ROLE OF DIFFUSION WEIGHTED MRI IN DIFFERENTIAL DIAGNOSIS OF PAEDIATRIC POSTERIOR FOSSA TUMORS

Abstract

Background: Infratentorial tumors accounts for 65% of all paediatric tumors, and most common infratentorial tumors in children include juvenile pilocytic astrocytoma (JPA), medulloblastoma, ependymoma and brainstem glioma. An accurate diagnosis has important clinical implications related to treatment and prognosis. DWI and ADC maps provide information regarding the cellularity of tumors and have an important role in the preoperative differentiation of different tumor types.
 Aim: To evaluate the role of DWI and ADC measurement in distinguishing between the most common pediatric posterior fossa tumors.
 Methods: In this study, we evaluated 25 paediatric patients aged between 1 to 15 years suspected to have posterior fossa mass on the CT referred from neurosurgery department to our department for MRI brain. All these patients subjected to conventional MRI followed by diffusion MR imaging and calculation of the ADC values. Written consent was taken from the guardians.
 Results: In juvenile pilocytic astrocytoma ( n = 10), ADC values ranged between 1.3 and 1.9 × 10?3 mm2/s, ependymoma (n = 8), ADC values ranged between 1.1 and 1.5 × 10?3 mm2/s and medulloblastoma (n = 7), ADC values ranged between 0.45 and 0.9 × 10?3 mm2/s. Statistically significant difference in ADC value was detected between JPA, ependymomas and medulloblastomas, while no statistically significant difference was detected between JPA and ependymomas.
 Conclusion: Diffusion Imaging plays an important role in demonstrating the features of posterior fossa brain tumours for appropriate diagnosis of medulloblastomas, ependymomas, and pilocytic astrocytoma.
 Keywords: DWI, MRI, Posterior fossa