Grade 0 - No perfusion

Grade 1 - Antegrade reperfusion past the initial occlusion, but limited distal branch filling with little or slow distal reperfusion

Grade 2a - Antegrade reperfusion of less than half of the occluded target artery previously ischemic territory (eg, in 1 major division of the MCA and its territory)

Grade 2b - Antegrade reperfusion of more than half of the previously occluded target artery ischemic territory (eg, in 2 major divisions of the MCA and their territories)

Grade 2c - Near complete perfusion except for slow flow or distal emboli in a few distal cortical vessels*

Grade 3 - Complete antegrade reperfusion of the previously occluded target artery ischemic territory, with absence of visualized occlusion in all distal branches