Functional studies in brain and heart with positron emission tomography.

Positron Emission Tomography (PET) has evolved in the last years into a powerful research technique for the study of the physiology and pathophysiology of the human brain in vivo. These procedures now need no longer be viewed only as research studies. They are ready to be applied clinically on a wide scale. This article will give a short overview of the technical and methodological background and outline the clinical research applications by using the most developed tracers in the field: glucose and its analogs, oxygen, fatty acids, various perfusion markers and receptors, all labelled with positron emitting isotopes. They allow the quantitative measurement of local tissue functions in an essentially non-invasive way.