Carotid Ultrasound (Carotid Doppler)

Definition:
Ultrasound uses sound waves instead of radiation to generate snapshots or moving pictures of structures inside the body. This imaging technique works in a manner similar to radar and sonar, developed in World War II to detect airplanes, missiles, and submarines that were otherwise invisible. After coating your skin with a lubricant to reduce friction, a radiologist or ultrasound technician places an ultrasound transducer, which looks like a microphone, on your skin and may rub it back and forth to get the right view. The transducer sends sound waves into your body and picks up the echoes of the sound waves as they bounce off internal organs and tissue. A computer transforms these echoes into an image that is displayed on a monitor…….....CLICK & SEE

Doppler ultrasound is a variation of this technique that not only shows internal structures but also examines the flow of blood through blood vessels. Using the Doppler effect—the change in the frequency of sound or light waves as they bounce off a moving object—this kind of ultrasound produces an image of blood in motion…..CLICK & SEE

A Carotid ultrasound shows the amount of blood flow in the carotid arteries, the major blood vessels to the brain located on either side of your neck. With this imaging technique, your doctor can see if there is any narrowing of your carotid arteries because of cholesterol deposits or some other problem. This test is often used to evaluate people who have had a stroke or who might be at high risk for one because of reduced blood flow in the carotid arteries…......CLICK & SEE.

Who Needs Carotid Ultrasound?
Carotid ultrasound checks for plaque buildup in the carotid arteries. This buildup can narrow or block your carotid arteries. You may need a carotid ultrasound if you:

*Had a stroke or ministroke recently.
*Have an abnormal sound in your carotid artery called a carotid bruit (broo-E).

Your doctor can hear a carotid bruit with the help of a stethoscope put on your neck over the carotid artery. A bruit can mean that there’s a partial blockage in your carotid artery that could lead to a stroke.
Your doctor also may order a carotid ultrasound if he or she suspects you may have:

*Blood clots that can slow blood flow in your carotid artery
*A split between the layers of your carotid artery wall that weakens the wall or reduces the blood flow to your brain
A carotid ultrasound also may be done to see whether carotid artery surgery has restored normal blood flow. If you had a procedure called carotid stenting, your doctor may order a carotid ultrasound afterward to check the position of the stent put in your carotid artery. (The stent, a small mesh tube, helps prevent the artery from becoming narrowed or blocked again.)

Sometimes carotid ultrasound is used as a preventive screening test in people who have medical conditions that increase their risk of stroke, including high blood pressure and diabetes. People with these conditions may benefit from having their carotid arteries checked regularly even if they show no signs of plaque buildup.

What To Expect Before Carotid Ultrasound
Carotid ultrasound is a painless test, and typically there is little to do in advance. Your doctor will tell you how to prepare for your carotid ultrasound.

Process of Performing the Test.:
After squirting some clear jelly onto one side of your neck to help the ultrasound sensor slide around easily, a technician places the sensor against your skin. An image then appears on a video screen . As the technician moves the sensor back and forth on your neck, different views of the carotid artery appear on the screen. As the equipment measures the blood flow through the artery, you hear a noise that sounds like your heartbeat. The other side of your neck is checked in the same way. This test usually takes 15–30 minutes.

The ultrasound machine includes a computer, a video screen, and a transducer, which is a hand-held device that sends and receives ultrasound waves into and from the body.

You will lie down on your back on an exam table for the test. Your technician or doctor will put a gel on your neck where your carotid arteries are located. This gel helps the ultrasound waves reach the arteries better. Your technician or doctor will put the transducer against different spots on your neck and move it back and forth.

FIG-A

 

 

 

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……….Fig->A.
The above Figure shows how the ultrasound probe is placed over the carotid artery. Figure B is a color ultrasound image showing blood flow (the red color in the image) in the carotid artery. Figure C is a waveform image showing the sound of flowing blood in the carotid artery.

The transducer gives off ultrasound waves and detects their echoes after they bounce off the artery walls and blood cells. Ultrasound waves can’t be heard by the human ear.

A computer uses the echoes of the ultrasound waves bouncing off the carotid arteries to create and record images of the insides of the arteries (usually in black and white) and your blood flowing through them (usually in color; this is the Doppler ultrasound). A video screen displays these live images for your doctor to review.

Risk Factor:
There are no risks linked to having a carotid ultrasound, because the test uses harmless sound waves. These are the same type of sound waves that doctors use to record pictures of fetuses in pregnant women.

What one must do after the test is over?
Carotid ultrasound is usually done in a doctor’s office or hospital. The test is painless and usually doesn’t take more than 30 minutes.
Usually there is nothing special you have to do after a carotid ultrasound, and you should be able to return to normal activities immediately.

Often your doctor will be able to tell you the results of the carotid ultrasound when it occurs or soon afterward.

What Does a Carotid Ultrasound Show?
A carotid ultrasound can show whether buildup of a fatty material called plaque has narrowed one or both of your carotid arteries and reduced blood flow to your brain.

.Fig->B………………….
The illustration shows a normal artery with normal blood flow (figure A) and an artery containing plaque buildup ( figure B).

If your carotid arteries are narrowed by plaque, you may be at risk for having a stroke. That risk depends on how much of your artery is blocked and how much blood flow is restricted. To reduce your risk for stroke, your doctor may recommend medical or surgical treatments to reduce or remove the plaque buildup in your carotid arteries.

How long is it before the result of the test is known?
The technician records the test on videotape for review by a radiologist. The radiologist then makes measurements from the video picture and submits a report to your doctor. Your doctor should have the results within a few days.

Key Points to Note:
*Carotid ultrasound is a test that uses high-frequency sound waves to create images of the insides of the two large arteries in your neck. These arteries, called carotid arteries, supply your brain with blood.

*A carotid ultrasound can show whether buildup of a fatty material called plaque has narrowed one or both of your carotid arteries and reduced blood flow to your brain.

*If your carotid arteries are narrowed by plaque, you may be at risk for having a stroke, depending on how much of your artery is blocked and how much blood flow is restricted.

*You may need a carotid ultrasound if you had a stroke or ministroke recently or are at high risk for having a stroke.

*Carotid ultrasound is a painless test done in a doctor’s office or hospital. It usually doesn’t take more than 30 minutes and requires no preparation or followup.

*There are no risks linked to having a carotid ultrasound, because the test uses harmless sound waves.

Resources:
http://www.health.harvard.edu/diagnostic-tests/carotid-ultrasound.htm
http://www.nhlbi.nih.gov/health/dci/Diseases/cu/cu_all.html

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