The Key Measurements in Every Carotid Report
A standard carotid duplex ultrasound evaluates both the right and left carotid arteries and typically reports findings on three segments of each: the common carotid artery (CCA), the internal carotid artery (ICA), and the external carotid artery (ECA). The internal carotid is the most clinically important because it supplies blood directly to the brain.
The primary measurements are peak systolic velocity (PSV) and end diastolic velocity (EDV), both measured in centimeters per second. PSV is the speed of blood flow at the moment the heart contracts; EDV is the speed between beats. The ratio of the ICA PSV to the CCA PSV is also reported and is used to estimate the degree of stenosis (narrowing).
What the Velocity Numbers Mean
Normal ICA peak systolic velocity is typically below 125 cm/s. As the artery narrows due to plaque buildup, blood is forced through a smaller opening — like water through a pinched hose — and velocity increases. Elevated velocities indicate stenosis.
An ICA PSV of 125–230 cm/s with an ICA/CCA ratio of 2.0–4.0 suggests 50–69% stenosis — moderate narrowing that warrants close monitoring and aggressive medical management. An ICA PSV above 230 cm/s with an ICA/CCA ratio above 4.0 suggests 70% or greater stenosis — severe narrowing that typically warrants a vascular surgery consultation. These thresholds are guidelines; your cardiologist will interpret them in the context of your full clinical picture.
It's important to note that velocity numbers can vary between labs and equipment. What matters most is the interpretation by a qualified cardiologist who considers all values together, not any single number in isolation.
Intima-Media Thickness: The Early Warning Number
Many reports also include intima-media thickness (IMT) — a measurement of the thickness of the inner two layers of the carotid artery wall. IMT is measured in millimeters, typically at the far wall of the common carotid artery.
Normal IMT is generally considered below 0.9mm. Values between 0.9mm and 1.2mm suggest early atherosclerotic changes. Above 1.2mm is typically defined as plaque. IMT is valuable because it can identify early vascular aging and increased cardiovascular risk before significant plaque develops — giving patients and physicians time to intervene.
Plaque: What the Description Means
If plaque is present, the report will describe its location, size, and often its composition. Echogenic plaque (bright on ultrasound) is typically calcified and more stable. Hypoechoic plaque (dark on ultrasound) is softer and potentially more vulnerable to rupture — which carries higher short-term stroke risk.
The report may also describe whether the plaque surface is smooth or irregular. Irregular or ulcerated plaque surfaces are associated with higher embolic risk. Your cardiologist will factor plaque characteristics into the overall risk assessment alongside velocity measurements and stenosis estimates.
What Happens Next
If your report shows no significant disease, your cardiologist's letter will typically recommend a repeat study in 3–5 years depending on your risk factors. If moderate disease is found, more frequent monitoring — typically annually — and aggressive risk factor management are usually recommended. Significant stenosis above 70% generally warrants a vascular surgery consultation to discuss whether a preventive procedure is appropriate.
At BlackPoint Diagnostics, every carotid study is reviewed by a board-certified cardiologist who provides a written report with specific findings, risk stratification, and recommended follow-up. You receive plain-language results, not just raw numbers.
