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MR imaging of thymomas: a combined radiomics nomogram to predict histologic subtypes

Abstract

Objectives

Accurately predicting the WHO classification of thymomas is urgently needed to optimize individualized therapeutic strategies. We aimed to develop and validate a combined radiomics nomogram for personalized prediction of histologic subtypes in patients with thymomas.

Methods

A total of 182 thymoma patients were divided into training (n = 128) and test (n = 54) cohorts. Radiomics features were extracted from T2-weighted, T2-weighted fat suppression, and diffusion-weighted images to establish a radiomics signature in the training cohort. Multivariate logistic regression analysis was used to develop a combined radiomics nomogram that incorporated clinical, conventional MR imaging variables, apparent diffusion coefficient (ADC) value, and radiomics signature. The efficacy of clinical, conventional MR imaging, or ADC model was also evaluated respectively. The performances of different models were compared by receiver operating characteristic analysis and Delong test. The discrimination, calibration, and clinical usefulness of the combined radiomics nomogram were assessed.

Results

The radiomics signature, consisting of 14 features, achieved favorable predictive efficacy in differentiating low-risk from high-risk thymomas, outperforming clinical, conventional MR imaging, and ADC models. The combined radiomics nomogram incorporating tumor shape, ADC value, and radiomics signature yielded the best performance (training cohort: area under the curve [AUC] = 0.946, test cohort: AUC = 0.878). The calibration curve and decision curve analysis indicated the clinical utility of the combined radiomics nomogram.

Conclusions

The radiomics signature is a useful tool that can be used to predict histologic subtypes of thymomas. The combined radiomics nomogram improved the individualized subtype prediction in patients with thymomas.

Key Points

Fourteen robust features were selected to develop a radiomics signature for preoperative prediction of thymoma subtype.

MRI-based radiomics signature can differentiate low-risk thymomas from high-risk thymomas with favorable predictive efficacy compared with clinical, conventional MR imaging, and ADC models.

Combined radiomics nomogram based on tumor shape, ADC value, and radiomics signature could improve the individualized subtype prediction in patients with thymomas.

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Abbreviations

ADC:

Apparent diffusion coefficient

DCA:

Decision curve analysis

FS:

Fat suppression

ICC:

Inter- and intra-class correlation coefficient

LASSO:

Least absolute shrinkage and selection operator

OR:

Odds ratio

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Acknowledgments

We would like to thank Dr. Xiao-Cheng Wei and Dr. Min Li in GE Healthcare China for providing technical support regarding the MR imaging examination of the thorax.

Funding

This study has received funding by the Science and Technology Innovation Development Foundation of Tangdu Hospital (no. 2017LCYJ004).

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Authors

Corresponding authors

Correspondence to Wen Wang or Guang-Bin Cui.

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Guarantor

The scientific guarantor of this publication is Guang-Bin Cui.

Conflict of interest

One of the authors of this manuscript (Jia-Liang Ren) is an employee of GE Healthcare. The remaining authors declare no relationships with any companies whose products or services may be related to the subject matter of the article.

Statistics and biometry

Gang Xiao and Jia-Liang Ren kindly provided statistical advice for this manuscript.

Informed consent

Written informed consent was waived by the Institutional Review Board.

Ethical approval

Institutional Review Board approval was obtained.

Study subjects or cohorts overlap

Some study subjects or cohorts have been previously reported in European Radiology: Li B, Xin YK, Xiao G et al (2019) Predicting pathological subtypes and stages of thymic epithelial tumors using DWI value of combining ADC and texture parameters. European Radiology 29:5330–5340.

Methodology

• retrospective

• diagnostic or prognostic study

• performed at one institution

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Xiao, G., Hu, YC., Ren, JL. et al. MR imaging of thymomas: a combined radiomics nomogram to predict histologic subtypes. Eur Radiol 31, 447–457 (2021). https://doi.org/10.1007/s00330-020-07074-3

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  • DOI: https://doi.org/10.1007/s00330-020-07074-3

Keywords

  • Thymoma
  • Magnetic resonance imaging
  • Nomograms
  • Machine learning