Does imaging of the ischemic penumbra have value in acute ischemic stroke with large vessel occlusion?

Purpose of review In this review, we summarize current evidence regarding potential benefits and limitations of using perfusion imaging to estimate presence and extent of irreversibly injured ischemic brain tissue (‘core’) and severely ischemic yet salvageable tissue (‘penumbra’) in acute stroke patients with large vessel occlusion (LVO). Recent findings Core and penumbra volumes are strong prognostic biomarkers in LVO patients. Greater benefits of both intravenous thrombolysis and endovascular therapy (EVT) are observed in patients with small core and large penumbra volumes. However, some current definitions of clinically relevant penumbra may be too restrictive and exclude patients who may benefit from reperfusion therapies. Alongside other clinical and radiological factors, penumbral imaging may enhance the discussion regarding the benefit/risk ratio of EVT in common clinical situations, such as patients with large core – for whom EVT's benefit is established but associated with a high rate of severe disability –, or patients with mild symptoms or medium vessel occlusions – for whom EVT's benefit is currently unknown. Beyond penumbral evaluation, perfusion imaging is clinically relevant for optimizing patient's selection for neuroprotection trials. Summary In an emerging era of precision medicine, perfusion imaging is a valuable tool in LVO-related acute stroke.