Whole-Body MRI: Comparison of Its Capability for TNM Staging of Malignant Pleural Mesothelioma With That of Coregistered PET/MRI, Integrated FDG PET/CT, and Conventional Imaging

Our plain-English summary of Whole-Body MRI: Comparison of Its Capability for TNM Staging of Malignant Pleural Mesothelioma With That of Coregistered PET/MRI, Integrated FDG PET/CT, and Conventional Imaging, by Y. Ohno, M. Yui, K. Aoyagi, et al (AJR. American Journal of Roentgenology, 2019).

The study

• Authors: Y. Ohno, M. Yui, K. Aoyagi, Y. Kishida, S. Seki, H. Koyama, T. Yoshikawa
• Journal: AJR. American Journal of Roentgenology
• Published: 2019;212(2):311-319
• Cited by: 20 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: The purpose of this study was to compare the diagnostic accuracy of whole-body MRI, coregistered FDG PET/MRI, integrated FDG PET/CT, and conventional imaging examination including bone scintigraphy, contrast-enhanced brain MRI, and CT for malignant pleural mesothelioma (MPM) staging according to the new International Association for the Study of Lung Cancer (IASLC) system.

Subjects And Methods: The study subjects were 23 consecutively registered patients with MPM (15 men, eight women; mean age, 68 years for both sexes) who had prospectively undergone whole-body FDG PET/CT, whole-body MRI, conventional radiologic examination, surgical or conventional treatments, pathologic examination, and follow-up conventional imaging examinations between January 2011 and December 2017. TNM staging was evaluated by two independent readers. Kappa statistics and chi-square tests were used for evaluation agreements on each factor and clinical stage between each method and final diagnosis. The diagnostic accuracy of each method was statistically compared by use of McNemar test.

Results: The kappa values for each factor between each method and final diagnosis were significant (p < 0.0001) and ranged between 0.33 and 0.91. Kappa values between final diagnosis and stage evaluation were also significant (p < 0.0001) and ranged between 0.57 and 0.91. The diagnostic accuracy of N and stage assessment of whole-body MRI and FDG PET/MRI was significantly higher than that of conventional imaging examination (N factor, p < 0.05; stage, p < 0.05).

Conclusion: The diagnostic accuracy of whole-body MRI, FDG PET/MRI, and FDG PET/CT for TNM stage assessment based on the new IASLC MPM staging system is greater than that of conventional imaging examination.

In plain English

This study compared four imaging methods for staging malignant pleural mesothelioma under the 8th edition of the IASLC staging system. These were whole-body MRI, FDG PET/MRI (PET and MRI images combined by software), FDG PET/CT, and conventional imaging (CT, brain MRI, bone scans). Twenty-three consecutive patients with pathologically proven pleural mesothelioma (15 men, eight women, mean age 68) were enrolled in 2011 to 2017. All had a history of asbestos exposure, 21 of them occupational. Two radiologists read all images. For lymph node staging, whole-body MRI and PET/MRI with signal intensity assessment were each correct in 87.0% (20/23) of patients, conventional imaging in 56.5% (13/23), and PET/MRI without that assessment in 73.9% (17/23). For overall stage, those two approaches were again correct in 87.0% (20/23), against 56.5% (13/23). These differences from conventional imaging were statistically significant. Differences for the primary tumor and distant spread were not statistically significant. The authors concluded that whole-body MRI, FDG PET/MRI and FDG PET/CT were more accurate than conventional imaging. They noted the small sample and that treatment decisions and outcomes were not assessed.

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: Diagnostic accuracy study comparing whole-body MRI, FDG PET/MRI with and without signal intensity assessment, FDG PET/CT and conventional imaging for staging, with images read by two radiologists
• Who was studied: 23 consecutively registered patients with pathologically proven malignant pleural mesothelioma: 15 men (mean age 68, range 55 to 75) and eight women (mean age 68, range 59 to 74), enrolled between January 2011 and December 2017
• Exposure: The study examined imaging methods, not asbestos exposure. All patients had a history of asbestos exposure: occupational (21), neighborhood (1) and home (1). No fiber types, jobs or doses were given.
• Main results:
  • Lymph node (N) staging was correct in 87.0% (20/23) of patients for whole-body MRI and for FDG PET/MRI with signal intensity assessment, and in 56.5% (13/23) for conventional imaging (p = 0.02)
  • For lymph node (N) staging, FDG PET/MRI without signal intensity assessment and FDG PET/CT were each correct in 73.9% (17/23) of patients
  • Overall stage was correct in 87.0% (20/23) of patients for whole-body MRI and for FDG PET/MRI with signal intensity assessment, and in 56.5% (13/23) for conventional imaging (p = 0.02)
  • For overall stage, FDG PET/CT and FDG PET/MRI without signal intensity assessment were each correct in 69.6% (16/23) of patients
  • There were no statistically significant differences among the methods in accuracy for primary tumor (T) staging
  • There were no statistically significant differences among the methods in accuracy for distant metastasis (M) staging
  • Reading conventional imaging took significantly longer than reading whole-body MRI
• The authors' conclusion: The authors concluded that whole-body MRI, FDG PET/MRI and FDG PET/CT are more accurate than conventional imaging for TNM staging under the new IASLC mesothelioma staging system
• Limitations the authors state:
  • The study population was small
  • Statistically significant differences were found only for N factor and stage, and only between conventional imaging and whole-body MRI or FDG PET/MRI
  • Clinical outcomes, treatment decisions and the added value of MRI information were not assessed
  • PET/MRI was created by combining separately acquired images with software, not with a fully integrated PET/MRI system
  • Agreement of each reader with themselves (intraobserver agreement) was not assessed
  • Only experienced radiologists read the images
  • Unenhanced PET/CT was assessed, so the accuracy of PET/CT may have been underestimated
  • Cost-effectiveness was not compared

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: TNM Staging, Pleural Mesothelioma, Staging, Lung Cancer, IASLC.

Related studies

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• Diagnostic accuracy of sequential co-registered PET+MR in comparison to PET/CT in local thoracic staging of malignant pleural mesothelioma — K. Martini, A. Meier, et al. (2016)
• Integrated positron emission tomography-computed tomography does not accurately stage intrathoracic disease of patients undergoing trimodality therapy for malignant pleural mesothelioma — J. Pilling, J.A. Dartnell, et al. (2010)
• Volume-based parameter of 18)F-FDG PET/CT in malignant pleural mesothelioma: prediction of therapeutic response and prognostic implications — H.Y. Lee, S.H. Hyun, et al. (2010)
• Loco-regional staging of malignant pleural mesothelioma by integrated 18F-FDG PET/MRI — D.J. Murphy, S.M. Mak, et al. (2019)
• The association of 18F-FDG PET/CT parameters with survival in malignant pleural mesothelioma — A. Klabatsa, S. Chicklore, et al. (2014)

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