Changes mimicking new leptomeningeal disease after intensity-modulated radiotherapy for medulloblastoma

Int J Radiat Oncol Biol Phys. 2009 Jan 1;73(1):214-21. doi: 10.1016/j.ijrobp.2008.03.056. Epub 2008 May 15.


Purpose: Acute and late changes in magnetic resonance imaging of the pediatric brain have been described after radiotherapy (RT). We report the post-RT neuroimaging changes in the posterior fossa after intensity-modulated RT (IMRT) in children with medulloblastoma and contrast them with those of leptomeningeal disease.

Methods and materials: We performed a retrospective review of 53 consecutive children with medulloblastoma who were treated with craniospinal RT followed by IMRT to the posterior fossa and chemotherapy between 1997 and 2006.

Results: After IMRT to the posterior fossa, 8 (15%) of 53 patients developed increased fluid-attenuated inversion-recovery signal changes in the brainstem or cerebellum and patchy, multifocal, nodular contrast enhancement at a median of 6 months. The enhancement superficially resembled leptomeningeal disease. However, the enhancement resolved without intervention at a median of 6 months later. The accompanying fluid-attenuated inversion-recovery signal changes occasionally preceded the enhancement, were often parenchymal in location, and resolved or persisted to a lesser degree. All 8 patients with transient magnetic resonance imaging changes in the posterior fossa were alive at last follow-up. In contrast, leptomeningeal disease occurred in 8 (15%) of our 53 patients at a median of 19.5 months after IMRT completion. Of these 8 patients, 7 demonstrated initial nodular enhancement outside the conformal field, and 7 patients died.

Conclusion: Magnetic resonance imaging changes can occur in the posterior fossa of children treated with IMRT for medulloblastoma. In our experience, these transient changes occur at a characteristic time and location after RT, allowing them to be distinguished from leptomeningeal disease.

Publication types

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

MeSH terms

  • Adolescent
  • Brain Neoplasms / radiotherapy*
  • Child
  • Child, Preschool
  • Diagnosis, Differential
  • Female
  • Humans
  • Male
  • Medulloblastoma / radiotherapy*
  • Meningeal Neoplasms / diagnosis*
  • Meningeal Neoplasms / etiology*
  • Meningioma / diagnosis*
  • Meningioma / etiology*
  • Radiation Injuries / diagnosis*
  • Radiation Injuries / etiology*
  • Radiotherapy, Conformal / adverse effects*