the study will be carried out to standardize normal parameters of vascular duplex ultrasound of the cranial vessels in the Egyptian population.

Atherosclerosis is a major cause of ischemic stroke and a significant proportion of strokes are thromboembolic in nature, arising from atherosclerotic plaques. Several studies have reported racial differences in the severity and distribution of carotid atherosclerosis. In the United States and Western communities, Extra-cranial carotid artery disease was estimated to be responsible for 20-30% of strokes. Little is known about the prevalence and distribution of carotid disease among the populations in the developing countries.

Vascular duplex ultrasound is a useful, cheap and available diagnostic tool for assessing cranial vascular disease. Duplex ultrasound can be highly reliable with proper technique, without the risk of radiation in other imaging modalities, is well tolerated by all patients including those who are claustrophobic in MRI machines, and has much less risks compared to conventional angiography studies.

Although vascular duplex has been used for years yet there is little researches had been done on normal population in the developing countries to collect results and compare it to the parameters that was collected and reviewed in the western developed populations.

The parameters that would be used in this study include both the data collected by static and dynamic duplex scan which are the intimal-medial thickness, the vessels' diameter, peak flow velocity and peak flow volume both systolic and diastolic for either extra- or intra-cranial vessels.

Inclusion Criteria:

• Normal subjects between 20-40 years

Exclusion Criteria:

• Diabetic patients, hypertensive patients, any evidence of vascular disease either peripheral or central, subjects refusing to participate

Egyptian population