Background and purpose: In adult, the half of the CNS neoplasms are metastatic, and high grade astrocytomas and oligodendrogliomas are most frequent malignant tumors among the last half. Recently, integrated MRI-PET (Biograph mMR, Siemens, Germany) was introduced, and can provide simultaneous whole body MRI-PET imaging as well as brain-specific advanced imaging (e.g. DWI, PWI, and DCE). The purpose of the present study is to evaluate whether the simultaneous MRI-PET acquisition can improve the diagnostic yield for the patients initially presented with brain tumors, and predict the prognosis in the patients diagnosed with primary high graded astrocytoma or oligodendroglioma.

Materials and methods: Simultaneous MRI-PET (FDG) will be prospectively obtained in patients (n = 60) initially presented with brain tumors by using integrated MRI-PET (Biograph mMR, Siemens, Germany). We will exclude the patients suspected to have benign brain tumors such as meningioma and schwannoma on previous imaging studies. We will use the imaging protocols including whole body MRI-PET and advanced brain tumor imaging (DWI, PWI and DCE). In addition, we will analyze the imaging parameters to see whether the enrolled tumors are primary brain tumors or metastatic, and evaluate the tumor grading efficiency and prognosis prediction for the patients with high grade astrocytomas or oligodendrogliomas.

Expected results: We expect that whole body MRI-PET is useful for the differential diagnosis of primary and metastatic brain tumors, and the multiparametric information from DWI, PWI, DCE and PET can be used for the tumor grading and prognosis prediction of the primary brain malignancies.

Inclusion Criteria:

• We will inculude the enrolled tumors are primary brain tumors or metastatic, and evaluate the tumor grading efficiency and prognosis prediction for the patients with high grade astrocytomas or oligodendrogliomas.

Exclusion Criteria:

• We will exclude the patients suspected to have benign brain tumors such as meningioma and schwannoma on previous imaging studies.

primary brain tumors or metastatic, and evaluate the tumor grading efficiency and prognosis prediction for the patients with high grade astrocytomas or oligodendrogliomas.