Neuroimaging is a key tool in the diagnosis and follow-up of neuro-oncologic patients. Magnetic resonance imaging (MRI) and computerized tomography (CT) are the main imaging modalities involved in neuroimaging diagnosis. These two imaging modalities are different regarding imaging acquisition principles and techniques. One of the main differences between them is that CT uses ionizing radiation for imaging acquisition while MRI uses a magnetic field. MRI imaging also has the advantage over CT as it demonstrates significantly more details of the tissues and the anatomy of the brain. Therefore, because of the risks related to radiation exposure and lack of additional information as compared to MRI, CT is a less attractive method to image the head.PET (positron emission tomography) and molecular imaging are rapidly developing as new techniques to evaluate brain tumor. The results provided by PET and molecular imaging appear to corroborate the findings of MRI studies and may contribute to decision-making in the treatment and follow-up of patients. Therefore, understanding general principles of imaging acquisition and interpretation can help the clinician to improve patient care.The aim of this chapter is to describe standard MRI and CT imaging acquisition techniques, basic principles of imaging interpretation, as well as radiation safety principles. New imaging techniques will also be visited together with the influence that these may have on day-to-day practice in the future.