[Positron emission tomography as a quantitative imaging method for demonstrating regional brain metabolism].

By means of positron emission tomography (PET) the distribution of certain isotopes in transverse sections through the body is visualized and the concentration of labelled tracers in the tissue quantified. Various biochemical and physiological processes in the brain can be followed by positron emitting radionuclides and compounds labelled thereby. Of these methods the measurement of glucose metabolism with 18fluorodeoxyglucose, of oxygen consumption with 15oxygen and of blood flow with 15O-carbon dioxide or 18fluoromethane are of greatest clinical relevance. These techniques demonstrated increases in metabolic rate after functional activation of respective brain regions and revealed local metabolic disturbances after different pathological changes of the central nervous system. With other labelled compounds protein synthesis, distribution of specific receptors, damage of the blood brain barrier, blood volume and regional uptake of drugs can be studied. PET thereby provides an insight in the biochemistry and the function of the brain which is at present not feasible with any other technology.