A carotid ultrasound is a non-invasive and risk-free diagnostic imaging procedure that provides a detailed picture of your carotid arteries. These two major arteries, located on each side of your neck, are the main conduits for blood flow to the brain. The primary purpose of a carotid ultrasound is to screen for and diagnose carotid artery disease, a condition where these arteries become narrowed due to a buildup of fatty deposits called plaque. This narrowing, known as stenosis, is a major risk factor for ischemic stroke.

The ultrasound uses high-frequency sound waves to create images of the artery's structure, allowing your doctor to see the plaque buildup, and it employs a special technique called Doppler to measure the speed and direction of blood flow through the vessel. This combination of structural and functional information makes the carotid ultrasound an incredibly powerful tool for assessing your risk of a future stroke. It can detect blockages long before they become critical and is the essential first step in the investigation of patients who have experienced a Transient Ischemic Attack TIA or a minor stroke.

The procedure is entirely painless, involves no radiation, and provides immediate, real-time information to your physician. At Fortis Healthcare, our advanced radiology and vascular labs are equipped with state-of-the-art ultrasound technology, operated by highly skilled sonographers and interpreted by expert radiologists and vascular specialists to provide you with the clearest possible picture of your cerebrovascular health.

The Science: How Carotid Ultrasound Works

A carotid ultrasound is a sophisticated procedure that combines two different types of ultrasound technology to provide a comprehensive assessment of the artery.

B-Mode Imaging: Visualizing the Structure

The first part of the test uses standard ultrasound technology, also known as B-mode imaging.

• The Principle: A small, handheld device called a transducer is placed on your neck with a clear, water-based gel. The transducer emits high-frequency sound waves that are inaudible to the human ear. These sound waves travel into the neck and bounce off the different tissues, including the walls of the carotid artery and any plaque that is present.
   
• Creating the Image: The transducer then detects these returning echoes. The ultrasound machine's computer analyzes the time and intensity of the echoes to generate a real-time, two-dimensional, black-and-white image of the artery. This allows the radiologist to directly visualize the structure of the artery wall and to see and measure the thickness and characteristics of any atherosclerotic plaque.

Doppler Ultrasound: Measuring Blood Flow

The second, and equally important, part of the test uses a specialized technique called Doppler ultrasound.

• The Doppler Effect: This technique is based on a principle of physics called the Doppler effect, which describes the change in frequency of a wave in relation to an observer moving relative to the wave source. A common example is the change in pitch of an ambulance siren: as it approaches you, the pitch is high, and as it moves away, the pitch drops.
• Application in Ultrasound: The Doppler ultrasound sends sound waves into the artery that bounce off the moving red blood cells. The machine measures the change in frequency of the returning echoes. This change allows it to calculate with incredible precision both the direction and the velocity or speed of the blood flow.
• Color Doppler: The machine often color-codes this information and overlays it on the black-and-white B-mode image. By convention, blood flowing towards the transducer may be colored red, and blood flowing away may be colored blue. This creates an intuitive visual map of the blood circulation.
• Spectral Doppler: The most critical part of the assessment involves Spectral Doppler. The technologist places a specific cursor within the artery on the screen and the machine generates a graph, or waveform, that plots the velocity of blood flow over time. A key measurement is the Peak Systolic Velocity PSV. In a narrowed segment of the artery, blood must speed up to get through, just like water in a pinched hose. By measuring how high the velocity is, the radiologist can accurately calculate the percentage of stenosis or blockage in the artery.

Understanding the Underlying Condition: Carotid Artery Disease

The carotid ultrasound is the primary tool for diagnosing carotid artery disease, which is a localized form of a systemic condition called atherosclerosis.

Atherosclerosis and Plaque Formation

Atherosclerosis is the hardening and narrowing of the arteries caused by the gradual buildup of plaque. Plaque is a complex substance made up of cholesterol, fats, calcium, and cellular debris. This process can happen in any artery in the body, and when it occurs in the carotid arteries, it poses a direct threat to the brain. The plaque can be stable and calcified or soft and ulcerated. Soft, irregular plaque is considered more dangerous as it is more likely to rupture and break away.

The Link to Stroke and TIA

A narrowed carotid artery can cause an ischemic stroke which is a stroke caused by a blockage in two main ways:

• Embolism: A small piece of the plaque or a blood clot that has formed on the plaque's surface can break free. This debris, called an embolus, travels through the bloodstream up into the smaller arteries of the brain until it becomes lodged, cutting off blood supply to a part of the brain tissue. This is the most common cause of stroke from carotid disease.
• Thrombosis: The plaque can grow so large that it severely restricts blood flow, or a clot can form directly on the plaque, completely blocking the artery.

A Transient Ischemic Attack TIA or "mini-stroke" is a critical warning sign. It produces stroke-like symptoms that are temporary because the blockage resolves on its own. The symptoms of a TIA or stroke can be remembered with the acronym F.A.S.T.:

• Face Drooping
• Arm Weakness
• Speech Difficulty
• Time to call emergency services

When is a Carotid Ultrasound Recommended?

Your doctor may recommend a carotid ultrasound for several reasons:

After a TIA or Stroke: It is a standard and essential part of the workup to determine if a blockage in the carotid artery was the cause.

Presence of a Carotid Bruit: A bruit is an abnormal "whooshing" sound that a doctor might hear with a stethoscope placed over your neck. This sound is caused by turbulent blood flow through a narrowed artery and is a strong indication for an ultrasound.

Screening for High-Risk Individuals: For patients who have not had symptoms but have multiple, significant risk factors for stroke and atherosclerosis, such as:

• Known Coronary Artery Disease or Peripheral Artery Disease.
• A long history of smoking.
• Poorly controlled high blood pressure.
• High cholesterol.
• Diabetes.

Follow-up After a Procedure: To monitor the carotid artery after a surgical procedure like a carotid endarterectomy or a carotid artery stent to ensure it has remained open.

Monitoring of Known Stenosis: For patients with a known moderate blockage, periodic ultrasounds are used to track whether the plaque is progressing.

Our Specialists

A carotid ultrasound is performed by a trained vascular sonographer, and the results are interpreted by a specialist physician, such as a radiologist, vascular surgeon, or neurologist, who will use the information to guide your treatment plan.

Dr. Vivek Kumar

ADDITIONAL DIRECTOR NON INVASIVE CARDIOLOGY | Fortis Okhla

Dr. Ravindra Singh

CONSULTANT ORTHOPAEDICS | Fortis Okhla

Dr. Mousam Dey

CONSULTANT INTERVENTIONAL RADIOLOGY | Fortis Anandapur

Patient Stories

"During a routine check-up, my family doctor heard a strange sound in my neck and sent me for a carotid ultrasound. I had no symptoms and felt perfectly fine, so I was quite surprised. The test itself was so simple and completely painless. The result, however, showed a 75% blockage in my left carotid artery. The doctor explained that I was a ticking time bomb for a stroke. That simple, non-invasive ultrasound was the first step that led to a successful stenting procedure and has undoubtedly saved me from a major health crisis." - Praveen Kumar, 68, Gurugram

"I had a scary episode where I lost vision in my right eye for about five minutes and my speech became slurred. It was diagnosed as a TIA. In the hospital, one of the first tests I had was a carotid ultrasound. The radiologist was able to show me the image on the screen, a large plaque that was narrowing the artery. Seeing that clear picture helped me understand what had happened. It provided the definitive diagnosis that allowed my neurology team to act quickly and plan the right treatment to prevent a permanent stroke." - Shreya Sharma, 62, Delhi

The Carotid Ultrasound Procedure: A Detailed Walkthrough

Preparation

There is very little preparation required for a carotid ultrasound.

• You can eat and drink normally on the day of the test.
• Wear a comfortable shirt with an open collar and remove any necklaces or dangling earrings.

What Happens During the Test

The procedure is performed in the radiology department or a vascular lab and typically takes about 30 to 45 minutes.

• Positioning: You will be asked to lie on your back on an examination table. A pillow may be placed under your head to provide support and to slightly extend or turn your neck for better access.
• Gel Application: The sonographer will apply a warm, water-based gel to the skin on the side of your neck. This gel helps to eliminate any air pockets between the transducer and your skin, allowing for the best possible transmission of the sound waves.
• The Scan: The sonographer will press the transducer firmly against your skin and move it back and forth over the area of your carotid artery. You should not feel any pain, only light pressure from the transducer.
• Doppler Sounds: During the Doppler portion of the exam, you may hear a "whooshing" sound, which is the sound of your blood flowing through the artery.
• Remaining Still: The sonographer may ask you to hold your breath for a few seconds at a time or to change the position of your head slightly. It is important to remain still and not to talk during the measurement process to ensure the highest quality images.
• Both Sides Examined: The entire process is repeated for the carotid artery on the other side of your neck.
• Completion: Once all the images and measurements have been taken, the gel is wiped off your neck, and you are free to leave and resume all normal activities immediately.

Myths vs Facts

Take the Next Step

Your carotid arteries are the lifelines to your brain. Protecting them is a critical part of preventing a stroke. A carotid ultrasound is a simple, safe, and powerful tool that provides an essential look at the health of these vital vessels. It can offer the peace of mind that comes with a normal result or provide the crucial early detection of a problem, allowing you and your doctor to take proactive steps to safeguard your future.

If you have experienced symptoms of a TIA or have multiple risk factors for stroke, such as a history of smoking, diabetes, or high blood pressure, do not delay in seeking medical advice. A consultation with your doctor to discuss whether a carotid ultrasound is right for you is a simple and important step in taking control of your cardiovascular health.

CTA: Book a Health Check / Consult a Neurologist or Cardiologist

Frequently Asked Questions

Q1. How long does a carotid ultrasound take to perform?

Ans. The entire procedure typically takes about 30 to 45 minutes to ensure that the sonographer can obtain all the necessary images and detailed blood flow measurements from both sides of your neck.

Q2. When will I get the results?

Ans. A specialist radiologist or vascular doctor needs to carefully review all the images and Doppler data to create a formal report. This report is usually sent to your referring physician within one to two business days, who will then discuss the results with you.

QG3. What does it mean if the report mentions plaque?

Ans. The presence of plaque indicates that you have some degree of atherosclerosis. The report will describe the plaque's location, its thickness, and its characteristics such as whether it is soft or hard and calcified. This information helps your doctor to assess your overall cardiovascular risk and to recommend appropriate lifestyle changes and medications like statins.

Q4. How is the percentage of stenosis or blockage calculated?

Ans. The percentage of stenosis is not just a visual estimate. It is calculated using a set of established criteria that correlate the peak velocity of the blood flow measured by the Doppler with the degree of narrowing in the artery. A very high velocity indicates a very tight narrowing.

Q5. Is there anything I need to do to prepare for the test?

Ans. No specific preparation is needed. You can eat, drink, and take your medications as usual on the day of the test. It is helpful to wear a comfortable shirt with an open neck or one that is easy to remove.

Q6. What happens if my carotid ultrasound is abnormal?

Ans. If your ultrasound shows a mild or moderate blockage, your doctor will likely recommend aggressive medical management, which includes lifestyle changes and medications to control your risk factors. If the test shows a severe blockage, your doctor will refer you to a specialist to discuss further treatment options, which could include open surgery, carotid endarterectomy or a minimally invasive carotid artery stent.

QG7. How often should I have this test done?

Ans. If your initial test is normal, you will not need it repeated unless you develop new symptoms. If you have a known moderate stenosis, your doctor may recommend a follow-up scan every 6 to 12 months to monitor for any progression of the plaque buildup.

Q8. Is a carotid ultrasound reliable?

Ans. Yes, when performed by a skilled and experienced sonographer and interpreted by an expert radiologist, a carotid duplex ultrasound is a highly accurate and reliable test for detecting and quantifying the severity of carotid artery stenosis.