The purpose of this study is to test feasibility of a comparative effectiveness framework for acute stroke imaging using prospective electronic health data. This is a prospective, cohort feasibility study of patients presenting to the Emergency Department with suspected acute ischemic stroke. The clinical stroke team will not be blinded to the imaging modality given the nature and purpose of the interventions/imaging. Knowledge of the imaging modality used and the knowledge gained from the resulting data will need to be considered for treatment decisions. Blinding will be maintained for data abstraction and analyses. Analysis will be on an intent-to-scan basis and all qualifying patients will be included in their assigned cohort.