The evaluation of the response to radiation therapy in brain tumor patients is a major and an important issue. Conventional magnetic resonance imaging (MRI) is commonly employed to assess cerebral gliomas after radiotherapy, but it cannot always differentiate tumor regrowth from post-irradiation changes. Magnetic resonance spectroscopy (MRS) is potentially valuable in evaluating changes in cerebral metabolites in patients with a cerebral glioma after irradiation; as it provides valuable information about the metabolism of irradiated gliomas.