Primary brain tumor imaging biomarkers: A review of currently available PET and MR techniques.

Learning Objectives 1. Review of currently available PET and MR biomarkers for diagnosis, grading, treatment planning and response assessment of primary brain tumors. 2. Review the applicability of PET/MR modality for assessment of brain tumors.

Major improvements have been made in treatment of brain tumors by improvements in neurosurgical techniques, radiation therapy procedures and emergence of target drugs. Therefore, there is a need for quantitative and reproducible assessment of disease progression and treatment response. MRI is extensively used not only for localization of tumor, but also for characterization of the brain lesions. The information acquired by various MR sequences is able to provide details about the cellularity, pattern of growth, vascularity and necrotic composition and status of blood brain barrier. The wide variety of different radiopharmaceuticals in molecular imaging has opened the way for extensive research in brain tumor imaging by targeting biological pathways, tumor angiogenesis, proliferation of cell, hypoxia and immune response. 1. PET radiopharmaceuticals used for imaging brain tumor a. 2-deoxy-2-[18F]fluoro-D-glucose (18F-FDG) b. Radiolabelled amino acids c. Hypoxic Agents d. Somatostatin Receptors e. Tumor angiogenesis 2. MR techniques for brain tumor imaging a. Conventional sequences b. Diffusion weighted imaging c. Diffusion Tensor imaging d. Perfusion weighted imaging e. MR Spectroscopy 3. Combination of PET and MR