Imaging in pleural mesothelioma: a review of the 11th International Conference of the International Mesothelioma Interest Group

Our plain-English summary of Imaging in pleural mesothelioma: a review of the 11th International Conference of the International Mesothelioma Interest Group, by S.G. Armato, Z.E. Labby, J. Coolen, et al (Lung Cancer, 2013).

The study

• Authors: S.G. Armato, Z.E. Labby, J. Coolen, A. Klabatsa, M. Feigen, T. Persigehl, R.R. Gill
• Journal: Lung Cancer
• Published: 2013;82(2):190-6
• Type of article: Review
• Cited by: 26 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Imaging of malignant pleural mesothelioma (MPM) is essential to the diagnosis, assessment, and monitoring of this disease. The complex morphology and growth pattern of MPM, however, create unique challenges for image acquisition and interpretation. These challenges have captured the attention of investigators around the world, some of whom presented their work at the 2012 International Conference of the International Mesothelioma Interest Group (iMig 2012) in Boston, Massachusetts, USA, September 2012. The measurement of tumor thickness on computed tomography (CT) scans is the current standard of care in the assessment of MPM tumor response to therapy; in this context, variability among observers in the measurement task and in the tumor response classification categories derived from such measurements was reported. Alternate CT-based tumor response criteria, specifically direct measurement of tumor volume change and change in lung volume as a surrogate for tumor response, were presented. Dynamic contrast-enhanced CT has a role in other settings, but investigation into its potential use for imaging mesothelioma tumor perfusion only recently has been initiated. Magnetic resonance imaging (MRI) and positron-emission tomography (PET) are important imaging modalities in MPM and complement the information provided by CT. The pointillism sign in diffusion-weighted MRI was reported as a potential parameter for the classification of pleural lesions as benign or malignant, and PET parameters that measure tumor activity and functional tumor volume were presented as indicators of patient prognosis. Also reported was the use of PET/CT in the management of patients who undergo high-dose radiation therapy. Imaging for MPM impacts everything from initial patient diagnosis to the outcomes of clinical trials; iMig 2012 captured this broad range of imaging applications as investigators exploit technology and implement multidisciplinary approaches toward the benefit of MPM patients.

Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

In plain English

This article was a review, not a single study. The authors summarized imaging research on malignant pleural mesothelioma (MPM) presented at the 2012 International Conference of the International Mesothelioma Interest Group in Boston. The presentations covered CT, MRI and PET. In one, physicians measured 170 tumor sites on 105 CT scans from 50 patients. At sites thinner than 7.5 mm, differences between observers' measurements reached 20% of tumor thickness, the change used to call disease progression. In 61 patients on chemotherapy, those whose lung volume shrank (n = 25) had significantly worse prognosis than those whose lung volume grew (n = 36). In 76 patients with suspicious pleural changes, a diffusion-weighted MRI pattern called the pointillism sign identified malignant disease with sensitivity of 91.7% (44 of 48). In 60 patients, higher PET values were linked to shorter survival, but no variable was significant in multivariate analysis. The authors concluded that CT-based modified RECIST guidelines remained more reliable than other tumor response approaches. The article did not discuss asbestos exposure.

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: Review of imaging studies presented at a scientific conference (iMig 2012)
• Who was studied: Patients with malignant pleural mesothelioma or suspected MPM in several separate studies presented at iMig 2012, Boston, September 2012. Study sizes ranged from 13 to 76 patients. Examples: 105 CT scans from 50 patients; 15 patients from a multi-center trial; 61 patients on chemotherapy; 76 consecutive patients with suspicious pleural abnormalities; 60 patients with pre-treatment PET/CT from January 2005 to December 2011; 27 radiotherapy patients treated from 2003 to 2012.
• Exposure: Not addressed. The article concerns imaging methods (CT, dynamic contrast-enhanced CT, MRI, PET/CT), not asbestos or fiber exposure.
• Main results:
  • Tumor thickness study (50 patients, 170 sites, five physician observers): at tumor sites with mean thickness less than 7.5 mm, the 75th percentile of interobserver variability included 20% of the tumor length.
  • Response evaluation study (15 patients, 43 examinations, two radiologists): intraobserver variability was lowest with modified RECIST. The 95% limits of agreement were minus 28.4 to 12.9 for the experienced reader and minus 84.3 to 53.6 for the less-experienced reader.
  • Lung and tumor volume study (61 chemotherapy patients, 216 CT scans): patients with lung volume loss (n = 25) had significantly worse prognosis than patients with lung volume gain (n = 36; p = 0.0003).
  • In the same study, increases in disease volume growth rate (HR = 1.32, p = 0.0003) and decreases in normalized lung volume on the affected side (HR = 0.76, p = 0.003) were each significantly associated with prognosis.
  • Dynamic contrast-enhanced CT pilot study (13 patients): no DCE-CT parameters were significantly correlated with changes in tumor burden. The perfusion parameter changed by +29% in the observation group (n = 7) and by −13% in the treatment group (n = 6).
  • MRI study (76 patients: 28 benign, 48 malignant): the pointillism sign had sensitivity 91.7% (44/48) and specificity 85.7% (24/28) for malignant pleural disease. The shrinking lung sign had sensitivity 50.0% (24/48).
  • PET study (60 patients): median overall survival was 14.1 months. Survival was lower with high total lesion glycolysis (6.4 vs. 18.1 months, p = 0.0002) and with other high PET values. None of the variables was statistically significant in multivariate analysis.
  • Radiotherapy study (27 patients, 45 to 60 Gy): 7 of 27 patients failed within the radiation field, a locoregional control rate of 74%. Median FDG reduction in 15 evaluable patients was 57% (range 14 to 99%).
• The authors' conclusion: The authors concluded that CT-based modified RECIST guidelines remained more reliable than other tumor response approaches. They added that thickness measurements show variability that could affect how minimum measurable disease is defined in future trials.
• Limitations the authors state:
  • The response evaluation findings must be confirmed in a larger group of patients with more readers and time points.
  • The lung volume approach was restricted to patients with disease on one side.
  • Further studies are needed to validate the clinical usefulness and specificity of the pointillism sign.
  • The review did not cover the role of imaging in clinical staging of MPM.

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, Mesothelioma, IMIG, Diffusion-Weighted MRI, Prognosis, Clinical Trial, Multidisciplinary Team.

Related studies

• Imaging in pleural mesothelioma: A review of the 12th International Conference of the International Mesothelioma Interest Group — S.G. Armato, J. Coolen, et al. (2015)
• Imaging in pleural mesothelioma: A review of the 14th International Conference of the International Mesothelioma Interest Group — S.G. Armato, R.J. Francis, et al. (2019)
• Imaging in pleural mesothelioma: A review of the 13th International Conference of the International Mesothelioma Interest Group — S.G. Armato, K.G. Blyth, et al. (2016)
• Imaging in pleural mesothelioma: a review of imaging research presented at the 9th International Meeting of the International Mesothelioma Interest Group — A.K. Nowak, S.G. Armato, et al. (2010)
• Molecular pathways and diagnosis in malignant mesothelioma: A review of the 14th International Conference of the International Mesothelioma Interest Group — D.B. Chapel, A. Churg, et al. (2019)
• Progress of malignant mesothelioma research in basic science: A review of the 14th international conference of the international mesothelioma interest group (iMig2018) — L. Wu, I. Dell'Anno, et al. (2019)

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