How to Read Your Carotid Ultrasound Report

Your carotid ultrasound report arrives via encrypted email within 24 to 48 hours of your appointment. It contains measurements, clinical terminology, and conclusions that can be confusing without context. This guide explains what each section means in plain language so you can read your own report with confidence before discussing it with your physician.

The Basic Structure of a Carotid Report

A standard carotid duplex report covers four main areas: vessel anatomy, plaque characterization, stenosis quantification, and diastolic velocity assessment. Each carotid artery, right and left, is evaluated separately. The report describes the common carotid artery, the internal carotid artery, and the external carotid artery on each side.

Intima-Media Thickness (IMT): What Your Number Means

IMT measures the thickness of the innermost two layers of the carotid artery wall in millimeters. Normal IMT for most adults is below 0.9 mm. Values above 1.0 mm indicate significant wall thickening consistent with early atherosclerosis. IMT above 1.5 mm or focal thickening meeting specific criteria is classified as a plaque.

Your IMT is typically compared to age- and sex-matched reference ranges. A finding of IMT in the 75th percentile for your age means your arterial walls are thicker than 75 percent of people your age. This is clinically meaningful because it suggests accelerated arterial aging and an above-average atherosclerotic burden.

Plaque: What the Report Describes

When the report identifies plaque, it describes several characteristics. Location refers to which artery and at what anatomical landmark. Size refers to the dimensions of the plaque in millimeters. Echogenicity describes how the plaque appears on ultrasound: hyperechoic plaques are calcified and generally more stable, while hypoechoic or heterogeneous plaques may be softer and carry higher rupture risk. Surface characterization notes whether the plaque surface appears smooth or irregular.

The presence of plaque is not an emergency finding in the absence of significant stenosis. Many people have small stable carotid plaques that are monitored over time without intervention. The report tells your physician what is there, how it looks, and how to follow it.

Stenosis: Understanding the Percentage

If the report notes a stenosis, it is expressed as a percentage reduction in the arterial lumen. The commonly used classification is: less than 50 percent is mild stenosis, 50 to 69 percent is moderate, 70 to 99 percent is severe, and 100 percent is complete occlusion. The clinical threshold for intervention, typically stenting or endarterectomy, is generally severe stenosis of 70 percent or greater in symptomatic patients, or greater than 80 percent in asymptomatic patients. The American Heart Association emphasizes that up to 80% of strokes are preventable, making early detection through imaging critical.

Peak Systolic Velocity (PSV) and End Diastolic Velocity (EDV)

These are flow velocity measurements taken with Doppler ultrasound. Velocity increases when an artery is narrowed, similar to how water moves faster through a narrow nozzle. An internal carotid PSV above 125 cm/s suggests at least 50 percent stenosis. Above 230 cm/s typically indicates severe stenosis. These numbers allow the radiologist or cardiologist to quantify stenosis even when imaging alone is inconclusive.

The Impression and Recommendations Section

This is the most important part of your report. The reviewing cardiologist summarizes all findings into a clinical assessment and recommends a follow-up interval. Common recommendations include repeat imaging in one to two years for stable mild findings, referral to vascular surgery for severe stenosis, and correlation with symptoms if any are present. If no action is recommended and the report is negative or mildly abnormal, that is genuinely reassuring information.