Oligemia, Penumbra, Infarction: Understanding Hypoperfusion with Neuroimaging.

Despite recent progress in the treatment of acute ischemic stroke with multiple trials demonstrating improved clinical outcome associated with endovascular thrombectomy up to 24 hours after onset, there is potential opportunity for optimal patient selection and treatment algorithm to further improve treatment outcome. Current limitation is in part caused by inconsistency of imaging protocols and imaging-based definitions of oligemia, penumbra, and infarction core within the various hypoperfusion states. To truly maximize the impact of imaging in acute ischemic stroke, imaging definitions of hypoperfusion states need to be more consistent and validated to correctly reflect different severities of ischemic injury.