MR Imaging of Pediatric Posterior Fossa Tumors

Abstract

A wide spectrum of tumors or tumor-like masses can involve the intracranial posterior fossa in the pediatric population. The multiplanar capabilities of MR imaging and its sophisticated new pulse sequences allow improved detection and characterization of posterior fossa tumors. Determining whether a mass is intra- or extra-axial remains paramount in limiting the differential diagnosis. This article reviews the imaging characteristics of the most common pediatric posterior fossa tumors (i.e., gliomas, medulloblastoma, and ependymoma). In addition, the use and benefits of H-NMR spectral analysis, diffusion-weighted imaging (DWI), and apparent diffusion coefficient maps will be addressed. Symptoms of posterior fossa masses in children usually include early morning headaches, vomiting, cranial nerve palsies, and dysmetria (i.e., abnormalities of movement caused by cerebellar dysfunction).