Inclusion Criteria:  Chinese men and women are included age between 18-40 years Normal vital signs and physical examination No clinical abnormalities in ECG, EEG, and echocardiogram No past history of cardiovascular, cerebrovascular, or gastrointestinal diseases Normal or no clinical significance abnormalities in laboratory tests No any other major or chronic illness No presence of drug use Females adopt effective medically approved contraceptive methods to prevent pregnancy for at least 6 months before the study and after the study Voluntarily agree and signed written consent  Exclusion Criteria:  Previous history of cardiovascular diseases A history of or physical or radiographic manifestations of any previous brain disease Any previous major disease or unstable condition Subjects who cannot complete XTR004 imaging as required Positive HIV, hepatitis C or Treponema pallidum antibody and hepatitis B surface antigen detection A history of coagulation or coagulation disorder A history of liver or gastrointestinal disease or other conditions that interfere with drug absorption, distribution, excretion or metabolism as determined by the investigator Previous history of cancer High risk of drug allergic reaction A history of alcohol or drug abuse/dependence Exposure to significant occupational radiation (e.g >50 mvs/year) or exposure to radioactive substances for therapeutic or research purposes over the past 10 years Scheduled surgery or other invasive interventions within one week before drug injection Subjects use any drug or treatment that may interfere with the experimental data or cause serious side effects, as determined by the investigator Pregnant or lactating women Admitted to hospital due to illness during screening period Other conditions that investigators consider inappropriate to participate in a trial.