1), the authors reported that HRCT images did not correlate closely with pathologic findings.
  • In a reviewed study of centrilobular emphysema, HRCT findings correlated well with pathologic findings, particularly in mild disease. The authors noted problems with that study: its small size (20 patients), and the fact that in many of the cases only pathologic specimens were studied.
  • Subpleural curvilinear shadows or linear densities described as characteristic of asbestosis on HRCT may be the normal subpleural lymphatic network.
  • The authors wrote that two studies document how well pleural thickening is displayed on conventional CT.
  • Because radiographs and conventional CT cost less and give less radiation, the authors found HRCT for screening or diagnosing suspected pleural involvement difficult to justify.
  • The CT dose index for HRCT slices is three times higher than for conventional CT.
  • The authors judged HRCT more sensitive than conventional methods but deficient in specificity.
  • The authors stated that three recent court rulings had been influenced by the insistence that HRCT can describe pleural changes highly characteristic of asbestosis.
• The authors' conclusion: The authors concluded that pathologic specimens are needed for definitive diagnosis of lung parenchymal disease. Given HRCT's lack of specificity, higher radiation exposure and higher expense, they concluded its use is difficult to justify other than in an experimental capacity.
• Limitations the authors state:
  • Most of the studies reviewed were retrospective, and many used frozen fixed lung specimens.

Topics

Medical terms in this study, explained in our Lexicon: Pathology, Histology.

Related studies

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• Yield of Low-Dose Computerized Tomography Screening for Lung Cancer in High-Risk Workers: The Case of 7189 US Nuclear Weapons Workers — S.B. Markowitz, A. Manowitz, et al. (2018)
• 18-FDG positron emission tomography in the evaluation of malignant pleural diseases - a pilot study — A. Carretta, C. Landoni, et al. (2000)
• Asbestos-related focal lung masses: manifestations on conventional and high-resolution CT scans — D.A. Lynch, G. Gamsu, et al. (1988)
• 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)
• High resolution computed tomography and lung function in asbestos-exposed workers with normal chest radiographs — C.A. Staples, G. Gamsu, et al. (1989)

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