Investigator will compare accuracy of transcranial colour coded duplex with CT angiography in detecting arterial obstructions in patients presenting or with history of cerebrovascular ischemic strokes

Cerebrovascular stroke is one of the most common causes of death and disability in the World. It accounts for almost 5% of all disability-adjusted life-years and 10% of all deaths worldwide.

Atherosclerosis is one of the major causes of ischemic stroke, it can lead to cerebrovascular stroke through progressive stenosis, occlusion of the extra or intracranial vessels and or arterio-arterial embolization from an atheromatous plaque.

Intracranial stenosis presents with one or recurrent ischemic strokes and transient ischemic attacks.

High-grade stenosis contributes to both the occurrence and magnitude of ischemic injury.

Overall, 50% of patients have either lacunar, subcortical, or cortical infarction.

The remaining patients with intracranial stenosis have multiple lesions involving a combination of cortical, subcortical, and lacunar infarctions.

There are extensive data about carotid atherosclerosis from American, European and Asian population. However, data from Egyptian ethnics are extremely rare.

Ethnic-racial factors are related to the development of extra- and intracranial atherosclerosis.

Intracranial stenosis causes about 10% of strokes in white people, 20-29% of transient ischemic attacks or strokes in black people, and up to 40-50% of strokes in Asian people.

Extracranial atherosclerosis is common among Caucasian stroke patients. For example, in the United States and Western communities, extracranial carotid artery disease was estimated to be responsible for 20-30% of strokes, while less common in Asian and African populations.

Intracranial arterial stenosis is prevalent in the Egyptian stroke population, similar to most non-white populations.

Transcranial Doppler is routinely performed to assess the blood flow in patients with cerebral ischaemia and provides important real-time information about cerebral haemodynamics.

Transcranial doppler can aid in the diagnostic work-up by detecting, localising and grading the severity of intracranial arterial obstruction.

Transcranial Doppler is an established tool for the non-invasive assessment of cerebral blood flow. Since transcranial doppler results vary with the skills and experience of the sonographer, it requires validation against contrast angiography.

Inclusion Criteria:

• patients who have acute ischemic strokes or transient ischemic attacks .

Exclusion Criteria:

1. Patients with history of cardiac arrhythmia or discovered recently or known rheumatic heart disease.
2. Patients with history of autoimmune diseases.
3. Patients with space occupying lesion or hemorrhage in Ct brain.
4. Pregnant female.
5. Patients who refuse to participate in the study.
6. Patients who have history of allergy or developed acute kidney injury during previous dye injection.
7. Patients who have chronic kidney disease.
8. Premorbid neurological disorder (myopathy, multiple sclerosis) on neurological examination or previous investigations.
9. Inability to achieve safe vascular access.
10. Patients with insufficient temporal acoustic window.

one hundred cases of patients with acute ischemiac cerebrovascular stroke will be included in the study