Malignant Pleural Mesothelioma CT Imaging: How to Measure It Correctly?

Our plain-English summary of Malignant Pleural Mesothelioma CT Imaging: How to Measure It Correctly?, by C. Picone, A. Porto, R. Fusco, et al (Cancer Control, 2025).

The study

• Authors: C. Picone, A. Porto, R. Fusco, V. Granata, M.C. Brunese, A. Montanino, G. Esposito, R. Costanzo, A. Manzo, V. Sforza, C. Sandomenico, G. Palumbo, E. Mercadante, A. Ottaiano, G. Vallone, F. Caranci, R. Mormile, A. Morabito, A. Petrillo
• Journal: Cancer Control
• Published: 2025;32:10732748241301901
• Type of article: Review
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Malignant pleural mesothelioma is the most common primary tumor of the pleura. The unique growth pattern of malignant pleural mesothelioma makes it difficult to apply the Response Evaluation Criteria for Solid Tumors (RECIST). Hence the need to use modified RECIST (mRECIST) criteria, as they better fit the unique growth pattern of malignant pleural mesothelioma. The thickness of the tumor perpendicular to the chest wall or mediastinum is measured at 2 points at 3 separate levels at least 1 cm apart on chest CT scans, and summed to obtain a one-dimensional pleural measurement. The same criterion has also been used to assess response to treatment. RECIST 1.1 represents a further update, taking into account new concepts such as revised minimum dimensions for lymph nodes and an approach to lesions that become non-measurable. Based on experience and published literature, the hypothesis of merging the 2 above-mentioned criteria in mRECIST 1.1 for mesothelioma and the use of iRECIST for the application to immune-based therapies (iRECIST) was considered. Purpose: Support the importance of studying pleural mesothelioma in a reliable and reproducible way, through a scrupulous methodology, applying the mRECIST1.1 and iRECIST criteria. Conclusions: Adoption of a standardized study metodology can make the study of PM reproducible and correct.

In plain English

This mini review described how to measure malignant pleural mesothelioma, a tumor of the lining around the lungs, on computed tomography (CT) scans. In their introduction, the authors noted that this tumor is strongly associated with occupational asbestos exposure. The review presented no new study results. It summarized published measurement rules and showed example CT images. Because this tumor typically grows as a layer around the pleura rather than as round lumps, the review described the modified RECIST (mRECIST) method. Tumor thickness is measured perpendicular to the chest wall or mediastinum, at 2 locations on each of 3 levels at least 1 cm apart, and the 6 measurements are added up. The newer mRECIST 1.1 recommends lowering the smallest measurable thickness from 10 mm to 7 mm. It also described iRECIST, used in immunotherapy trials, where inflammation around the tumor can look like tumor growth. It summarized recommended scan methods, including thin image slices in 3 planes and intravenous contrast. The authors concluded that only a standardized method can make the study of pleural mesothelioma reproducible and correct.

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: Mini review (narrative review of CT measurement and response criteria for malignant pleural mesothelioma, illustrated with example images)
• Who was studied: No study population was analyzed. Anonymized CT images of patients with malignant pleural mesothelioma were used as illustrations; the number of patients is not given.
• Exposure: No exposure was studied; the review concerns CT measurement methods. As background, the introduction states that malignant pleural mesothelioma is strongly associated with occupational asbestos exposure. No fiber types are named.
• Main results:
  • The review described mRECIST as measuring tumor thickness perpendicular to the chest wall or mediastinum.
  • mRECIST uses 6 measurement sites, at 2 locations on each of 3 levels on axial CT slices at least 1 cm apart, and the 6 measurements are added to give a total.
  • The review described mRECIST 1.1 as recommending that the minimally measurable disease for mesothelioma be reduced from 10 mm to 7 mm.
  • The review reported the iMIG Pleural Imaging Expert Panel recommendation to read CT images in 3 planes, with slices of about 1-2 mm in the axial plane and 2-3 mm in the sagittal and coronal planes.
  • Measurement sites are preferably chosen over the left atrium and under the aortic arch, to try to standardize reproducibility.
  • The review stated that intravenous iodinated contrast is essential for detecting and quantifying tumor deposits on CT.
  • The review stated that pleural thickening greater than 1 cm in a nodular, lobular or circumferential pattern on contrast-enhanced CT is highly suggestive of pleural mesothelioma.
  • Mediastinal lymph nodes with a short axis of 10 mm or more are considered pathological, based on specific CT morphological criteria.
  • For immunotherapy trials, the review stated that recording RECIST 1.1 measurements alongside iRECIST measurements is encouraged, because immune-related pseudoprogression can make tumor response hard to assess.
• The authors' conclusion: The authors concluded that guidelines for evaluating pleural mesothelioma treatment response should combine the principles of mRECIST 1.1 and iRECIST, and that only a standardized study methodology can make the study of pleural mesothelioma reproducible and correct.

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, Modified RECIST (mRECIST), Mediastinum, CT Scan, Mesothelioma.

Related studies

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• A practical guide to measure "all" malignant pleural mesothelioma tumors by modified RECIST criteria? — K. Nackaerts, J. Vansteenkiste, et al. (2011)
• An overview on multimodal imaging for the diagnostic workup of pleural mesothelioma — M. Gabelloni, L. Faggioni, et al. (2024)
• CT imaging of peritoneal carcinomatosis and its mimics — A.D. Diop, M. Fontarensky, et al. (2014)
• Imaging of occupational lung disease — K.I. Kim, C.W. Kim, et al. (2001)
• Somatic and visceral solitary fibrous tumors in the abdomen and pelvis: cross-sectional imaging spectrum — A.K. Shanbhogue, S.R. Prasad, et al. (2011)

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