A comparison between MRI and CT in the assessment of primary tumour volume in mesothelioma

Our plain-English summary of A comparison between MRI and CT in the assessment of primary tumour volume in mesothelioma, by S. Tsim, G.W. Cowell, A. Kidd, et al (Lung Cancer, 2020).

The study

• Authors: S. Tsim, G.W. Cowell, A. Kidd, R. Woodward, L. Alexander, C. Kelly, J.E. Foster, K.G. Blyth
• Journal: Lung Cancer
• Published: 2020;150:12-20
• Cited by: 18 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Introduction: Primary tumour staging in Malignant Pleural Mesothelioma (MPM) using Computed Tomography (CT) imaging is confounded by perception errors reflecting low spatial resolution between tumour and adjacent structures. Augmentation using perfusion CT is constrained by radiation dosage. In this study, we evaluated an alternative tumour staging method using perfusion-tuned Magnetic Resonance Imaging (MRI).

Methods: Consecutive patients with suspected MPM were recruited to a prospective observational study. All had MRI (T1-weighted, isotropic, contrast-enhanced 3-Tesla perfusion imaging) and CT (contrast-enhanced) pre-biopsy. Patients diagnosed with MPM underwent MRI and CT volumetry, with readers blinded to clinical data. MRI volumetry was semi-automated, using signal intensity limits from perfusion studies to grow tumour regions within a pleural volume. A similar CT method was not possible, therefore all visible tumour was manually segmented. MRI and CT volumes were compared (agreement, correlation, analysis time, reproducibility) and associations with survival examined using Cox regression.

Results: 58 patients were recruited and had MRI before biopsy. 31/58 were diagnosed with MPM and these scans were used for volumetry. Mean (SD) MRI and CT volumes were 370 cm3 and 302 cm3, respectively. MRI volumes were larger (average bias 61.9 cm3 (SD 116), 95 % limits (-165.5 - 289 cm3), moderately correlated with CT (r = 0.56, p = 0.002) and independently associated with survival (HR 4.03 (95 % CI 1.5-11.55), p = 0.006). CT volumes were not associated with survival, took longer to compute than MRI volumes (mean (SD) 151 (19) v 14 (2) minutes, p=<0.0001) and were less reproducible (inter-observer ICC 0.72 for CT, 0.96 for MRI).

Conclusions: MRI and CT generate different tumour volumes in MPM. In this study, MRI volumes were larger and were independently associated with survival. MRI volumetry was quicker and more reproducible than CT.

Copyright © 2020 Elsevier B.V. All rights reserved.

In plain English

This prospective observational study, recruiting patients from January 2013 to October 2016, compared MRI and CT for measuring the main tumour's volume in malignant pleural mesothelioma. Of 58 patients with suspected mesothelioma who had both scans before biopsy, 31 were diagnosed with the disease. Of these, 27 were asbestos-exposed; fiber types were not reported. Tumour volume was measured semi-automatically on MRI in all 31 and by hand on CT in 28. Mean volume was 370 cm3 by MRI and 302 cm3 by CT; the measures were moderately correlated. Survival was significantly lower in patients whose MRI volume was 300 cm3 or more. In a combined analysis, MRI volume (hazard ratio 4.03, 95% CI 1.5 to 11.55) and haemoglobin were the only independent predictors of survival. CT volume was not significantly associated with survival. CT measurement took a mean of 151 minutes, MRI 14. Agreement between readers was lower for CT (ICC 0.72) than for MRI (0.962). The authors concluded that the MRI method appears accurate, reproducible and reasonably practical. Because the sample was small, they said it must be externally validated.

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 observational imaging study (pilot study plus an MRI sub-study within the DIAPHRAGM study) comparing MRI and CT tumour volume measurement
• Who was studied: 58 patients with suspected malignant pleural mesothelioma who had MRI and CT before pleural intervention; 31 of them diagnosed with mesothelioma and included in volume analyses (31 MRI, 28 CT); 28 of 31 male, mean age 76
• Exposure: The study compared imaging methods (contrast-enhanced 3-Tesla perfusion MRI versus contrast-enhanced CT), not asbestos exposure. 27 of the 31 mesothelioma patients were asbestos-exposed; fiber types, products and jobs were not reported.
• Main results:
  • In patients with mesothelioma, mean tumour volume was 370 (SD 137) cm3 by MRI (n = 31) and 302 (SD 102) cm3 by CT (n = 28), a mean difference of 69 cm3 (p = 0.009)
  • MRI and CT volumes were moderately correlated (Pearson's r 0.56, p = 0.002)
  • Among all 31 mesothelioma patients (median overall survival 14 months), survival was significantly lower in those with higher MRI tumour volume, with volume split around 300 cm3; in univariate analysis MRI volume of 300 cm3 or more versus less than 300 cm3 had HR 2.273 (95% CI 1.162 to 4.446, p = 0.016)
  • In the multivariable Cox model, haemoglobin and MRI tumour volume were the only independent prognostic factors (MRI volume HR 4.03, 95% CI 1.5 to 11.55, p = 0.006)
  • CT tumour volume was not significantly associated with survival when split around 300 cm3, and was not independently associated with survival, although it approached statistical significance in univariate analyses
  • CT volume analysis took a mean of 151 (SD 19) minutes, compared with 14 (SD 2) minutes for MRI (p less than 0.0001)
  • For MRI, intra-observer ICC was 0.875 and inter-observer ICC was 0.962 (95% CI 0.893 to 0.987); for CT, inter-observer ICC was 0.72
  • The median difference in volume between the two CT readers (75.5 cm3) was not significantly different from that between the MRI readers (47 cm3) (p = 0.15)
  • Neither MRI volume nor CT volume correlated with clinical T-stage
• The authors' conclusion: The authors concluded that their perfusion-tuned MRI volume method appears accurate, reproducible and reasonably practical in patients with malignant pleural mesothelioma, and that it was quicker and more reproducible than CT.
• Limitations the authors state:
  • Small sample size, so the method needs external validation
  • CT and MRI scans were not done on the same day (median 19 days apart)
  • CT scans came from routine clinical care and did not follow a study protocol
  • The quick MRI analysis time assumes the signal intensity limits used can be applied to all mesothelioma patients; otherwise extra analysis per patient would be needed

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: Mesothelioma, Staging, Pleural Mesothelioma, Biopsy.

Related studies

• Diagnostic and Prognostic Biomarkers in the Rational Assessment of Mesothelioma (DIAPHRAGM) study: protocol of a prospective, multicentre, observational study — S. Tsim, C. Kelly, et al. (2016)
• 18F-FDG PET Assessment of Malignant Pleural Mesothelioma: Total Lesion Volume and Total Lesion Glycolysis-The Central Role of Volume — J.C. Reynolds, R. Maass-Moreno, et al. (2020)
• Early Contrast Enhancement: A novel magnetic resonance imaging biomarker of pleural malignancy — S. Tsim, C.A. Humphreys, et al. (2018)
• Optimal gross tumor volume definition in lung-sparing intensity modulated radiotherapy for pleural mesothelioma: an in silico study — A. Botticella, G. Defraene, et al. (2016)
• Comparison of expert and job-exposure matrix-based retrospective exposure assessment of occupational carcinogens in The Netherlands Cohort Study — N.S. Offermans, R. Vermeulen, et al. (2012)
• A comparison of the results from intra-pleural and intra-peritoneal studies with those from inhalation and intratracheal tests for the assessment of pulmonary responses to inhalable dusts and fibres — G. Drummond, R. Bevan, et al. (2016)

Browse more research in Lung Cancer, or return to medical research.