Biodistribution, Pharmacokinetics, and Safety of F-18 THK-5351 PET in Alzheimer's Disease Patients and Healthy Subjects.(Positron Emission Tomograph )

Healthy Inclusion Criteria: * Neurologic testing. (MMSE 24-30, Wechsler Logical Memory score \>5). * Subjects must provide written inform consent. Patients with AD Inclusion Criteria: * Diagnosis of AD according to the clinical diagnostic criteria of "possible AD" with NINCDS-ADRDA criteria * MMSE 20-26, Clinical dementia rating 0.5 or 1, Wechsler Logical Memory score\<=4 * Patient who provide a written informed consent prior to study entry. (If the patient is incapable informed consent, the caregiver may consent on behalf of the patient. The caregiver should be able to report activities of daily living and their mental status.) Exclusion Criteria: * Pregnant or become pregnant * Current breast feeding * Clinically significant abnormal laboratory values * Unstable medical or psychiatric illness. * Cardiovascular disease (cardiac surgery or myocardial infarction within the last 6 months; unstable angina; decompensated congestive heart failure; significant cardiac arrhythmia; congenital heart disease). * History of drug or alcohol abuse within the last year, or prior prolonged history of abuse. --History of severe allergic or anaphylactic reactions particularly to the tested drugs . * PI assessment with high risk.