The primary objective of this study is to assess the efficacy of the radiopharmaceutical 3'-deoxy-3'-[F-18]fluorothymidine, [F-18]FLT, a tracor of cell proliferation, using Positron Emission Tomography (PET) imaging for the tumor diagnosis and prognosis in a group of 50 patients with different type of brain tumors.[F-18]FLT PET imaging will be compared to the current used imaging techniques of MRI, spectroscopy imaging, PET imaging using [11C]MET tracer, immunohistochemical analysis and clinical parameters.

Inclusion Criteria:

• adults aged between 18 and 70 years
• must have operable grade II, III or IV glioma, recurrent high grade glioma or brain metastases
• KPS >= 70%
• must have the understanding and ability to sign an informed consent document
• must have adequate liver and kidney function
• be male or non-pregnant, non-lactating females
• patients who are fertile must agree to use an effective method of contraception during participation in the study
• the following laboratory results : absolute neutrophil count >= 1500 cells/µl, platelet count >= 100000 cells/µl, SGOT <= 2.5 x ULN, serum creatinine <= 1.5 x ULN.

Exclusion Criteria:

• contraindication to surgery
• concomitant radio-, chemo-, or immunotherapy
• history of significant dementia
• known diagnosis of Human Immunodeficiency Virus (HIV) infection
• patient with hepatitis B or C