Abstract: PET is an advanced imaging technology to obtain biological, physiological or pharmacological function.The PET signal comprises the sum of a radio-probe and its radioactive metabolites from intracellular, extracellular and intravascular compartments of a given tissue, it cannot provide the chemical composition of the radioactivity or compartments of radio-labeled substances present.On the other hand, in vivo microdialysis is a powerful sampling technique wherein regional chemical information is obtained by implantinga probe into the extracellular fluid of interest tissue.Combined PET and microdialysis may potentially play an important role in pathophysiology, pharmacology, pharmacokinetics and drug metabolism.