A CIMT report usually tells you three things: how thick the wall of your carotid artery is, how that compares with other people your age and sex, and whether any plaque was seen. Of the three, the plaque finding carries the most weight.
It helps to know the limits before you read the numbers. Wall thickness adds only a little to predicting heart attacks and strokes, and US guidance does not recommend CIMT as a routine test for that purpose. Your report is one piece of evidence, not a verdict.
Key takeaways
- Thickness is measured in fractions of a millimeter, so tiny differences are easy to over-read.
- Your percentile or "vascular age" depends on which reference group the software compares you with.
- Plaque, if present, tells you more than thickness does.
- Adding thickness to a standard risk score changed the risk category for very few people in a large pooled study.
- Changes between two scans have not been shown to predict events, so small shifts deserve caution.
The three parts of a report
| Line on the report | What it means | How much weight to give it |
|---|---|---|
| Thickness in millimeters | Combined depth of the two inner wall layers | Modest |
| Percentile or vascular age | Your thickness compared with a reference group | Modest, and depends on the reference used |
| Plaque present or absent | A localized build-up bulging into the artery | The most informative line |
For how the scan is done and who it may suit, see our guide to the CIMT ultrasound. This page is about reading the result.
The thickness number
The scan measures the intima and the media, the two innermost layers of the artery wall, usually in the common carotid artery on each side of the neck. The result is a small number, a fraction of a millimeter.
Thicker walls go with older age, higher blood pressure and other risk factors. A thicker-than-expected wall suggests your arteries have had more wear than usual for your age. It is not the same as having plaque, and it is not a measure of narrowing.
Because the numbers are so small, a slight difference can come from the angle of the probe or the exact spot measured. Read the result as a general signal, not to the last decimal place.
Percentile and vascular age
Most reports turn the raw thickness into something easier to grasp. A percentile ranks you against people of your age and sex. A "vascular age" flips that around and gives the age at which your thickness would be average.
Both depend entirely on the reference group built into the software, and reference groups do not agree. When researchers pooled 22 population cohorts from Europe, North America and Asia, they found the spread of CIMT values too wide to define universal or even regional reference values.1
In practice that means a percentile is a rough ranking. The same artery could land on a different percentile with different software. Avoid comparing a result from one clinic with a result from another.
Plaque: the line that matters most
Plaque is different from general thickening. One international consensus defines carotid plaque as a focal structure that pushes into the artery by at least 0.5 mm or 50% of the surrounding wall thickness, or that measures more than 1.5 mm thick.2
Finding plaque means atherosclerosis has started, at least in that artery. It is also the better predictor. In a pooled analysis of 11 population studies with 54,336 people, carotid plaque predicted future heart attacks more accurately than wall thickness did.3
Keep that in proportion too. In the same analysis neither measure was a strong predictor by itself. Plaque on a CIMT scan is a reason to take your risk factors seriously. It does not show narrowing or blood flow. Those are assessed with a different scan, described in CIMT vs. carotid Doppler.
How far the result should move you
This is where candor matters. The 2013 ACC/AHA risk assessment guideline recommended against measuring CIMT in routine clinical practice to assess the risk of a first cardiovascular event.4
The main evidence behind that position was a pooled analysis of 14 population cohorts and 45,828 people. Adding common carotid thickness to a standard risk score changed the net risk classification by only 0.8% overall and by 3.6% among people at intermediate risk, an improvement the authors judged unlikely to be of clinical importance.5
So a normal thickness does not clear you, and a raised thickness does not condemn you. The result is most useful when it is combined with your labs, your history and, where relevant, a coronary calcium score, which looks at the heart arteries directly.
Reading a repeat scan
People often want to track CIMT over time. Be careful with small changes.
In a pooled analysis of 16 studies and 36,984 people, the change in thickness between two scans was not associated with later heart attacks, strokes or vascular deaths, while the average thickness across the scans was.6
The same project found that, in people scanned four times, the rate of change measured in one interval did not match the rate in the next. That points to measurement noise being as large as the true change. One international consensus group recommends against serial monitoring in individual patients.2
Our clinic may repeat CIMT for members, depending on the first result and your risk profile. If you have a repeat scan, ask how large a change would need to be before it counts as real, and give more weight to new plaque than to a small shift in thickness.
CIMT in the Cardio Res-Q Enhanced Assessment
CIMT is part of the Enhanced Assessment ($999), which also includes a coronary calcium score and everything in the Comprehensive Assessment ($775): Dr. Varano's clinical evaluation, the advanced lab panel and the Quest cardiac panel. Your provider reviews the imaging together with your labs, not as a stand-alone result.
If you are deciding whether the imaging is worth adding, read Comprehensive vs. Enhanced: which to choose. You can book from the Cardio Res-Q program page.
Are You a Candidate for Cardio Res-Q?
Three quick questions about the risk factors we screen for. Your answers stay between you and the clinic.
Frequently asked questions
What is a normal CIMT measurement?
There is no single normal value. Thickness rises with age and differs by sex, and published reference ranges vary too much to give one universal number. Your report's percentile is the practical guide, read with the caveats above.
My report says my vascular age is ten years older than I am. How worried should I be?
Treat it as a prompt, not a diagnosis. It means your wall thickness is above average for your age in that software's reference group. Whether it matters depends on whether plaque was seen and on the rest of your risk factors.
No plaque was found. Does that mean my arteries are clear?
It means none was seen in the segments of the neck arteries that were scanned. It says nothing directly about the arteries of the heart, and early plaque can be missed. It is a favorable finding, not an all-clear.
Can my CIMT number improve?
Small changes up or down are often within measurement error, and research has not shown that tracking the change predicts outcomes for an individual. Controlling blood pressure, cholesterol and blood sugar is worthwhile whatever the next scan shows.
Related reading
This article is for general education and is not medical advice. Decisions about testing and medication should be made with your clinician. If you have chest pain or other symptoms of a heart attack, call 911.
