Imaging in pleural mesothelioma: A review of the 13th International Conference of the International Mesothelioma Interest Group

Our plain-English summary of Imaging in pleural mesothelioma: A review of the 13th International Conference of the International Mesothelioma Interest Group, by S.G. Armato, K.G. Blyth, J.J. Keating, et al (Lung Cancer, 2016).

The study

• Authors: S.G. Armato, K.G. Blyth, J.J. Keating, S. Katz, S. Tsim, J. Coolen, E. Gudmundsson, I. Opitz, A.K. Nowak
• Journal: Lung Cancer
• Published: 2016;101:48-58
• Type of article: Review
• Cited by: 31 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Imaging plays an important role in the detection, diagnosis, staging, response assessment, and surveillance of malignant pleural mesothelioma. The etiology, biology, and growth pattern of mesothelioma present unique challenges for each modality used to capture various aspects of this disease. Clinical implementation of imaging techniques and information derived from images continue to evolve based on active research in this field worldwide. This paper summarizes the imaging-based research presented orally at the 2016 International Conference of the International Mesothelioma Interest Group (iMig) in Birmingham, United Kingdom, held May 1-4, 2016. Presented topics included intraoperative near-infrared imaging of mesothelioma to aid the assessment of resection completeness, an evaluation of tumor enhancement improvement with increased time delay between contrast injection and image acquisition in standard clinical magnetic resonance imaging (MRI) scans, the potential of early contrast enhancement analysis to provide MRI with a role in mesothelioma detection, the differentiation of short- and long-term survivors based on MRI tumor volume and histogram analysis, the response-assessment potential of hemodynamic parameters derived from dynamic contrast-enhanced computed tomography (DCE-CT) scans, the correlation of CT-based tumor volume with post-surgical tumor specimen weight, and consideration of the need to update the mesothelioma tumor response assessment paradigm.

Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

In plain English

This article reviewed imaging research on malignant pleural mesothelioma presented at the 2016 International Mesothelioma Interest Group conference in Birmingham, United Kingdom. In a pilot trial, Keating and colleagues injected a near-infrared dye before surgery and found leftover tumor in all eight patients after removal was thought complete. Katz and colleagues analyzed MRI scans of 10 patients. They estimated that peak tumor enhancement came 280 seconds after contrast injection, later than the conventional 40 to 60 seconds. Tsim and colleagues studied 24 patients with suspected mesothelioma, 18 of whom had a history of asbestos exposure. The first six patients helped develop the MRI protocol. Among the next 18, an MRI early-enhancement sign showed 91% sensitivity and 86% specificity for pleural malignancy. Coolen and colleagues linked higher baseline tumor volume with shorter overall survival in 15 patients on chemotherapy. Gudmundsson and colleagues found that changes in CT blood-flow measures over about two months did not differ statistically significantly between 8 treated and 8 observed patients. Opitz and colleagues found only moderate correlation between CT tumor volume and resected tumor weight in 28 patients. The presenters called for larger studies.

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 summarizing imaging research presented at a scientific conference: several small studies from different research groups, plus a discussion of revising tumor response criteria
• Who was studied: Patients with malignant pleural mesothelioma or suspected mesothelioma in six separate small studies: 8 (near-infrared surgery imaging), 10 (delayed MRI), 24 (early-enhancement MRI, of whom the first 6 were used for protocol development and 18 had complete scans), 15 (diffusion MRI during chemotherapy), 16 (dynamic CT) and 28 (CT volume versus tumor weight)
• Exposure: Asbestos exposure was not the subject of the review. The studies evaluated imaging methods: near-infrared imaging with indocyanine green, contrast-enhanced and diffusion-weighted MRI, dynamic contrast-enhanced CT, and CT-based tumor volume. In the early-enhancement MRI study, 18 of 24 patients had a history of asbestos exposure.
• Main results:
  • Near-infrared imaging study (8 patients with epithelial malignant pleural mesothelioma): after what was thought to be complete tumor removal, residual disease was found in all eight patients. The extra tissue removed was confirmed as mesothelioma in all cases.
  • Delayed MRI study (10 patients): peak tumor enhancement was estimated to occur 280 seconds after intravenous contrast, later than the conventional 40 to 60 second delay.
  • Early contrast enhancement MRI pilot study (the 18 patients with complete MRI scans, out of 24 with suspected mesothelioma): as a sign of pleural malignancy, early enhancement had sensitivity 91%, specificity 86%, positive predictive value 91% and negative predictive value 85%.
  • Diffusion-weighted MRI study (15 patients with inoperable mesothelioma on cisplatin-pemetrexed chemotherapy): higher baseline tumor volume was associated with shorter overall survival (p = 0.009, threshold 772 ml).
  • Dynamic contrast-enhanced CT study (16 patients, 8 on treatment and 8 on observation, two scans about two months apart): changes in blood-flow (hemodynamic) measures between scans did not differ significantly between the groups for any parameter. Patients on treatment showed mean relative decreases in blood volume (14.2%) and perfusion (17.2%).
  • CT volume study (28 patients undergoing pleurectomy/decortication): moderate correlation between CT-based tumor volume and resected tumor weight (correlation coefficient 0.47, p = 0.01).
• The authors' conclusion: The authors concluded that intraoperative optical imaging could become a tool to help surgeons achieve macroscopic complete resection. They noted that MRI and CT contrast methods continue to be investigated, and that CT-based tumor volume shows only moderate correlation with physical tumor weight and volume. They also considered a revised 'modified RECIST 1.1' warranted.
• Limitations the authors state:
  • For the near-infrared imaging study, a larger trial is needed to assess the impact on patient survival.
  • For the early contrast enhancement MRI pilot, a larger study is needed to define its performance against existing approaches.
  • The diffusion-weighted MRI data were preliminary and need confirmation in a larger, preferably multicenter, cohort.
  • In the CT volume study, resected tumor weight included structures other than tumor. The independent effect of the variables on survival could not be assessed.

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, Staging, Etiology, IMIG.

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