With the development of population aging, the incidence of covert stroke gradually increased. Currently, there is still lack of prospective cohort study with large sample size on the relationship between perioperative covert stroke and postoperative cognitive outcomes. The investigators will perform a prospective cohort study. The aim of the study is to determine whether there is an association between perioperative covert stroke and postoperative cognitive outcomes in elderly patients undergoing noncardiac surgery.

Inclusion Criteria:

• Eligible patients were aged ≥60 years and scheduled for elective non-cardiac surgery with general anesthesia, with or without concomitant regional analgesia. They were expected to have surgery lasting at least 2 hours of anesthesia and to stay in the hospital at least 2 days thereafter.

Exclusion Criteria:

• Patients have MRI contraindications, cannot complete the cognitive evaluation, undergo carotid artery surgery or refuse to sign informed consent will be excluded from the trial.

The population will be selected from patients who schedule to receive elective noncardiac surgery in Beijing Tiantan Hospital and Chinese People's Liberation Army General Hospital.