Glioma is one of the most malignant tumors due to its special construction of the glia cells and its character of infiltration. The usual procedure of the treatment is the surgical resection followed by radiotherapy with or without chemotherapy. This combined treatment needs the precise information on the extent of the tumor's infiltration and tumor grading, and then the determination can be made as to when, where and what kind of treatment should be used. Functional imaging modalities display advantages in defining the heterogeneous characters and histological grade. This paper describes how the ratios of Cho/NAA and Lac/NAA measured by magnetic resonance spectroscopy imaging (MRSI) could be used to define the cancer cell distribution in tissues, tumor burden and malignancy, and the results are proved to be consistent with the histological observation.