Ultrasound imaging is similar to sonar used by boats and utilizes the same kind of sound waves to produce pictures of fetuses in pregnant women. These harmless, high-frequency sound waves also are used to capture real-time views of blood flowing through blood vessels, such as carotid arteries.
Carotid arteries are located on each side of the neck and supply blood to the brain. People with carotid artery disease have a narrowing, or stenosis, of these arteries caused by a build up of plaque, which is made of fat, cholesterol, calcium and other substances.
A stroke may occur if a blood clot becomes lodged in the narrowed artery. There are no symptoms of this disease, but doctors can perform a carotid ultrasound test to diagnose it.
During the test, the patient lies face up on an exam table with the head supported to prevent movement. A water-soluble gel is placed on the neck area where the carotid arteries are located. A transducer, which emits inaudible sound waves, is then moved gently back and forth over the arteries.
A computer records measurements and creates real-time pictures that can help identify any narrowing, clotting or other blockage in the carotid arteries. Test results are interpreted by a radiologist, a doctor specially trained to supervise and analyze radiology examinations.
A carotid ultrasound test is a painless, non-invasive procedure that is performed in a doctor’s office or the peripheral vascular lab of a hospital.
No preparation is necessary, and the test is typically completed in about 30 minutes. The patient can resume normal activities immediately after the procedure.
The test may be recommended if an abnormal sound in the carotid artery, called a bruit, is detected using a stethoscope. A doctor may order a carotid ultrasound to determine if blood flow is slow or weakened due to blood clots or a split in the layers of the artery wall.
A carotid ultrasound also may be performed as a screening test for people with high blood pressure or diabetes who are at increased risk for having a stroke. Patients who have undergone carotid artery surgery may need a follow-up ultrasound to make sure blood flow has been restored.
Likewise, a carotid ultrasound may be necessary to check that a stent (small mesh tube) has been surgically placed properly to help prevent further narrowing of the artery.
Ultrasound testing has numerous benefits. It is widely available and uses harmless sound waves to create clear pictures of soft tissues that are not readily visible on X-rays.
Ultrasound is a painless, non-invasive procedure that requires no injections or needles, and it can be repeated as often as is medically necessary. However, the test may not detect small amounts of soft plaque, and some patients may not be candidates for the test due to the shape or size of their necks.