Findings on preoperative brain MRI predict histopathology in children with cerebellar neoplasms.

BACKGROUND/AIMS The majority of pediatric patients with cerebellar neoplasms harbor pilocytic astrocytomas (PAs), medulloblastomas, or ependymomas. Knowledge of a preoperative likelihood of histopathology in this group of patients has the potential to influence many aspects of care. Previous studies have demonstrated hyperintensity on diffusion-weighted imaging to correlate with medulloblastomas. Recently, measurement of T(2)-weighted signal intensity (T2SI) was shown to be useful in identification of low-grade cerebellar neoplasms. The goal of this study was to assess whether objective findings on these MRI sequences reliably correlated with the underlying histopathology. METHODS We reviewed the radiologic findings of 50 pediatric patients who underwent resection of a cerebellar neoplasm since 2003 at our institution. Region of interest placement was used to calculate the relative diffusion-weighted signal intensity (rDWSI) and relative T2SI (rT2SI) of each neoplasm. RESULTS Tukey's multiple comparison test demonstrated medulloblastomas to have significantly higher rDWSIs than PAs/ependymomas, and PAs to have significantly higher rT2SIs than medulloblastomas/ependymomas. A simple method consisting of sequential measurement of rDWSI and rT2SI to predict histopathology was then constructed. Using this method, 39 of 50 (78%) tumors were accurately predicted. CONCLUSION Measurement of rDWSI and rT2SI using standard MRI of the brain can be used to predict histopathology with favorable accuracy in pediatric patients with cerebellar tumors.