Alzheimer’s disease is the most common form of dementia, affecting 25 million people worldwide. Diagnosis has traditionally been difficult, based solely on clinical examination and medical history. In this video, Lawrence Saperstein, MD, a radiologist in the Department of Radiology & Biomedical Imaging at Yale Medicine, explains how positron-emission tomography (PET scanning) has completely revolutionized the evaluation process. PET Scanning uses radioactive material and a special camera to evaluate organ and tissue function. It gives doctors the ability to diagnose Alzheimer’s disease earlier than was previously possible.