What test is used to check for atherosclerosis of the carotid artery?

Diagnostic Testing for Carotid Artery Atherosclerosis

Carotid duplex ultrasonography is the recommended first-line test for detecting atherosclerosis of the carotid artery due to its non-invasive nature, high accuracy, and wide availability. 1, 2

Primary Diagnostic Approach

Carotid Duplex Ultrasonography

• Combines 2-dimensional real-time imaging with Doppler flow analysis
• Measures blood flow velocity as an indicator of stenosis severity
• Key parameters:
  • Peak systolic velocity in the internal carotid artery
  • Ratio of peak systolic velocity in internal carotid artery to ipsilateral common carotid artery
• Does not directly measure arterial diameter but uses velocity as a surrogate 1

Secondary/Confirmatory Testing

When carotid duplex ultrasonography results are equivocal or non-diagnostic:

1. Magnetic Resonance Angiography (MRA)

   • Provides images of both cervical and intracranial portions of carotid artery
   • May overestimate degree of stenosis
   • Contraindicated in patients with renal dysfunction due to risk of nephrogenic systemic fibrosis 1

2. Computed Tomography Angiography (CTA)

   • Evaluates both extracranial and intracranial circulation
   • Disadvantages include radiation exposure and need for contrast material
   • Arterial calcification may interfere with accurate stenosis measurement 1

3. Catheter-Based Contrast Angiography

   • Historical gold standard against which other imaging modalities are compared
   • Reserved for cases where noninvasive imaging is inconclusive or discordant
   • Current permanent stroke complication rate <0.2% 1

Indications for Carotid Imaging

Recommended:

• Patients with focal neurological symptoms corresponding to carotid territory 1, 2
• Cervical bruit in asymptomatic patients 1, 2
• Follow-up of known stenosis >50% in asymptomatic individuals 1
• Vascular assessment in patients with multiple atherosclerosis risk factors 1
• Stroke risk assessment in patients with coronary artery disease or peripheral arterial disease 1
• Amaurosis fugax or hemispheric TIA 1
• Stroke in candidates for carotid revascularization 1

Not Recommended:

• Routine screening of asymptomatic patients without risk factors 1, 2
• Evaluation of patients with neurological disorders unrelated to focal cerebral ischemia 1, 2

Quality Assurance Considerations

• Correlation of findings from multiple imaging modalities should be part of quality assurance programs 1, 2
• Comparison of noninvasive imaging with catheter angiography when available 1
• Regular validation of laboratory accuracy and technician performance 2

Pitfalls and Caveats

• Duplex ultrasonography may have difficulty differentiating high-grade stenosis from complete occlusion 1, 3
• Accuracy varies between laboratories; certification programs help standardize performance 1, 2
• When high-grade stenosis is suspected but internal carotid artery cannot be clearly identified, additional imaging is warranted 3
• The combination of duplex ultrasound and MRA is more accurate than either test alone when results are concordant 1