Role of proton magnetic resonance spectroscopy in diagnosis of pilocytic astrocytoma in children

Background: Pilocytic astrocytomas are the second overall most common pediatric brain tumor. Magnetic resonance (MR) imaging is widely used in the diagnosis and follow up of pediatric patients with pilocytic astrocytomas because of its ability to provide anatomical detail. However conventional MR imaging does not provide information about tissue biochemistry. Aim of the work: To study the role of proton magnetic resonance spectroscopy in diagnosis of pilocytic astrocytoma in children. Subjects and methods: This study included seven pediatric patients with histopathologically proven pilocytic astrocytoma. All patients were subjected to full history taking and thorough clinical examination. Magnetic resonance (MR) 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. Surgical biopsy was then performed to all patients and correlation with histopathological data was done. Results: Out of the seven patients included in this study, six were females and one was male with mean age of 9.5 years, the tumor was located in five of them in the posterior fossa, located in right thalamo-peduncular region in one patient and located in the hypothalamic–chiasmatic region in one patient. MR spectroscopic study showed the same findings in all the lesions including high Cho/NAA and Cho/Cr ratios (3.53 ±1.5) and (7.21 ± 4.2), respectively, relative low concentration of creatine with increased NAA/Cr ratio (2.32 ±1.1). Lactate doublet was detected in all cases while no lipid peaks were detected. Conclusion: Based on the findings in this study we suggest that pilocytic astrocytoma has a specific spectroscopic metabolic profile which could be diagnostic for this type of tumor.