Carotid Ultrasound: What It Is, How It Works & When You Need It

What is a carotid ultrasound?

A carotid ultrasound, also known as a carotid duplex, is a non-invasive, painless ultrasound imaging test that uses sound waves to create detailed pictures of the carotid arteries in the neck. These arteries are vital as they supply blood to the brain, neck, and face. 

This test helps your healthcare provider assess how well your blood flows through your two carotid arteries and detect potential blockages affecting the flow of blood. It can also help check if your blood vessels are abnormally narrowed (stenosis) due to plaque buildup, which can increase the risk of stroke.

Why do I need a carotid ultrasound?

Your healthcare provider may perform a carotid ultrasound scan to look for blood clots or plaque (fat and cholesterol deposits) on your carotid artery walls. This is because the plaque can limit or eventually become a blockage to blood flow to your brain, face, and neck.

Doctors may also recommend a carotid ultrasound for other medical conditions, such as: 

• Stroke or transient ischaemic attack (ministroke): To determine if there are any blockages in the blood vessels causing an ischaemic stroke and to prevent potential future stroke risk.

• Symptoms of stroke: If you are experiencing sudden weakness, difficulty speaking, loss of vision, or any other symptoms related to stroke, you may need to take this test.

• High stroke risk: If you  have any stroke risk factors like diabetes, high cholesterol, smoking, or a family history of stroke or heart disease, it may warrant a screening.

• Previous surgery on a narrowed artery: After surgery, a carotid ultrasound helps ensure that the treated artery remains open and that blood flow is restored. It can detect any recurrence of narrowing (restenosis) or other complications at the surgical site.

• Carotid bruit or high blood pressure: If your doctor detects an abnormal sound in the carotid artery, it can indicate a turbulent blood flow within the artery. This condition is commonly caused by atherosclerosis, which is when plaque builds up and makes the artery narrow, turbulent flow resulting from changes in blood viscosity, or other generalised atherosclerosis conditions.

If you have any of the above risk factors that increase the likelihood of blood clots, request an appointment with Thomson Medical. Our specialists can assist with further diagnosis, including a carotid ultrasound to help determine the underlying cause of your symptoms and provide early treatment. 

How does a carotid artery ultrasound work?

A carotid ultrasound uses a handheld device called a transducer to emit sound waves in the neck. These sounds then echo off from the carotid artery and other tissue in the neck back to the transducer. A computer then processes this information from the transducer to make a real-time image that can be displayed, called a sonogram.

There are two common types of carotid ultrasound that healthcare professionals usually perform, which include: 

1. Conventional ultrasound (B-mode): Creates ultrasound images of the artery's structure by using sound waves.

2. Doppler ultrasound: Measures blood flow and detects abnormalities like narrowing or blockages.

What to expect during a carotid ultrasound examination?

Before undergoing the carotid ultrasound test, there are no fasting or special preparations required, unless instructed otherwise by your doctor. However, you might want to wear a comfortable shirt or a loose-fitting one that doesn’t cover your neck.  You may also need to remove any jewellery or accessories worn around your neck.

During the procedure

Throughout the procedure, here are several things you can expect, such as:

• You’ll lie on an examination table with your neck exposed. The ultrasound technician may position your head accordingly to better access the side of your neck.

• The ultrasound technician applies a warm, clear ultrasound gel to your neck to help transmit ultrasound waves.

• The technician will gently press the transducer against the side of your neck and move it around to capture images.

• You may hear pulsing sounds as blood flow if it is measured using Doppler ultrasound.

The test is painless and does not involve radiation; the whole procedure will usually take around 30 minutes. After the procedure, there is no downtime required, and you can go back to your normal activities immediately and head home.

What are the risks of a carotid ultrasound?

Carotid ultrasounds are safe with no known risks. You may feel pressure, but no pain when the transducer pushes on your neck. However, certain conditions like obesity, irregular heart rhythms, or calcium deposits in the arteries may affect image accuracy.

How do I interpret the results of my carotid ultrasound exam?

A doctor who specialises in imaging tests, called a radiologist, will review the results of the carotid ultrasound and may discuss them with you immediately after the procedure. They can also send your test results to your doctor, who will explain the carotid ultrasound results and their implications.

Normal carotid ultrasound results

A normal carotid ultrasound result indicates that the carotid arteries are functioning healthily, and there are no immediate concerns regarding blood flow to the brain due to blockages or narrowing of blood vessels.

Examples of a normal carotid ultrasound result are as follows:

• Smooth blood flow: The blood flow through the carotid arteries should be smooth and laminar, without turbulence.

• No plaque buildup: There should be no evidence of atherosclerotic plaque or intimal thickening visible on the ultrasound images.

• Normal vessel appearance: The carotid arteries should have a smooth echogenic intimal surface and normal vessel walls.

• Peak systolic velocity (PSV): The PSV in the internal carotid artery (ICA) should be less than 125 cm/sec.

• End diastolic velocity (EDV): The EDV in the ICA should be less than 40 cm/sec.

• ICA/CCA PSV ratio: The ratio of the PSV in the internal carotid artery to the common carotid artery should be less than 2.0.

• No significant stenosis: There should be no evidence of narrowing or less than 50% narrowing of the carotid arteries.

• Normal waveforms: The ultrasound should show normal waveforms with antegrade flow (towards the brain) and low resistance, similar to the ICA.

What are abnormal carotid ultrasound results?

If you get an abnormal carotid ultrasound, it means there are problems with the carotid arteries. These problems can affect blood flow to the brain, raise the risk of stroke, and usually need more testing or treatment, like changes to your lifestyle, medication, or surgery. 

Examples of abnormal carotid ultrasound results are as follows:

• Narrowing of blood vessels or stenosis: Presence of arterial narrowing, classified as mild (<50%), moderate (50-69%), severe (≥70%), or total occlusion (100%).

• Plaque buildup: Visible atherosclerotic plaques within the arterial walls, which may be stable or unstable.

• Turbulent blood flow: Abnormal Doppler waveforms indicating disrupted or irregular blood flow patterns.

• Elevated velocity measurements: PSV in the ICA exceeding 125 cm/sec, indicating potential stenosis.

• Abnormal ICA/CCA PSV ratio: A ratio greater than 2.0 suggests significant stenosis.

• Intima-media thickness (IMT): Increased thickness of the inner layers of the artery wall, indicating early stages of atherosclerosis.

• Vessel wall irregularities: Abnormal appearance of the arterial walls, such as ulcerations or dissections.

• Retrograde flow: Blood flowing in the opposite direction, potentially indicating severe blockages elsewhere.

Your doctor will explain these findings and recommend further tests or treatments if necessary.

If your carotid ultrasound shows abnormal conditions, don't hesitate to consult a doctor. Request an appointment with Thomson Medical for recommendations based on your medical conditions and further evaluation.

Available treatments for an abnormal carotid test result

There are different treatment options available for you depending on the severity of your blockage:

1. Lifestyle changes: Healthy diet, exercise, maintaining a healthy weight, and stopping smoking habits are some lifestyle changes you can take.

2. Medications: Taking medicines to lower blood cholesterol, blood pressure and other medicines to prevent blood clots, antiplatelet agents, or anticoagulants.

3. Surgical procedures:

   • Carotid endarterectomy: removal of carotid artery plaques.

   • Carotid angioplasty and stenting: implantation of a wire mesh (stent) to widen your carotid artery to restore and improve blood flow.

Should you require a more comprehensive treatment, your doctor will discuss with you the possible options available based on your own unique situation.

Overall, a carotid ultrasound test is an essential diagnostic tool for assessing stroke risk and vascular health. It’s safe, painless, and provides critical information for preventing life-threatening conditions like strokes.

FAQ

What causes an ischaemic stroke?

An ischaemic stroke occurs when a blood clot, known as a thrombus, blocks or plugs an artery leading to the brain. A blood clot often forms in arteries damaged by a buildup of plaques, known as atherosclerosis.

What will a carotid ultrasound show?

It shows blood flow patterns in your carotid arteries and detects blockages, narrowing, or plaque buildup that could increase stroke risk.

What are the warning signs of a blocked carotid artery?

Symptoms include sudden weakness, numbness on one side of the body, difficulty speaking, vision changes, or dizziness, common signs of stroke or ministroke.

What not to do before a carotid ultrasound?

Avoid wearing necklaces or high-collared clothing that could obstruct access to your neck during the procedure.

At what age should you get a carotid ultrasound?

There’s no universal age recommendation; however, individuals over 50 with risk factors like hypertension or diabetes may benefit from screening.

How much carotid artery blockage is normal?

If the narrowing is less than 50%, it is considered mild and may not require immediate intervention, but regular monitoring is necessary.

How can I naturally clear my carotid artery?

While complete reversal isn’t possible naturally, you can slow progression by adopting a healthy lifestyle: eating heart-friendly foods, exercising regularly, managing stress, and avoiding smoking.

The information provided is intended for general guidance only and should not be considered medical advice. For personalised recommendations and tailored advice, request an appointment with Thomson Medical.