Discuss an imaging profile for thrombolysis patient selection. 

Patients can receive revascularization therapy safely within 24 hours from last known well (LKW) when screened with an appropriate neuroimaging study. 

A 64-year-old man, presented neurological deficits within an hour of symptom discovery and nine hours from LKW. His NIHSS was 19. Brain computed tomography (CT), CT perfusion, and CT angiography demonstrated a large area of ischemic core within the left middle cerebral artery (MCA) vascular territory, and corresponding occlusion of the left internal carotid and left MCA, which did not meet perfusion-based criteria for thrombectomy as the core volume was 131mL. At the time of the patient’s presentation, data on the safety of thrombectomy in patients with large core volumes were not yet published. Given the uncertainty surrounding appropriate treatment, a magnetic resonance (MR) of the brain was obtained to screen for thrombolysis with alteplase, which assesses for the absence of hyperintensity on the fluid-attenuated inversion recovery sequence within the corresponding diffusion-weighted sequence by a signal intensity ratio <1.15. The patient’s ratio was 1.01, thus, he received alteplase. By the time of hospital discharge, the patient could stand independently, intermittently execute complex commands, and walk with a forward rolling walking. 

Our patient’s images highlight that even if a patient has a predicted large core on perfusion imaging, the infarct may not have progressed to hyperintensity on the FLAIR image. The lack of FLAIR hyperintensity despite a large, predicted core aligns with previously published clinical trials demonstrating the benefit of thrombolysis delivery in patients screened by MR for a FLAIR/DWI mismatch and the newly published large core thrombectomy trials that demonstrate that even patients with large cores predetermined on CT imaging or perfusion imaging may have some benefit from thrombectomy up to 24 hours LKW.