MRI Online: Imaging and 2021 WHO CNS Tumor Classification

Jul 16, 2024

Review flashcards

Noon Conference - MRI Online: Imaging and 2021 WHO CNS Tumor Classification (Dr. Sunmi Cha)

About Noon Conference

  • Connects global Radiology community through free live webinars.
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  • Recordings available by creating a free MRI online account.
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Speaker Introduction

  • Dr. Sunmi Cha
    • Neuroradiology fellowship at NYU Medical Center.
    • Expertise in brain tumor Imaging at UCSF Medical Center.
    • Program Director of Diagnostic Radiology Residency and Vice Chair of Education at UCSF.

Lecture Objectives

  • Highlight key points from the 2021 WHO CNS tumor classification.
  • Discuss the relevance to neuroradiologists and general radiologists.
  • Correlation of molecular genetic markers with Imaging.
  • Case illustrations showing the relationship between Imaging, neuropathology, and neuromolecular genetics.

WHO CNS Tumor Classification

  • History: Started in 1979, updated through 2000, 2007, 2016, and 2021.
  • 2016 Update: Molecular genetic information included in classification.
  • 2021 Update: Fifth edition, increased importance of Imaging.
    • Notable point: MRI images on the cover of the classification book.
  • Key Points:
    • Molecular genetic markers are now central to tumor classification.
    • Introduction of markers like IDH status and UCSF 500 Gene panel.

Imaging Techniques

  • Structural MRI: Essential for assessing tumor appearance.
  • Physiologic MRI: Analyze vascularity, metabolism, etc.
    • Examples: PET CT/PET MR to distinguish recurrent tumors from radiation necrosis.
  • Key Sequences in Structural MRI: Pre-post T1, T2, FLAIR, DWI, ADC, SWI, ASL perfusion Imaging.
    • SWI (Susceptibility Weighted Imaging): Important for assessing blood products.
    • DWI (Diffusion Weighted Imaging): Essential for differentiating abscesses, cellular tumors, infarcts.
    • Perfusion Imaging: Helpful for identifying hypervascular tumors.
  • Spectroscopy: Used as a problem-solving tool; identifies different metabolic profiles.

Pediatric Tumors

Medulloblastoma

  • Divided into four subtypes: WNT, Sonic Hedgehog, Group 3, Group 4.
    • WNT subtype: Off midline.
    • Sonic Hedgehog subtype: Hemispheric with multi-nodular solid components.
    • Group 3: Midline, highly enhancing.
    • Group 4: Midline, less enhancing.

Ependymoma

  • Superficially appearing in posterior fossa or spinal cord.
  • Two subtypes: PFA (Asymmetric) and PFB (Midline/ball-shaped).
    • PFA: Off midline, more aggressive.
    • PFB: Midline, less aggressive, better prognosis.

Diffuse Midline Glioma

  • Affects midline structures (thalamus, brainstem)
  • Defined by H3 K27M mutation

Adult Tumors

Solitary Fibrous Tumor and Hemangio Pericytoma

  • Related by STAT6 nuclear expression.

Pilocytic Astrocytoma, Ganglioglioma, and PXAs

  • Often share BRAF V600E mutation.

Molecular Glioblastoma

  • IDH wild-type with mutations in TERT promoter, EGFR, Trisomy 7 and Monosomy 10.

Diffuse Gliomas

  • IDH mutant or wild type.
    • Diffuse Astromcytoma: Optionally ATRX loss or 1p/19q co-deletion (Oligodendrogliomas).

Conclusion & Summary

  • 2021 WHO CNS classification: Significant changes with the inclusion of molecular genetic markers.
  • Structural and physiologic MR: Importance reiterated.
  • Molecular genetic profiles: Essential for proper imaging and diagnosis correlation.
  • Continuous evolution in classification expected.

Q&A Section

Key topics discussed:

  • ATRT tumor classification
  • Gliomatosis cerebri
  • Relevance of relay fusion in ependymomas