Functional imaging
Functional Imaging(or Functional Medical Imaging), as opposed to structural imaging, centers on revealing physiological activities within a certain tissue or organ by employing medical image modalities that very often use tracers or probes to reflect spatial distribution of them within the body. These tracers often are proportional to some chemical compounds, like glucose, within the body. To achieve this, isotopes are used because they have similar chemical and biological characteristics. By appropriate proportionaliy, the doctors/radiologists(in broader sense) can determine the real intensity of certain substance within the body to evalutate the risk or danger of developing some diseases.