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PubMed This is a summary of 24 peer-reviewed journal articles Updated
Vascular Surgery · Carotid Artery Stenosis

Diagnostic Testing & Understanding Your Results

At a Glance

Carotid stenosis results depend on both the scan and how narrowing is measured. Ultrasound provides blood-flow speeds, while CT or MR angiography may confirm the finding, especially when calcium limits ultrasound. Doctors use standard percentages and plaque features to guide treatment decisions.

Navigating your diagnostic reports can feel like learning a new language. Your medical team uses several different tests to create a complete picture of your carotid arteries, as no single test is perfect [1][2]. Understanding the specific terms and measurement methods used in these reports is essential for making informed decisions about your care.

The Diagnostic Sequence

For most patients, the journey begins with a Carotid Duplex Ultrasound (DUS). This is a non-invasive test that uses sound waves to “see” the plaque (B-mode) and measure the speed of blood flow (Doppler) [3].

While ultrasound is an excellent screening tool, it has a significant limitation: acoustic shadowing [4]. If your plaque is heavily calcified (hardened with calcium), the sound waves cannot penetrate it, creating a “shadow” that hides the artery’s interior [5]. Because of this, or when surgery is being considered, doctors often order a confirmatory scan—usually a CT Angiography (CTA) or MR Angiography (MRA)—before making a final treatment decision [1][6].

Understanding the Measurement Methods

The percentage of narrowing (e.g., “70% stenosis”) depends entirely on how it was measured.

  • The NASCET Method: This is the standard angiographic diameter method used in major clinical trials [7]. It compares the narrowest part of the artery to the healthy, normal-sized artery further up toward the brain [8]. While an ultrasound report might not explicitly use the word “NASCET,” validated velocity criteria are designed to approximate this standard. If it isn’t there, your doctor may need to re-calculate the percentage or use other methods to ensure you are being compared to the correct treatment guidelines [9][10].
  • The Area Method: Some CTA reports calculate narrowing based on the cross-sectional area rather than the diameter. Area-based measurements often overestimate the severity compared to NASCET measurements [7][11].

Key Terms on Your Report

Velocity Measures (Ultrasound)

  • Peak Systolic Velocity (PSV): The highest speed of blood as the heart contracts. In a narrowed artery, blood must speed up to get through the tight spot [3]. A PSV over 230 cm/s can often suggest a narrowing of 70% or more, depending on the lab’s criteria [12][13].
  • End-Diastolic Velocity (EDV): The speed of blood when the heart is resting between beats. High EDV numbers (above 100 cm/s) are another indicator of severe narrowing [12][14].

Plaque Appearance (Vulnerability)

  • Echolucent / Hypoechoic: This means the plaque looks dark on the ultrasound. It is a nonspecific marker that can suggest “soft” plaque rich in fat or containing intraplaque hemorrhage (bleeding inside the plaque) [15][16]. While it does not perfectly predict an imminent event, it is one factor doctors use to assess plaque risk alongside other clinical details [17][18].
  • Ulceration: This means the surface of the plaque is jagged or has a crater, which can trap blood and form clots [19][20].

Occlusion States

  • Near-occlusion: This is severe stenosis with marked reduction in the size of the artery beyond the blockage [21][22]. It requires specialized treatment decisions because the risks and benefits of surgery differ from standard severe stenosis [23].
  • Complete Occlusion: The artery is 100% blocked and no blood is flowing through that segment [1]. Standard surgery (like CEA) is generally not performed for a completely blocked artery. However, this is not a benign state; fragments can still cause issues, and hemodynamic or collateral vascular risks remain. Specialist evaluation is always required [24].

Your Report Completeness Checklist

Check your diagnostic report for these pieces of information. If they are missing or unclear, ask your doctor for clarification:

  1. Measurement Method: Does the CTA report state how the stenosis was measured?
  2. Velocity Data: Are the PSV and EDV numbers listed on the ultrasound?
  3. Plaque Description: Does the report describe the plaque as calcified, echolucent, or ulcerated?
  4. Comparison: If you’ve had previous scans, does this report state if the narrowing has progressed?

Common questions in this guide

Which tests are used to check for carotid stenosis?
A carotid duplex ultrasound is commonly the first test because it shows plaque and measures blood-flow speed without radiation. If calcium blocks the ultrasound view or a procedure is being considered, CT angiography or MR angiography may be used to confirm the finding. No single test is perfect, so clinicians may compare results.
Why does the measurement method matter on a carotid stenosis report?
The percentage of narrowing can change depending on how it is calculated. NASCET compares the narrowest part of the artery with a normal segment farther toward the brain, while area-based measurements can report a higher percentage. Ask which method was used before comparing a result with treatment guidelines.
What do PSV and EDV mean on a carotid ultrasound?
PSV is the highest blood-flow speed when the heart contracts, and EDV is the speed between beats. Higher values can signal more severe narrowing; a PSV above 230 cm/s and EDV above 100 cm/s may support severe stenosis under commonly used criteria. Your laboratory's standards and other imaging findings also matter.
What do echolucent or ulcerated plaque findings mean?
Echolucent or hypoechoic plaque looks dark on ultrasound and may reflect softer, fatty plaque or bleeding within the plaque. Ulceration means the plaque surface has a crater or irregular break that can promote clot formation. These features help assess risk but do not by themselves predict what will happen or determine treatment.
What is the difference between near-occlusion and complete carotid occlusion?
Near-occlusion is severe narrowing with a marked reduction in the size of the artery beyond the blockage, while complete occlusion means the artery is fully blocked through that segment. The two findings can require different management decisions. Standard carotid endarterectomy is generally not performed for a completely blocked artery, but specialist evaluation is still needed.
Can heavy calcium make a carotid ultrasound less accurate?
Yes. Heavy calcification can block sound waves and create acoustic shadowing, which hides part of the artery. A clinician may use CT angiography or MR angiography when the ultrasound view is limited or before deciding on surgery.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Was my stenosis measured using the NASCET criteria or an equivalent standard?
  2. 2.Did heavy calcification or 'acoustic shadowing' interfere with the accuracy of my ultrasound results?
  3. 3.My report mentions 'echolucent' plaque; how does this influence your recommendation for medical therapy versus surgery?
  4. 4.How do my ultrasound velocity numbers (PSV and EDV) compare to the findings on my CT or MR scan?
  5. 5.The report mentions 'near-occlusion'—does this change the type of procedure you are recommending?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (24)
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    Why are we still debating criteria for carotid artery stenosis?

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This page is for informational purposes only and does not constitute medical advice. Ask your treating clinician or a vascular specialist to interpret your carotid stenosis results and recommend care for your situation.

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