Abstract
Integrated diagnosis based on the WHO 2016 update is important for the treatment of pediatric brain tumors. This integrated diagnosis is based on the pathological specimen obtained by surgery. Accurate preoperative diagnosis is clinically essential for deciding the strategy of surgical intervention. Some recent imaging characteristics have shown the possibility of preoperative speculation of integrated diagnosis. We introduce our imaging diagnostic approach for posterior fossa pediatric brain tumors. Diffusion-weighted imaging (DWI) has been reported to be a biomarker of tumors because the apparent diffusion coefficient (ADC) obtained from DWI is well inversely associated with tumor cellularity. A high-cellularity tumor such as medulloblastoma showed a low ADC value, whereas the posterior fossa ependymoma (PF-EPN) showed an intermediate ADC value, and pilocytic astrocytoma showed a high ADC value. The WNT medulloblastoma developed at the CP angle and lateral recess of the fourth ventricle, and the SHH medulloblastoma developed in the hemisphere. Groups 3 and 4 medulloblastoma developed midline in the fourth ventricle. Good enhancement was a characteristic of group 3, whereas minimal or no enhancement was a characteristic of group 4 medulloblastoma. PF-EPN-A and PF-EPN-B could be differentiated by their enhancement pattern, that is, poor and good enhancement, respectively. These surrogate imaging markers would be useful for the preoperative diagnosis of pediatric brain tumors. We introduce an imaging diagnostic algorithm for the differentiation of pediatric posterior fossa brain tumors.
