الفهرس 
Pathology of pediatric brain tumorsOnly 14 pages are availabe for public view
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Abstract
Proton magnetic resonance Spectroscopy (1HMR spectroscopy) is a noninvasive technique that is acquiring an important role in the diagnosis of brain tumors before surgery. This technique provides metabolic information regarding the tissue being studied that complements the anatomic information obtained with conventional magnetic resonance imaging
Conventional Magnetic resonance imaging (cMRI) and magnetic resonance spectroscopy (MRS) rely on the same physical principles to collect signal but differ in the way the data is processed, displayed, and interpreted. Instead of images (obtained in cMRI), a plot with peak amplitudes compared with a respective frequency is obtained in MRS.
The routine metabolites identified with short and long TEs include; N-Acetyl aspartate (NAA), Creatine (Cr), Choline (Cho), Lactate (Lac). The additional metabolites identified only with short TE include; Lipids (Lip), Glutamine and glutamate (Glx), Myo-inositol (ml).
The spectral pattern of pediatric intracranial tumors usually includes reduction in N-acetyl aspartate (NAA) level and NAA/Creatine (Cr) ratio, decreased creatine (Cr) level, Increase in Choline (Cho) and Cho/NAA and Cho/Cr ratios, also higher Lactate peak is seen in higher grade tumors, and the presence of lipids is a strong indication of tissue necrosis. ml/Cr ratio is usually higher in lower grade than in higher grade tumors.
MRS may have an important role to play in guiding the surgeon to the area of highest abnormal spectral changes in the brain lesion prior to stereotactic surgery for histological diagnosis and tumor staging. As multivoxel spectroscopy accesses the lesion in its complete extension and is able to identify the area with the greatest increase in Cho levels, hence greater tumor activity, which is the ideal site for biopsy.