Delayed-Phase Enhancement for Evaluation of Malignant Pleural Mesothelioma on Computed Tomography: A Prospective Cohort Study

Our plain-English summary of Delayed-Phase Enhancement for Evaluation of Malignant Pleural Mesothelioma on Computed Tomography: A Prospective Cohort Study, by A. Patel, L. Roshkovan, S. McNulty, et al (Clinical Lung Cancer, 2021).

The study

• Authors: A. Patel, L. Roshkovan, S. McNulty, E. Alley, D.A. Torigian, A.C. Nachiappan, M. Galperin-Aizenberg, E.M. Barbosa, J. DiRienzi, I. Berger, U. Khalid, A.R. Haas, S. Singhal, E.P. Wileyto, K.A. Cengel, S.I. Katz
• Journal: Clinical Lung Cancer
• Published: 2021;22(3):210-217.e1
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Radiologic assessment of malignant pleural mesothelioma (MPM) on computed tomography (CT) imaging can be limited by similar attenuations of MPM and adjacent tissues. This can result in inaccuracies in defining the presence and extent of pleural tumor burden. We hypothesized that increasing the time delay for pleural enhancement will optimize discrimination between MPM and noncancerous tissues on CT. Here we conduct a prospective observational study to determine the optimal time delay for imaging MPM on CT.

Patients And Methods: Adult MPM patients (n = 15) were enrolled in this prospective exploratory imaging trial. Patients with < 1 cm MPM thickness, prior pleurectomy, pleurodesis, pleural radiotherapy, or antiangiogenic therapy were excluded. All patients underwent a dynamically-enhanced CT with multiple time delays (0 - 10 minutes) after intravenous contrast administration. Tumor tissue attenuation was measured at each phase of enhancement. A qualitative assessment of tumor enhancement kinetics was also performed. The optimal phase of enhancement based on qualitative lesion conspicuity and quantitative tumor enhancement was then compared.

Results: MPM tumor enhancement was quantitatively and qualitatively increased at time delays beyond the conventional time delay for thoracic CT imaging (40-60 seconds). Patient tumor enhancement kinetics, displayed as the fraction of maximal tumor tissue attenuation as a function of time, revealed an optimal time delay of 230 to 300 seconds after intravenous contrast administration. There was an association between degree of tumor enhancement and subjective lesion conspicuity.

Conclusion: Optimal MPM contrast enhancement occurs at a later phase than typically acquired with conventional thoracic CT imaging.

Copyright © 2020 The Author(s). Published by Elsevier Inc. All rights reserved.

In plain English

This was a small prospective exploratory imaging study. It did not examine asbestos exposure. It asked how long after an injection of contrast dye a CT scan should be taken to best show malignant pleural mesothelioma. Fifteen consecutive adults with biopsy-proven pleural mesothelioma thicker than 1 cm, treated at the authors' institution in 2016-2018, were enrolled. None had prior pleurectomy, systemic therapy, pleural radiotherapy or pleurodesis. Each was scanned repeatedly over a 5 cm section of the chest, from 20 seconds to 10 minutes after injection. In all 15 patients, tumor enhancement peaked later than the 40 to 60 seconds used in conventional scans, with an estimated optimal delay of 230 to 300 seconds. The difference between tumor and chest wall muscle was estimated to be greatest at 240 to 260 seconds. Reviewing radiologists most often judged the tumor most visible at 240 seconds (7 of 15 patients), then at 120 seconds (4 of 15). The authors concluded that optimal enhancement occurred at a substantially later time than in conventional chest CT in this small cohort. They 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: Prospective exploratory imaging study (described as a prospective cohort study) of dynamic contrast-enhanced CT
• Who was studied: 15 consecutive adults with biopsy-proven malignant pleural mesothelioma with measurable tumor over 1 cm, treated at the authors' institution (University of Pennsylvania) 2016-2018. 12 were men and 3 were women, mean age 70.3 years (range 61-80). Tumor types were 13 epithelial, 1 biphasic and 1 sarcomatoid. Patients with prior pleurectomy, systemic therapy, pleural radiotherapy or pleurodesis were excluded.
• Exposure: No asbestos exposure was studied. The study looked at timing of CT scans after intravenous contrast (Isovue 370): images at 20, 40 and 60 seconds and at 2, 4, 6, 8 and 10 minutes after injection.
• Main results:
  • In all 15 patients, tumor enhancement peaked at a later time than the conventional 40-60 second delay.
  • The estimated optimal time delay for tumor enhancement was 230 to 300 seconds after contrast injection.
  • The difference in enhancement between tumor and normal chest wall muscle was estimated to be greatest at 240 to 260 seconds.
  • Reviewing radiologists favored 240 seconds as the delay at which the tumor was most visible (7 of 15 patients, 47%), followed by 120 seconds (4 of 15, 27%).
  • For 2 patients there was no clearly favored delay, and for 2 others the 60-second delay was favored. One of the 60-second cases showed faster washout of enhancement than the other patients.
• The authors' conclusion: The authors concluded that, in this small cohort, optimal mesothelioma enhancement on CT occurred at a substantially greater time delay than in conventional chest CT. They proposed further study of adding a 2- to 4-minute delayed phase in a larger cohort.
• Limitations the authors state:
  • Small sample size; the authors note the study was exploratory and needs validation in a larger cohort.
  • Tumors were restricted to over 1 cm in thickness, and most were of the epithelial subtype.
  • No patients had prior treatment, so it is unknown whether the findings apply after treatment.
  • Only a 5 cm section of the chest was imaged, to limit radiation dose, rather than the whole chest.

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, Cohort Study, Tumor Burden, Pleurodesis.

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• Low-dose computed tomography screening for lung cancer and pleural mesothelioma in an asbestos-exposed population: baseline results of a prospective, nonrandomized feasibility trial--an Alpe-adria Thoracic Oncology Multidisciplinary Group Study (ATOM 002) — G. Fasola, O. Belvedere, et al. (2007)

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