الفهرس 
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Abstract
This study was conducted on twenty patients in the pediatric age group with suspected or diagnosed brain tumors. They were seven males and thirteen females. Their age ranged between two years and 18 years with a median age of nine years.
The aim of this work is to study the role of proton magnetic resonance spectroscopy in evaluation of pediatric brain tumors.
All patients were subjected to full history taking and thorough clinical examination. Magnetic resonance imaging was performed at 1.5 Tesla MR system using a standard head coil. Imaging included conventional MRI and proton magnetic resonance spectroscopy. Proton magnetic resonance spectroscopy was done using either single or multi-voxel technique.
In the present study, there were 7 patients with pilocytic astrocytoma, 5 patients with diffuse intrinsic pontine glioma, 4 patients with medulloblastoma, one patient with ependymoma, one patient with anaplastic astrocytoma, one patient with tectal glioma and one patient with medulloepithelioma. Histopathological correlation was done in 16 patients; while three patients with diffuse intrinsic pontine glioma (DIPG) and the patient with tectal glioma were managed based on clinical and MR imaging features.
By using magnetic resonance spectroscopy, we found that the common pediatric brain tumors; pilocytic astrocytoma, medulloblastoma and ependymoma had specific metabolic profile that can be used to differentiate between them. We also were able to differentiate between non-neoplastic and neoplastic lesions, between radiation necrosis and tumor residual/recurrence and detect tumor tissue beyond the enhancing tumor bed.
The spectrum of pilocytic astrocytoma revealed high Cho/NAA and Cho/Cr ratios, relative low concentration of creatine with increased NAA/Cr ratio. Lactate doublet was detected in all cases while no lipids peaks were detected.
The spectrum of anaplastic astrocytoma revealed increased both Cho/NAA and Cho/Cr ratios, while decreased both NAA/Cho NAA/Cr ratios with no lipids peak. Peritumoral infiltration was noticed as metabolic abnormalities in the peri-lesional area outside the enhancing tumor bed.
The spectrum of diffuse intrinsic pontine glioma revealed increased both Cho/NAA and Cho/Cr ratios. Lactate doublet was detected in three patients, while lipids peaks were also detected in three patients.
The spectrum of medulloblastoma revealed very high Cho/NAA and Cho/Cr ratios, with low Cr/Cho reflecting the very high concentration of choline in this highly cellular tumor. Taurine peak was detected in two patients while lipids peak was observed only in one patient.
The key features of the spectrum of ependymoma were relatively increased Cr/Cho with prominent myo-inositol peak.