Development of a guideline on reading CT images of malignant pleural mesothelioma and selection of the reference CT films

Our plain-English summary of Development of a guideline on reading CT images of malignant pleural mesothelioma and selection of the reference CT films, by H. Zhou, T. Tamura, Y. Kusaka, et al (European Journal of Radiology, 2012).

The study

• Authors: H. Zhou, T. Tamura, Y. Kusaka, N. Suganuma, P. Subhannachart, C. Vijitsanguan, W. Noisiri, K.G. Hering, M. Akira, H. Itoh, H. Arakawa, Y. Ishikawa, S. Kumagai, N. Kurumatani
• Journal: European Journal of Radiology
• Published: 2012;81(12):4203-10
• Cited by: 10 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Purpose: International experts developed a guideline on reading CT images of malignant pleural mesothelioma for radiologists and physicians. It is intended that it act as a supplement to the current International Classification of HRCT for Occupational and Environmental Respiratory Diseases.

Methods: The research literatures on mesothelioma CT features were systematically reviewed. Ten mesothelioma CT features were adopted into the guideline prepared according to experts' opinion. The terminology of mesothelioma CT features and mesothelioma probability were agreed by consensus of experts. The CT reference films for each mesothelioma feature were selected based on agreement by experts from 22 definite mesothelioma cases confirmed pathologically and immunohistochemically. To support the validity of the mesothelioma probability, 4 experts' readings of CT films from 57 cases with or without mesothelioma were analyzed by kappa statistics between the experts; sensitivity and specificity for mesothelioma were also assessed.

Results: The mesothelioma CT Guideline was developed, providing the terminology of CT features and the mesothelioma probability, the judgement of severity, the distribution of mesothelioma, and the revised CT reading sheet including mesothelioma items. The CT reference films with ten mesothelioma typical features were selected. The average linearly and quadratically weighted kappa of the agreement on the 4-point scale mesothelioma probability were 0.58 and 0.71, respectively. The average sensitivity and specificity for mesothelioma were 93.2% and 65.6%, respectively.

Conclusion: The evidence-based mesothelioma CT Guideline developed may serve as a good educational tool to facilitate physicians in recognising mesothelioma and improve their proficiency in diagnosis of mesothelioma.

Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

In plain English

This article described how international experts built a guideline for reading CT scans of malignant pleural mesothelioma. It was meant to supplement an existing international classification of high-resolution CT for occupational and environmental respiratory diseases. The authors reviewed published studies, chose ten typical CT features, and agreed at two workshops on terms and a four-grade scale of mesothelioma probability. They tested the scale on CT films of 57 cases from an investigation around a closed asbestos cement pipe factory in Amagasaki City, Japan, which had used crocidolite and chrysotile. Of these, 44 had mesothelioma. Four experts read the films without knowing the pathology results. On the probability scale, agreement between experts averaged 0.58 (linearly weighted kappa) and 0.71 (quadratically weighted kappa), and was weaker for the middle grades 2 and 3. Average sensitivity was 93.2% among the 44 mesothelioma cases, and average specificity was 65.6% among 8 non-mesothelioma cases. The authors concluded that the guideline may serve as a good educational tool. They noted that the few non-mesothelioma cases had only clinical diagnoses, which might affect the specificity result.

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: Development of a CT reading guideline, based on a literature review and expert workshops, with a reading trial in which four experts independently read CT films blinded to pathology results; agreement between readers, sensitivity and specificity were calculated
• Who was studied: CT films of 57 cases obtained by two of the authors from medical records, as of April 2007, in connection with the Kubota Plant in Amagasaki City, Hyogo Prefecture, Japan. There were 44 malignant pleural mesothelioma cases: 22 confirmed by both histopathology and immunohistochemical staining (the 'gold standard' cases), 16 by histopathology alone, and 6 by cytology. There were also 5 cases clinically diagnosed as lung cancer, 3 pleural plaque cases and 5 indefinite cases
• Exposure: Environmental asbestos exposure from a closed asbestos cement pipe factory that used crocidolite and chrysotile between 1957 and 1975, with an annual average of 4670 tons of crocidolite and 4600 tons of chrysotile. The authors stated that the mesothelioma cases were ascribed to environmental asbestos pollution, mainly crocidolite from the Kubota factory
• Main results:
  • Agreement between the four experts on the 4-point mesothelioma probability scale (57 cases): average linearly weighted kappa 0.58 plus or minus 0.06
  • All pairwise quadratically weighted kappa values for the probability scale were over 0.60, with an average of 0.71
  • Multi-reader agreement by grade: Grade 1 (negative) 0.60 and Grade 4 (high probability) 0.53, but only 0.15 for Grade 2 and 0.23 for Grade 3
  • Average sensitivity for mesothelioma, with Grade 2 or higher counted as positive, was 93.2% among the 44 mesothelioma cases; individual readers ranged from 39/44 (88.64%) to 43/44 (97.73%)
  • Average specificity, with Grade 1 counted as negative, was 65.6% among the 8 non-mesothelioma cases; individual readers ranged from 4/8 (50%) to 6/8 (75%). The 5 indefinite cases were excluded
  • Agreement on individual CT features varied. Average kappa was 0.55 for unilateral pleural effusion, 0.65 for mediastinal pleural thickening, 0.43 for interlobar fissure thickening, 0.47 for tumoral encasement of lung, 0.38 for invasion, 0.14 for nodular pleural thickening and 0.06 for diminished lung
  • Two of the 22 'gold standard' mesothelioma cases, which showed many typical features, were selected as CT reference images
• The authors' conclusion: The authors concluded that the guideline and reference CT films may serve as good tools in education, clinical practice and secondary prevention to improve radiologists' and physicians' proficiency in diagnosing malignant pleural mesothelioma
• Limitations the authors state:
  • The few non-mesothelioma cases had only clinical diagnoses, with no pathological examination records, which might affect the specificity result
  • 'Diminished lung' was a newly proposed feature that experts may have missed in the reading trial, giving a low kappa; Reader 1's sheet did not include this feature

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, High-Resolution CT (HRCT), Mesothelioma.

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