Positron emission tomography (PET) has been used to try to differentiate between high and low grade gliomas. Gliomas of the posterior cranial fossa can be highly diagnostic on MR imaging in children, but tumors in adults are now used to differentiate between benign and malignant because of structural inconsistencies. In two patients, brainstem biopsies were consistent with PET findings, and one day, PET imaging may be able to outperform biopsy in the diagnosis of dorsal midbrain lesions. Magnetic resonance spectroscopy (MRS) is a noninvasive imaging test that examines tissue characteristics and obtains additional data. Creatine, phosphocreatine, choline, N-acetylaspartate, lactate and lipids are used to analyze different pathological processes. It is used to differentiate between normal and abnormal tissues and levels of brain tumors and also to differentiate between inflammation, infection and tumors. Diffusion tensor imaging (DTI) is a representation of white matter that can represent the relationship between sensation and movement and plays an important role in surgical planning.