What Is a Carotid Ultrasound?
The brain uses glucose as its major energy source. It is supplied by the paired (left and right) carotid arteries which originate from the aortic arch. The brain uses a disproportionate amount of glucose compared to the rest of the body, so the flow of blood through the carotid arteries must not be compromised if cerebral perfusion is to remain normal. Atherosclerosis, the deposition of plaque on the arterial walls, is a systemic disease that affects arteries throughout the body. Atherosclerosis of the carotid arteries can result in symptoms of ischemia from blockage; thrombus formation can also develop over the atherosclerotic lesion with the risk of separation and embolism that will cause transient ischemic attacks (TIA) or stroke.
There is collateral blood flow where the left and right circulations ultimately mix in the brain at the circle of Willis, and this protection from compromised flow in one of the carotid arteries depends on the adequacy of this collateral circulation
Duplex ultrasound, the combination of B (“brightness” mode) for structure and Doppler assessment of blood flow, offers the least invasive method for both screening for carotid disease as well as for an initial approach to diagnosis.
The B mode takes advantage of the different tissue densities that reflect back high-frequency sound waves to construct a picture of arterial structure and plaques within, while the Doppler ultrasound bounces sound waves from red blood cells to depict blood flow.
There are several ways to image the internal environment of the carotid arteries, but ultrasound offers the safest, easiest, and least expensive.