 Background: Central nicotinic acetylcholine receptors nAChRs mediate a variety of brain functions and have been implicated in the pathophysiology of Alzheimers and Parkinsons diseases, other CNS disorders Tourettes syndrome, epilepsy, etc., and nicotine dependence. These receptors are the primary target for the action of nicotine, which is believed to cause tobacco dependence. The ability to quantitatively image nAChRs with PET in humans would allow scientists to monitor the nAChRs in vivo during nicotine dependence and smoking cessation and to determine the receptor occupancy by nicotine for different types of nicotine replacement therapy NRT. Recently completed studies demonstrated the feasibility of imaging nAChRs in the human brain with 218FFA-85380 and showed that each participant could receive up to 4 injections of 5 mCi70 kg without exceeding dosimetry limits imposed by the FDA and the NIH Radiation Safety Committee. 