CT perfusion (CTP) of the brain is an innovative technique to identify rapidly regions which are only partially or insufficiently perfused during an acute ischemic event. The differentiation between the core infarct and the still viable penumbra is its major clinical application. CTP helps directly in the decision-making process in the event of acute ischemic stroke by increasing the potential of success in patient who can benefit from thrombolytic/endovascular treatment.

The use of CTP in patient selection for thrombolytic/endovascular treatment was never evaluated in a prospective randomized study. Yet, clinical experience well demonstrated a good correlation between the size of the penumbra and the clinical outcome when done in early as well as late stages of the event.

The importance of identifying the penumbra in the acute phase of the ischemic stroke is widely accepted. But crucial evidence to support the predictive value of CTP to predict the clinical and anatomical/structural outcomes in the late phases (90 days after) is lacking.

Currently, the use of CTP is based on theoretical assumptions and expert opinions but a randomized prospective study to validate its use is lacking.

The current guidelines restrict the use of CTP trials and to patients that can't performed MRI scan.

Inclusion Criteria:

• NIHSS>=8
• up to 6 hours from event onset

Exclusion Criteria:

• mRS>= 3 before the start of the event
• life expectency <1 year because other disability disease

men and women admittedto the emergency room at Rabin Medical Center, Beilinson Campus and hospitalized at the neurology department.