Pediatric Posterior Fossa Medulloblastoma: The Role of Diffusion Imaging in Identifying Molecular Groups

J Neuroimaging. 2020 Jul;30(4):503-511. doi: 10.1111/jon.12704. Epub 2020 Jun 12.

Abstract

Background and purpose: The molecular groups WNT activated (WNT), Sonic hedgehog activated (SHH), group 3, and group 4 are biologically and clinically distinct forms of medulloblastoma. We evaluated apparent diffusion coefficient (ADC) values' utility in differentiating/predicting medulloblastoma groups at the initial diagnostic imaging evaluation and prior to surgery.

Methods: We retrospectively measured the ADC values of the enhancing, solid portion of the tumor (EST) and of the whole tumor (WT) and performed Kruskal-Wallis testing to compare the absolute tumor ADC values and cerebellar and thalamic ratios of three medulloblastoma groups (WNT, SHH, and group 3/group 4 combined).

Results: Ninety-three children (65 males) were included. Fifty-seven children had group 3/group 4, 27 had SHH, and 9 had WNT medulloblastomas. The median absolute ADC values in the EST and WT were .719 × 10-3 and .864 × 10-3 mm2 /s for group 3/group 4; .660 × 10-3 and .965 × 10-3 mm2 /s for SHH; and .594 × 10-3 and .728 × 10-3 mm2 /s for WNT medulloblastomas (P = .02 and .13). The median ratio of ADC values in the EST or the WT to normal cerebellar tissue was highest for group 3/group 4 and lowest for WNT medulloblastomas (P = .03 and .09), with similar results in pairwise comparisons of the corresponding thalamic ADC values (P = .02 and .06).

Conclusion: ADC analysis of a tumor's contrast-enhancing solid portion may aid preoperative molecular classification/prediction of pediatric medulloblastomas and may facilitate optimal surgical treatment planning, reducing surgery-induced morbidity.

Keywords: Apparent diffusion coefficient; diffusion-weighted imaging; medulloblastoma; molecular groups; posterior fossa tumors.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Child
  • Child, Preschool
  • Diffusion Magnetic Resonance Imaging / methods*
  • Female
  • Hedgehog Proteins / genetics
  • Humans
  • Infant
  • Infratentorial Neoplasms / diagnostic imaging*
  • Infratentorial Neoplasms / genetics
  • Infratentorial Neoplasms / pathology
  • Male
  • Medulloblastoma / diagnostic imaging*
  • Medulloblastoma / genetics
  • Medulloblastoma / pathology
  • Retrospective Studies
  • Wnt Proteins / genetics

Substances

  • Hedgehog Proteins
  • Wnt Proteins