The role of imaging in malignant pleural mesothelioma: an update after the 2018 BTS guidelines

Our plain-English summary of The role of imaging in malignant pleural mesothelioma: an update after the 2018 BTS guidelines, by S. Sinha, A.J. Swift, M.A. Kamil, et al (Clinical Radiology, 2020).

The study

• Authors: S. Sinha, A.J. Swift, M.A. Kamil, S. Matthews, M.J. Bull, P. Fisher, D. De Fonseka, S. Saha, J.G. Edwards, C.S. Johns
• Journal: Clinical Radiology
• Published: 2020;75(6):423-432
• Type of article: Review
• Cited by: 17 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Malignant pleural mesothelioma (MPM) is a primary malignancy of the pleura and is associated with a poor outcome. The symptoms and signs of malignant mesothelioma present late in the natural history of the disease and are non-specific, making the diagnosis challenging and imaging key. In 2018, the British Thoracic Society (BTS) updated the guideline on diagnosis, staging, and follow-up of patients with MPM. These recommendations are discussed in this review of the current literature on imaging of MPM. It is estimated MPM will continue to cause serious morbidity and mortality in the UK late into the 21st century, and internationally, people continue to be exposed to asbestos. We aim to update the reader on current and future imaging strategies, which could aid early diagnosis of pleural malignancy and provide an update on staging and assessment of tumour response.

Crown Copyright © 2019. Published by Elsevier Ltd. All rights reserved.

In plain English

This article reviewed published research on imaging in malignant pleural mesothelioma. Its authors, from Sheffield Teaching Hospitals, UK, discussed it alongside the British Thoracic Society's 2018 guideline; it reported no new patient study, though it showed example scans from patients. Following the guideline, it described a chest X-ray first for suggestive symptoms, urgent referral if the X-ray looked suspicious, and possible further imaging despite a normal X-ray for persistent symptoms with past asbestos exposure. Contrast-enhanced CT optimised for the pleura was the first-line cross-sectional scan, coming after the X-ray. PET-CT and MRI were for selected patients, with PET-CT used cautiously because talc pleurodesis can cause false positives. Citing earlier studies, the authors wrote that mesothelioma's CT features appear relatively late. They wrote that CT identifies central-chest lymph nodes poorly (sensitivity 60%, specificity 70%) and that pleural plaques mark asbestos exposure but are not pre-malignant. The authors concluded that non-invasive tests remain relatively limited for diagnosing mesothelioma and that contrast-enhanced CT is the imaging mainstay. They added that whether MRI and PET add value is unclear, and their roles are not yet fully validated prospectively.

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: Narrative review of the literature on imaging of malignant pleural mesothelioma, discussed in light of the 2018 British Thoracic Society (BTS) guideline
• Who was studied: No new group of patients was studied. The authors reviewed published literature and guideline recommendations, illustrated with example scans from patients. They are radiology, oncology, respiratory medicine and thoracic surgery staff at Sheffield Teaching Hospitals, UK.
• Exposure: This is not an exposure study; it deals with imaging tests (chest radiography, CT, PET-CT, MRI, ultrasound). As background, the article states that exposure to asbestos is mostly occupational or passive, from washing the clothes of people who work with asbestos. It refers to 'chrysolite (white asbestos) and amphibole (blue and brown asbestos)'.
• Main results:
  • According to the review, the 2018 BTS guideline offers all patients with clinical features of mesothelioma an urgent chest X-ray as the first imaging test.
  • According to the review, patients with suspicious X-ray findings should be urgently referred for further investigation. Further imaging may be considered in patients with persistent symptoms and prior asbestos exposure.
  • According to the review, contrast-enhanced CT of the thorax is the second-line investigation after the chest X-ray. The 2018 BTS guideline makes CT optimised for the pleura the first-line cross-sectional imaging test.
  • The review states that PET-CT should be avoided after previous talc pleurodesis because of the risk of false positives.
  • The review states that pleural plaques identify asbestos exposure but are not pre-malignant. It also states that routine radiographic screening of people with plaques who have no symptoms is not advised.
  • Citing earlier studies, the review states that the CT features of mesothelioma are present relatively late in the disease.
  • Citing earlier studies, the review reports that identifying mediastinal lymph nodes on CT is difficult (sensitivity 60% and specificity 70%).
  • Citing earlier studies, the review reports that on MRI, the characteristic features combined with pleural thickness over 1 cm distinguished malignant from benign pleural disease with sensitivity 100% and specificity 95%.
  • Citing earlier studies, the review reports that the sensitivity of cytology on pleural fluid samples ranged from 16% to 73%. It also reports that image-guided pleural biopsy had sensitivity rates reported up to 94%.
  • A cited North American multicentre volumetric CT study found poor agreement between two radiologists on T stage but good agreement on tumour volume measurements.
• The authors' conclusion: The authors concluded that non-invasive tests remain relatively limited in diagnosing mesothelioma and that contrast-enhanced CT is the mainstay of imaging. In their view, it is unclear whether MRI and PET add value, and their roles are yet to be fully validated prospectively.
• Limitations the authors state:
  • The authors note that much of the literature on CT and MRI imaging of mesothelioma is now dated.
  • The authors note a lack of data on the role of imaging in the follow-up of mesothelioma.
  • The authors note that TNM staging is based on surgical staging and is hard to apply accurately to imaging.

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Pleura, Mesothelioma, Staging.

Related studies

• Commentary on pathologic diagnosis of asbestosis and critique of the 2010 Asbestosis Committee of the College of American Pathologists (CAP) and Pulmonary Pathology Society's (PPS) update on the diagnostic criteria for pathologic asbestosis — S.P. Hammar, J.L. Abraham (2015)
• Imaging of the pleura — E.J. Helm, T.N. Matin, et al. (2010)
• Development of a guideline on reading CT images of malignant pleural mesothelioma and selection of the reference CT films — H. Zhou, T. Tamura, et al. (2012)
• Divided by an ocean of water but united in an ocean of uncertainty: A transatlantic review of mesothelioma surgery guidelines — D.A. Waller, I. Opitz, et al. (2021)
• Evaluation of the efficacy of the guideline on reading CT images of malignant pleural mesothelioma with reference CT films for improving the proficiency of radiologists — H. Zhou, T. Tamura, et al. (2013)
• From the archives of the AFIP: primary peritoneal tumors: imaging features with pathologic correlation — A.D. Levy, J. Arnáiz, et al. (2008)

Browse more research in Clinical Radiology, or return to medical research.