Role of Diffusion MRI in Differentiation between the Common Pediatric Posterior Fossa Brain Tumors

Abstract

B rain tumors are the most prevalent solid tumors in children. In children older than 1 year of age, most tumors are located within the posterior fossa. Pilocytic astrocytomas (PAs), medulloblastomas (MBs), and ependymomas are the most common pediatric posterior fossa tumors, high-grade gliomas, atypical teratoid/rhabdoid tumor (ATRT), and choroid plexus papilloma (CPP) of the fourth ventricle are less frequent. Although MR imaging is essential for diagnosis and evaluation of brain tumors, it offers limited information regarding tumor type and grade and is frequently far from being a definite diagnostic test, which is a role reserved for histology. Accurate preoperative diagnosis is an important goal in pediatric patients with posterior fossa neoplasm, because the different tumors dictate the need for different surgical approaches and have significantly different natural histories and outcomes. Advanced MRI techniques have shown to provide important additional information about the biological, physiological, and metabolic features of brain tumors. Recent studies suggested that diffusion weighted imaging (DWI) may effectively distinguish between various posterior fossa tumor types and histological grades.