ABSTRACT
Positron emission tomography (PET) can assess a broad range of functional parameters such as metabolic activity (e.g. glucose metabolism), cerebral blood flow (CBF), neurotransmitter activities and receptor binding, measured with high accuracy. A quantification and three-dimensional imaging of distinct physiological variables are obtained which make PET a powerful tool for the evaluation of brain function in normal and disease states. In the PET procedure, a positron-emitting compound synthesized by a cyclotron is administered systemically and is then taken up by the brain, where it releases positrons (positively charged electrons) which collide with electrons which are annihilated, releasing two gamma rays at 180 to each other. A ring of radiation detectors surrounding the head is used to measure the location of radioactivity within the brain.
