-the right begin at bifurcation of the brachiocephalic artery.
-the left comes from the highest part of the arch of the aorta.
Each common carotid artery divided into:
External carotid artery : which supply the exterior of the head ,the face and the greater part of the neck.
Internal carotid artery: which supply the remaining part of the head within the cranial and orbital cavities.
1-Patient is supine with head turned slightly away from the side being examined.
2- Both patient and sonographer must be comfortable because the examination takes 20-30 min .
Carotid sonography requires:
Grey scale: is used to detect and evaluate the appearance of carotid plaque.
Colour Doppler: is used to identify vessels, blood flow, plaque and carotid wall thickening.
Spectral Doppler: this allows measurement of blood flow velocity and to evaluate stenosis.
Should be kept at <60 degrees to minimize measurement error.
Longitudinal image and bifurcation :