Cognitive impairment is a hallmark of many neurodegenerative diseases such as Alzheimer’s disease (AD), Parkinson’s disease and others. Today AD is the most common cause of dementia. This is a disease causing great sufferings to the patient and their relatives and is also an increasing healthcare problem with economical as well as social consequences. AD is a very high cost management disease increasing in an alarming rate in USA. It is very important to diagnose and investigate AD in the early stage that can be helpful both for the patient and for the family. As Acetylcholine (ACh)deficiency is seen in AD, quantifying VAChT (Vesicular Acetylcholine Transporter) levels in the cholinergic nerve terminal predict the ACh levels and may subsequently help in diagnosing AD. This book describes in vitro method to develop a selective and specific PET tracer with suitable characteristics that allow the in vivo study of VAChT levels could be used as a biomarker for studying changes in cholinergic functions in both animals and humans. This book should be especially useful to students, researchers and academicians who are involved in radio tracer development work for diagnosing of AD.