Abstract: Objective To explore the changes of metabolites in brain gliomas before and after radiotherapy with magnetic resonance spectroscopy（MRS）.
Methods Thirty-one patients with brain gliomas confirmed by pathology after partial surgical resection were underwent routine MRI，contrastenhanced MRI and MRS before and after radiotherapy in a week. The regions of interest（ROI）were placed on the central enhancement region， peritumoral brain edema region and normal white matter region， respectively. The metabolic distribution of each ROI were obtained using GE AW Functool software. The ratios of Cho／Cr，Cho／NAA and NAA／Cr were calculated automatically.
ResultsCompared to preradiotherapy（pre-RT）， the values for Cho and NAA increased after radiation therapy（post-RT） in the enhancement region. The difference in NAA values between preTR and post-RT showed statictical significance（39.295±33.778 vs. 56.062±39.031, P=0.02）， while no significant differences in Cho changes. In peritumoral edema region， Cho declined and NAA values increased post-RT， with no statistical significance for Cho and NAA between pre and post-RT. Compared to pre-RT， the ratios of Cho／Cr，Cho／NAA and NAA／Cr decreased in regions of enhancement and peritumoral edema post-RT. There were significant differences in Cho／Cr and no significant differences in Cho／NAA，NAA／Cr between pre and postRT for both 2 regions. Conclusion MRS shows early changes of metabolism in enhancement and peritumoral edema regions post-RT， which can early reflect the efficacy of radiotherapy.