Nuclear Imaging is an imaging technique involving the application of radioactive pharmaceutical in the diagnosis of disease. Nuclear imaging can be used to diagnose a wide range of conditions. The patient will inhale, swallow, or be injected with a radiopharmaceutical. Radiopharmaceutical is a radioactive material. After taking the substance, the patient will normally lie down on a table, while a camera takes pictures. The camera will focus on the area where the radioactive material is concentrated. This will show the doctor what kind of a problem there is, and the location of it. The main advantage of a Nuclear Imaging examination is the possibility to obtain excellent and unique information about the examined organ’s function. It offers good complementarity beside X-ray and MRI modalities, which display better anatomical images. In this context, functional imaging means that we can get information on the metabolism of an organ or a system. This way, a dysfunction (hyper- or hypo- metabolism) offers information not otherwise observed on morphological images, leads to more precise characterization of the tissues and enables differentiation between benign and malignant lesions. Types of imaging techniques include positon emission tomography (PET) and single-photon emission computed tomography (SPECT). PET and SPECT scans can provide detailed information about how a body organ is functioning. Besides that PET and SPECT can show the proggression of a treatment and the effectiveness of treatment. PET and SPECT are also offering new insights into psychiatric conditions, neurological disorders and addiction.