ABSTRACT
Single-photon emission computed tomography (SPECT) and positron emission tomography (PET) are both well-established emission tomographic imaging methods used in clinical diagnosis and in research. Both are tomographic imaging methods that allow for in vivo studies of physiological processes by observing the distribution of the concentration of a radiotracer within the subject that is being studied. The radiotracers used are substances that are part of the normal physiological processes in the body, with the difference that they are labeled with a radionuclide that can be detected by external means. For instance, glucose metabolism can be studied by following the distribution of fluorodeoxy glucose labeled with 18F (18FDG), which emits a positron. The formation of skeletal tissue can be studied using methylene diphosphonate (MDP) labeled with 99mTc, which is a gamma emitter.
