Receptor imaging by positron emission tomography and single-photon emission computed tomography

Positron emission tomography (PET) has been used primarily to measure regional brain metabolism and blood flow. Single-photon emission computed tomography (SPECT) also can be used to measure brain perfusion. Receptor imaging by PET and SPECT, however, offers distinctive advantages over the more established flow/metabolism imaging methods, including improved chemical specificity and improved sensitivity in detecting changes in disease. Radioligands are available for PET and SPECT imaging of many neuroreceptors, including the opiate receptor, the dopamine receptor, and the muscarinic cholinergic receptor. A new focus of interest is the imaging and quantification of presynaptic neurotransmitter reuptake sites.