[18F]AV45(Aβ) and [18F]AV1451(Tau)PET/CT in the Diagnosis of Early Pathological Changes of Alzheimer's Disease

Inclusion Criteria: * Meet the MCI diagnostic criteria of Peterson in 2004; * The clinicaldementiarating Scale (CDR) score was 0.5; * Prominent memory loss may also be accompanied by impairment of other cognitive domains; * Insidious onset and slow progression; * Not at the level of dementia. AD entry criteria: * Meet the criteria for diagnosing dementia as described in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-R), Use the diagnostic criteria for AD from the National Institute of Neurology, Speech and Communication Disorders and Stroke - Alzheimer's Disease and Related Disorders (NINCDS-ADRDA) or the National Institute on Aging and Alzheimer's Disease Association (NIA-AA). * Clinical Dementia Rating Scale score was 1 point. Exclusion Criteria: * Patients with a history of stroke and focal neurological signs, and imaging findings consistent with small cerebral vascular disease (Fazekas score ≥2); * The presence of other neurological disorders that can cause brain dysfunction (e.g., depression, brain tumors, Parkinson's disease, metabolic encephalopathy, encephalitis, multiple sclerosis, epilepsy, brain trauma, Normal facial pressure hydrocephalus); * The presence of other systemic diseases that can cause cognitive impairment (such as liver insufficiency, renal insufficiency, thyroid dysfunction, severe anemia, folic acid or vitamin B12 deficiency, syphilis, HIV infection, alcohol and drug abuse, etc.); * There is mental and neurological retardation. * There are other diseases that are known to cause cognitive impairment.