that we would just do CT scans and a CT scan doesn't show up the stroke usually 4 6 8 10 hours it's too late so we want to see the stroke as it's developing so with this technique you can see this pink area is the tissue that is irreversibly injured it's dead but the green area is the tissue that's likely to die over the next several hours so if a patient comes in like this one at six hours after symptom onset and they have a small amount of tissue that's are irreversibly injured but a large amount that is still salvageable