Positron emission tomography (PET) involves the intravenous injection of positron-emitting radionucleotides which are tagged to various brain metabolites. A cyclotron is required to generate these positron-emitting isotopes that can be made from a variety of biologically interesting compounds.
Positron-emitting radioisotopes decay by emission of positrons or positively charged electrons. These quickly combine with an adjacent electron in an annihilation reaction with the emission of two high energy gamma rays in opposing directions. Their presence in the brain is detected by a sophisticated scanning device. Recording of these simultaneously emitted photons allows calculation of their site of origin and, therefore, a map of radiopharmaceutical distribution in the patient. Computerized tomography (CT) analysis produces an accurate measurement of the radioactivity emitted from each pixel. This is displayed as a two-dimensional color-coded image.
PET can be used to study...
References and Readings
- Saunders, D., Jager, H., Murray, A., & Stevens, J. (2008). Functional imaging techniques. In R. Grainger & D. Allison (Eds.), Grainger and Allison’s diagnostic radiology: A textbook of medical imaging (5th ed., pp. 1255–1256). London: Churchill Livingstone.Google Scholar