Proton Magnetic Resonance Spectroscopy: Virtual non invasiveexploration for the biochemical characterization of brain tumors.

Proton Magnetic Resonance Spectroscopy (MRS) is a noninvasive technique that could be describe as a virtual biopsy used to evaluate the biochemical content of the brain, providing additional metabolic information to anatomic changes that can be evident on Magnetic Resonance Imaging (MRI) studies. The aim of this study is to characterize the metabolic pattern of most common brain tumors based on the spectroscopic markers that best differentiate between them using the technique of Multivoxel MRS. 20 patients (5 of each type) with diagnosis of Glioblastoma Multiforme, Glioma, Pilocytic Astrocytoma, and Brain Breast Metastasis were studied. MRI and MRS were performed on a 3-Tesla scanner (Signa Excite, General Electric®). Multivoxel MRS was performed using the PRESS sequence (Point Resolved Spectroscopy Sequence). Data were tabulated and expressed as Cho/Cr, NAA/Cr, Lac/Cr and Lip/Cr ratios. They were statistically analyzed using Analysis of Variance (ANOVA) and Student-Neuman- Keuls test for multiple comparisons among means. The results obtained allow us to conclude that the elevation of Cho/Cr together with the decrease in NAA/Cr suggests a higher degree of aggressiveness or malignancy of the tumor while an increase of Lac/Cr and/or Lip/Cr indicates an important degree of necrosis and anaerobic metabolism of glucose.