This test uses an ultrasound machine, which includes a computer, a screen, and a transducer. The transducer is a portable device that sends and receives sound waves. In conjunction with Doppler ultrasound, this test can also show how blood is moving through your blood vessels. Carotid ultrasound is done to detect the build-up of plaque in one or both carotid arteries on the neck and to see if the build-up is narrowing your carotid arteries and blocking blood flow to the brain. Test results help your doctor plan treatment to remove plaque and prevent stroke.

Carotid ultrasound is usually done in a doctor's office or hospital. For your test you lie on your back on an exam table. The ultrasound technician will apply gel to your neck where your carotid arteries are located. The gel helps the sound waves reach your arteries. The technician will move the transducer against different parts of your neck. The transducer detects the sound waves after they bounce off your artery walls and blood cells. A computer uses the sound waves to create and record images of the inside of your carotid arteries and to show how the blood flows in your carotid arteries.

Carotid ultrasound has no risks because the test uses harmless sound waves. They are the same kind of sound waves that doctors use to take and record pictures of a baby inside a pregnant woman.