Abstract： Objective:To observe the safety and efficacy of 18F-T807 imaging agent and its biological distribution in Alzheimer′s disease(AD)model mice and normal aging mice. Methods:Twenty specific pathogen free 7-months-old male Kunming mice with body weight of(22±2)g, ten 10-months-old male Tau transgenic(appsw-tau, wild type/hemizygous)mice with body weight of(34±2)g, twenty-five 10-months-old male wild-type C57BL/6J mice with body weight of(28±2)g were selected.Twenty Kunming mice were randomly with the random number table method divided into 4 groups with 5 mice in each group for acute toxicity test.Mice in 3 groups were injected with 3.7 MBq, 18.5 MBq and 37 MBQ 18F-T807 imaging agents diluted by 1 ml normal saline into the caudal vein, respectively.Mice in the fourth group were injected with 1 ml normal saline as the control group.The state and body weight of mice were observed for 14 days.Fifteen wild-type C57BL/6J mice were used for biological distribution experiment, 250 μCi 18F-T807 imaging agent diluted by 200 μl normal saline was injected into the body through the tail vein, and 500 μl blood was taken from the eyeballs at 5, 15 and 30 minutes after administration, and the mice were killed.The plasma and red blood cells were separated, and the heart, liver, spleen, lung and kidney were weighed, and the percentage of radioactive uptake per gram of tissue was calculated.Tau transgenic(APPSW-Tau, wild-type/semi-zygous)mice were used as AD model mice, and wild-type C57BL/6J mice were used as normal aging mice, 10 in each group.GE SIGNA positron emission tomography(PET)/MRI Scanner was adopted for 18F-T807 PET/MRI body imaging. Results:The results of acute toxicity test showed that 18F-T807 imaging agent had no adverse effect on the growth of mice at the maximum tolerated dose.The results of biological distribution showed that 18F-T807 was rapidly cleared from the brain, and renal excretion was an important pathway.PET/MRI imaging results of AD model mice and normal aging mice showed that the radioactive accumulation in the brain of AD model mice was higher than that of normal aging mice, but the difference was not statistically significant( P=0.142). Conclusions:The imaging agent 18F-T807 is safe and effective.The imaging agent is metabolized by digestive and urinary systems and can rapidly penetrate the blood-brain barrier and quickly elute in normal and transgenic dementia mice.