E1657. Imaging Correlates of Genotyping and Molecular Markers for Low and High-Grade Glioma
  1. Aline Camargo; Hershey Medical Center
  2. Sangam Kanekar; Hershey Medical Center
2016 CNS WHO classifications integrated the phenotypic and genotypic parameters of the brain tumors. Since then pheno- and genotyping using the tumor tissue has become the gold standard for characterizing the histologic and genetic make of the tumor which decide the surgical approach, the choice of the chemo and/or radiotherapy and in turn Overall survival (OS) and have a progression-free survival (PFS) for the patient. However, pathology and genotypic have their own limitations: of invasiveness, the cost involved, and more important limited availability across the globe. Noninvasive technique such as MRI (structural and molecular) imaging plays an important role in the radio-histogenomic classification of the brain tumor. Molecular imaging using various MRI techniques, DWI-ADC, MR spectroscopy, MR perfusion, and DTI has shown some promising results in understanding the genetic profile and the biological behavior of the tumor.

Educational Goals / Teaching Points
To discuss the gliomagenesis and associated molecular markers with various gliomas To correlate the imaging findings with the various Genotyping and molecular markers in low grade and diffuse glioma.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
We retrospectively reviewed the imaging studies from our PACS system of 55 patients with glioma (low, diffuse gliomas and glioblastoma), which forms the basis of this exhibit. All patients had undergone basic MRI plus advanced imaging techniques such as MR spectroscopy, MR perfusion (dynamic susceptibility contrast magnetic resonance (MR) perfusion, DTI, fMRI, and ADC value calculation. 46 of these tumors had a histopathology correlation with the imaging findings. Imaging parameters: site, size, margins, enhancing pattern, nonenhancing component, T2-FLAIR mismatch, necrosis area, percentage of necrosis area inside the enhancing lesion, ADC values, rCBV, multivoxel chemical shift MR spectroscopy, and FA and MD value calculations from DTI. Various imaging markers were correlated with the phenol and genotyping markers. For easy understanding of this exhibit, we have categorized this exhibit under following heading: isocitrate dehydrogenase (IDH) status, O6-Methylguanine-DNA methyltransferase (MGMT), molecular genetics of glioblastoma and gliomagenesis, Alpha-thalassemia/mental retardation syndrome X-linked (ATRX) and TP53 mutations, 1p/19q codeletion as a marker for oligodendroglial tumors, Diffuse midline glioma and H3 K27M-mutant and TERT promoter mutations.

1. In conclusion, the treatment of the brain tumors gets more personalized and moves toward targeted therapeutics due to a better understanding of the tumor genetics and molecular markers. However, as the number and importance of distinct genetic mutations increase, there is a significant increase in the cost. 2. Various gene mutations reflect alterations in metabolism, cellularity, and angiogenesis, which manifest characteristic features on FLAIR-T2, DWI-ADC, MR spectroscopy, and DSC-PWI. Imaging, though, at present cannot replace the genetic panel but has shown some promising direct and ancillary signs in identifying and diagnosing the types and subtypes of glioma.