Mariam Aboian

Tremendous advances have been made in the genetic characterization and classification of adult brain tumors, but the classification of pediatric brain tumors with respect to their genetic characteristics has not been as well characterized. In the 2016 WHO Classification of Tumors of the Central Nervous System, a new class of brain tumors was described: diffuse midline glioma with histone H3 K27M mutation. This tumor occurs predominantly in children, and the presence of the histone H3 K27M mutation has been associated with worse patient outcomes.¹ In our manuscript, we characterized the MR imaging patterns of diffuse midline gliomas that had the histone H3 mutation and compared them with diffuse midline gliomas with wild-type histone H3.² We were surprised to discover that there were no qualitative differences in the imaging appearances of diffuse midline gliomas that had the histone H3 K27M mutation compared with the wild-type tumors. In our manuscript, we provided a detailed imaging characterization of this new class of tumors in a large cohort of children, which will serve as an important reference for neuroradiologists and general radiologists in practice.

Our work was enthusiastically welcomed by the imaging community at national and international meetings, including the ASNR 2016 meeting,³ because it was the first work to characterize the imaging features for this new class of tumors in a large cohort of patients.

We were able to characterize a large group of children with these tumors because of a strong pediatric neuro-oncology group at our institution that has a large referral base. We are fortunate to work with such dedicated colleagues, and we expanded our work into multiple additional projects focused on qualitative and quantitative imaging of diffuse midline gliomas with respect to their molecular characteristics. To perform a quantitative analysis, we established an image processing pipeline for processing radiomic features of tumors with ADC histogram analysis and tumor texture analysis. Our follow-up manuscript on the quantitative analysis of diffusion characteristics with respect to patient outcomes is currently under review for publication. We are also working closely on correlating gene expression patterns with mutations found within diffuse midline gliomas and their locations in the brain. We will present this work at the ASNR 2018 and ISMRM 2018 meetings. We plan on continuing our laboratory work on the radiogenomics of pediatric brain tumors and are also working on expanding our work into the molecular imaging of pediatric brain tumors. Our ultimate goal is to include imaging features of pediatric brain tumors in the WHO Classification of Tumors.

References

1. Castel D, Philippe C, Calmon R, et al. Histone H3F3A and HIST1H3B K27M mutations define two subgroups of diffuse intrinsic pontine gliomas with different prognosis and phenotypes.  Acta Neuropathol 2015;130:815–27.
2. Aboian MS, Solomon DA, Felton E, et al. Imaging characteristics of pediatric diffuse midline gliomas with histone H3 K27M mutation. AJNR Am J Neuroradiol 2017;38:795–800, 10.3174/ajnr.A5076.
3. Aboian MS, Solomon DA, Felton E, et al. Imaging characteristics of pediatric diffuse midline gliomas based on the presence of a poor prognostic marker histone H3 K27M mutation, in Proceedings of the American Society of Neuroradiology 54th Annual Meeting & the Foundation of the ASNR Symposium, Washington, DC. May 21–26, 2016

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