Carotid Stenosis: Evaluation with Doppler Ultrasound and its Role in Stroke Prevention
- Dr. Segnini
- Jan 8
- 2 min read
The Silent Risk
Carotid stenosis is the narrowing of the carotid arteries, the main vessels that supply blood to the brain. This narrowing, caused primarily by atherosclerosis (plaque buildup), is a critical risk factor for ischemic stroke . Doppler ultrasound is the first-line, non-invasive, and readily available imaging technique for its detection and quantification.
Why is Doppler Ultrasound Essential ?
Screening and Diagnosis: Identifies atherosclerotic plaques and measures the degree of obstruction in patients with risk factors (hypertension, diabetes, smoking) or symptoms such as cervical murmurs or transient ischemic attacks (TIAs).
Risk Classification: Quantifies the severity of the stenosis, which is crucial for management (medical treatment vs. surgical/ endovascular intervention ).
Plaque Characterization: It not only measures narrowing, but also assesses plaque morphology (stable vs. vulnerable), an independent prognostic factor.
Follow-up: Monitors disease progression or the effectiveness of treatments such as statins , and assesses patency after an intervention ( endarterectomy or stenting ).
Protocol and Key Ultrasound Findings:
A) Anatomical Evaluation (B-Mode - Gray Scale):
Visualization of the Plaque: It is identified as a thickening of the intima-media layer (>1.5 mm) that protrudes into the lumen of the vessel.
Plate Characterization:
Stable Plaque ( Fibrocalcific ): Hyperechoic (white), with posterior acoustic shadowing. Considered less prone to rupture.
Vulnerable or "Soft" Plate: Hypoechoic (black/gray), heterogeneous, with possible surface ulceration. Associated with a higher risk of embolization and stroke.
B) Hemodynamic Evaluation ( Color Doppler and Spectral-Pulsed Doppler ):
Color Doppler : Provides a visual map of blood flow, allowing quick identification of narrowing areas where the speed increases (areas of aliasing or color change).
Spectral (Pulsed) Doppler : This is the cornerstone of quantification. Blood velocity is measured at specific points. A stenosis causes an increase in velocity to maintain flow.
Stenosis Grading Criteria (based on velocity):
Normal/Light (<50%): Peak systolic velocity (PSV) <125 cm/s. Laminar flow.
Moderate (50-69%): VSP between 125 and 230 cm/s. Notable increase in speed and turbulence.
Severe (70-99%): A primary criterion is a pulse velocity ( PV) >230 cm/s . An elevated end-diastolic velocity (EDV) >100 cm/s and changes in distal internal carotid flow are also observed .
Total Occlusion (100%): Absence of detectable flow with Color and Spectral Doppler in the lumen of the vessel.
Limitations and Considerations:
Accuracy depends on the skill of the technician and a correct insonation angle (<60°).
It can be difficult in patients with complex anatomy, extensive calcifications (which block the signal), or low cardiac flows.
In complex cases, it is complemented with CT angiography or MR angiography .
Conclusion:
Doppler ultrasound Carotid artery ultrasound is an indispensable, safe, and effective tool in preventive vascular neurology. Its ability to diagnose, quantify, and characterize carotid stenosis makes it the initial study of choice for assessing stroke risk and guiding therapeutic decisions that can be vital for the patient.
Carotid Doppler Ultrasound
Dr. Jose Segnini, Radiologist / Diagnostic Medical Sonographer
MD Radiologist (Venezuela – Chile)
Board Certified Diagnostic Medical Sonographer (ARDMS, USA)
Mobile Ultrasound & Medical Supplies – Orlando, Florida
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