Dynamic contrast-enhanced MRI of malignant pleural mesothelioma: a comparative study of pharmacokinetic models and correlation with mRECIST criteria

Our plain-English summary of Dynamic contrast-enhanced MRI of malignant pleural mesothelioma: a comparative study of pharmacokinetic models and correlation with mRECIST criteria, by M. Vivoda Tomšič, S. Bisdas, V. Kovač, et al (Cancer Imaging, 2019).

The study

• Authors: M. Vivoda Tomšič, S. Bisdas, V. Kovač, I. Serša, K. Šurlan Popovič
• Journal: Cancer Imaging
• Published: 2019;19(1):10
• Cited by: 11 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Malignant pleural mesothelioma (MPM) is a rare and aggressive thoracic malignancy that is difficult to cure. Dynamic contrast-enhanced (DCE) MRI is a functional imaging technique used to analyze tumor microvascular properties and to monitor therapy response. Purpose of this study was to compare two tracer kinetic models, the extended Tofts (ET) and the adiabatic approximation tissue homogeneity model (AATH) for analysis of DCE-MRI and examine the value of the DCE parameters to predict response to chemotherapy in patients with MPM.

Method: This prospective, longitudinal, single tertiary radiology center study was conducted between October 2013 and July 2015. Patient underwent DCE-MRI studies at three time points: prior to therapy, during and after cisplatin-based chemotherapy. The images were analyzed using ET and AATH models. In short-term follow-up, the patients were classified as having disease control or progressive disease according to modified response evaluation criteria in solid tumors (mRECIST) criteria. Receiver operating characteristic curve analysis was used to examine specificity and sensitivity of DCE parameters for predicting response to therapy. Comparison tests were used to analyze whether derived parameters are interchangeable between the two models.

Results: Nineteen patients form the study population. The results indicate that the derived parameters are not interchangeable between the models. Significant correlation with response to therapy was found for AATH-calculated median pre-treatment efflux rate (kep) showing sensitivity of 83% and specificity of 100% (AUC 0.9). ET-calculated maximal pre-treatment kep showed 100% sensitivity and specificity for predicting treatment response during the early phase of the therapy and reached a favorable trend to significant prognostic value post-therapy.

Conclusion: Both models show potential in predicting response to therapy in MPM. High pre-treatment kep values suggest MPM disease control post-chemotherapy.

In plain English

This prospective study, at a single radiology center between October 2013 and July 2015, examined dynamic contrast-enhanced MRI, a scan used to study tumor blood vessels, in people with malignant pleural mesothelioma receiving cisplatin-based chemotherapy. Asbestos exposure was not studied. Of 29 patients recruited, 19 (16 men, 3 women) were scanned before, during and after chemotherapy. The two computer models used to analyze the scans (ET and AATH) produced differing values. By tumor-size criteria (mRECIST), 13 patients had disease control and 6 had progressive disease. Before treatment, the maximal value of a scan measure called kep from the ET model was 41% higher in the disease-control group, with response assessed during and after treatment. The median kep value from the AATH model was 61% higher, with response assessed after treatment. Median pre-treatment AATH kep predicted response after chemotherapy with 83.3% sensitivity and 100% specificity. Maximal pre-treatment ET kep predicted response during treatment with 100% sensitivity and specificity, but its after-chemotherapy result (P = 0.06) was not statistically significant. The authors concluded that high pre-treatment kep values suggest disease control after chemotherapy. They named the small number of patients as the main limitation.

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, longitudinal, single-center imaging study comparing two tracer kinetic models (extended Tofts, ET, and adiabatic approximation tissue homogeneity, AATH) for analyzing dynamic contrast-enhanced MRI (DCE-MRI), and testing whether DCE parameters predict response to chemotherapy
• Who was studied: Patients with biopsy-proven malignant pleural mesothelioma eligible for chemotherapy. 29 consecutive patients were recruited and 19 formed the study population (16 men, 3 women; median age 68, range 46 to 84), at a single tertiary radiology center, October 2013 to July 2015
• Exposure: Not an asbestos exposure study. Patients received cisplatin-based chemotherapy (with gemcitabine or pemetrexed) and had DCE-MRI before, during (after the third cycle) and after chemotherapy
• Main results:
  • By mRECIST, 6 of the 19 patients had progressive disease and 13 had disease control (stable disease or partial response)
  • DCE parameter values differed between the ET and AATH models. The vp values differed in all measurements
  • Bland-Altman analysis of kep between the two models showed a small negative mean difference of minus 0.08 (95% CI minus 0.14 to minus 0.02). The authors said kep values are generally interchangeable, but the ET model seems to overestimate kep relative to AATH in tumors with high kep
  • Within each model, there was no statistically significant difference in DCE values over the course of chemotherapy
  • In the disease-control group, maximal pre-treatment ET-calculated kep values were higher by 41%. The difference between the progressive disease and disease control groups was significant with response assessed after the third cycle (P = 0.01) and post-treatment (P = 0.04)
  • In the disease-control group, median pre-treatment AATH-calculated kep values were higher by 61%. The difference between groups was assessed post-treatment (P = 0.019)
  • Maximal pre-treatment ET-calculated kep predicted response during treatment with estimated sensitivity and specificity of 100% (P less than 0.001; cut-off 0.89 per minute or higher; AUC 1)
  • For response after chemotherapy, maximal pre-treatment ET-calculated kep was less predictive: sensitivity 83.3% and specificity 92.3% (P = 0.06; cut-off 1.31 per minute or higher; AUC 0.81)
  • Median pre-treatment AATH-calculated kep predicted response after treatment with sensitivity 83.3% and specificity 100% (P less than 0.0001; cut-off 0.13 per minute or higher; AUC 0.92)
  • Other DCE parameters showed no predictive value for response to therapy
• The authors' conclusion: The authors concluded that both models show potential in predicting response to therapy in malignant pleural mesothelioma, and that high pre-treatment kep values suggest disease control after chemotherapy
• Limitations the authors state:
  • Relatively small number of patients, which the authors called the first and main limitation
  • Extended anatomical coverage was needed, which limited spatial and temporal resolution
  • Not all tumor foci were included in the scans, so tumor heterogeneity was not fully accounted for
  • Endpoints did not include progression or overall survival time

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, Chemotherapy, Cisplatin, Modified RECIST (mRECIST).

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