Objective: To determine the frequency of incidental acute or subacute cerebral infarction (CI) in a population-based study. Patients and Methods: We identified 2095 participants aged 50 to 98 years in the population-based Mayo Clinic Study of Aging from October 23, 2009, to October 5, 2016, with a usable diffusion tensor imaging (DTI) sequence (total scans=3230). Acute and subacute infarcts were identified by neuroradiologists. For each participant, vascular risk factors, medications, clinical symptoms, and neurological examination near the time of the CI were abstracted from the medical record. The probable etiologic mechanism for the CI was determined. Results: Nine CIs were identified with a frequency of 0.28% among individual magnetic resonance imaging (MRI) scans and 0.43% among unique individuals. Infarctions were detected in 0.097% of scans from participants younger than 70 years and in 0.36% of scans of those 70 years or older. Six CIs were acute, and 3 were subacute. Most participants with infarcts were men (78%), with a mean age of 76.9±6.74 years. All were asymptomatic at the time of CI detection. The probable mechanisms of CI were small vessel (n=6), cardioembolic (n=2), and cryptogenic (n=1). Conclusion: Acute and subacute cerebral infarcts occur as incidental findings in approximately 1 in 230 people aged 50 to 98 years, particularly in elderly men and those with vascular risk factors. As brain MRI becomes more widely used, incidentally detected acute or subacute infarcts will provide an opportunity to improve stroke prevention.
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