Sonographic Examination of the Carotid Arteries
What are the symptoms of a blockage in the carotid artery?
Why is carotid Doppler test done?
Can ultrasound detect plaque in arteries?
How long does it take to do a carotid artery ultrasound?
Carotid ultrasound uses sound waves to produce pictures of the carotid arteries in the neck which carry blood from the heart to the brain. A Doppler ultrasound study – a technique that evaluates blood flow through a blood vessel – is usually part of this exam. It's most frequently used to screen patients for blockage or narrowing of the carotid arteries, a condition called stenosis which may increase the risk of stroke.
What is Carotid Ultrasound Imaging?
Ultrasound imaging, also called ultrasound scanning or sonography, involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the probe through the gel into the body. The transducer collects the sounds that bounce back and a computer then uses those sound waves to create an image. Ultrasound examinations do not use ionizing radiation (as used in x-rays), thus there is no radiation exposure to the patient. Because ultrasound images are captured in real-time, they can show the structure and movement of the body's internal organs, as well as blood flowing through blood vessels.
An ultrasound of the body's two carotid arteries, which are located on each side of the neck and carry blood from the heart to the brain, provides detailed pictures of these blood vessels and information about the blood flowing through them.
A Doppler ultrasound study is usually an integral part of a carotid ultrasound examination.
Doppler ultrasound, also called color Doppler ultrasonography, is a special ultrasound technique that allows the physician to see and evaluate blood flow through arteries and veins in the abdomen, arms, legs, neck and/or brain (in infants and children) or within various body organs such as the liver or kidneys.
Ultrasonography (US) of the carotid arteries is a common imaging study performed for diagnosis of carotid artery disease. In the United States, carotid US may be the only diagnostic imaging modality performed before carotid endarterectomy. Therefore, the information obtained with carotid US must be reliable and reproducible. Technical parameters that can affect the accuracy of carotid US results include the Doppler angle, sample volume box, color Doppler sampling window, color velocity scale, and color gain. Important factors in diagnosis of atherosclerotic disease of the extracranial carotid arteries are the intima-media thickness, plaque morphology, criteria for grading stenosis, limiting factors such as the presence of dissection or cardiac abnormalities, distinction between near occlusion and total occlusion, and the presence of a subclavian steal.
Challenges to the consistency of carotid US results may include lack of a standard protocol, poor Doppler technique, inexperience in interpretation of hemodynamic changes reflected in the Doppler waveform, artifacts, and physical challenges. Hindrances in the classification of problematic carotid artery stenoses may be overcome by following a standard protocol and optimizing scanning techniques and Doppler settings.
Cerebrovascular disease (stroke) is the third leading cause of death in the United States, accounting for approximately 400,000 new cases diagnosed each year and over 163,000 deaths in 2002 (,1). Ultrasonography (US) of the carotid arteries is the modality of choice for triage, diagnosis, and monitoring of cases of atheromatous disease. This is an operator-dependent examination that requires a good understanding of Doppler physics and hemodynamic physiology. The accuracy of carotid US hinges on following standard guidelines and practicing meticulous scanning techniques. There are several pitfalls that may mislead the operator to falsely interpret color and spectral Doppler findings.