Cerebral Small Vessel Disease and Perioperative Covert Stroke

Inclusion Criteria: * Age from 65 years to 85 years; * The patient is about to have major surgery for the first time and the operation is non-cardiac surgery; * Written informed consent is obtained before the surgery. Exclusion Criteria: * mental illness; * Already have other diseases that can cause dementia, such as Alzheimer's disease, Lewy body dementia, Frontotemporal dementia, progressive supranuclear palsy, Parkinson's disease, Creutzfeldt-Jakob disease, Huntington's disease, alcohol and drug dependence, Neurosyphilis, systemic lupus erythematosus; or preoperative MRI shows hippocampal and temporal lobe atrophy more than two levels, suggesting the possibility of Alzheimer's disease * Have suffered from other brain diseases (such as stroke, multiple sclerosis, central nervous system infection with sequelae, etc.); * Preoperative MRI indicates covert stroke * MMSE or MoCA scale cannot be completed due to other reasons (such as hearing impairment or visual impairment) * MRI contraindications before or after surgery or patients who cannot tolerate MRI imaging * Stage 3 or 4 malignant tumors, and high malignancy and poor prognosis cancer, such as pancreatic cancer, gallbladder cancer, and bile duct cancer.