Classics in Neuroimaging: Imaging the Cholinergic System with Positron Emission Tomography.

Since the earliest days of nuclear medicine, there has been interest in using PET and SPECT imaging to interrogate and quantify the cholinergic system. In this Viewpoint we highlight key milestones in the development of cholinergic imaging agents, including identification of radiopharmaceuticals targeting the receptors, transporters, and enzymes of the cholinergic synapse, as well as fundamental developments in the radiopharmaceutical sciences (e.g., cyclotron targetry, radiochemistry) that have enabled translation of the most promising agents into clinical use. We also provide an overview of the current state-of-the-art in cholinergic PET imaging, with an emphasis on radiotracers that are in human studies at PET centers around the world.