CT scan differentiates hemorrhage from ischemia. It detects early signs of infarction in ischemic stroke .The brain CT will rule out the other neurological diseases such as neoplasms, subdural hematoma and vascular malformations that mimic stroke.Perfusional CT provides information about brain perfusion and can help in cases with aneurysms in the brain. CT angiography helps visualize stenosis in both intracranial and extracranial vessels.