Inclusion Criteria1. Patient with acute cerebral ischemia due to ICA or MCA occlusion,
2. Patient already enrolled in the NIH FAST-MAG clinical trial,
3. Patient's clinical attending physician plans mechanical embolectomy procedure as part of routine clinical care.
4. Age 40-95 inclusive (age criteria for FAST-MAG Trial).
Exclusion Criteria1. Technical inability to navigate microcatheter to target clot.
2. Patient or surrogate unavailable for consent