Diagnostic ultrasound ( PDFDrive )

CHAPTER
26
The Extracranial Cerebral Vessels
Edward I. Bluth, Stephen I. Johnson, and Laurie Troxclair
SUMMARY OF KEY POINTS
• The combination of gray-scale, color-low Doppler,
and Doppler spectral analysis is highly accurate in
determining plaque characterization and degree of carotid
stenosis.
• Accurate diagnosis of carotid stenosis is critical for
patients who would beneit from surgical and
interventional treatment.
• Clinicians can accurately follow changes in noncritical
carotid stenosis or plaque using ultrasound.
• The assessment of the vertebral arteries is an integral
component of the carotid ultrasound examination.
However, the degree of stenosis of the vertebral arteries
cannot be accurately assessed.
• Carotid atherosclerotic plaque with resultant stenosis
usually involves the internal carotid artery within 2 cm of
the carotid bifurcation.
• Homogenous plaque, which is stable, has uniform echo
pattern with a smooth surface. The amount of
sonolucency is less than 50%.
• Heterogeneous plaque, which can be unstable, has a more
complex echo pattern with sonolucent areas of more than
50%.
• Either the consensus table by the Society of Radiologists
in Ultrasound or other standard reporting tables and criteria
can be used to grade carotid stenosis as long as there is
appropriate quality outcome feedback for accuracy.
CHAPTER OUTLINE
INTRODUCTION: INDICATIONS FOR
CAROTID ULTRASOUND
EXAMINATION
CAROTID ARTERY ANATOMY
CAROTID ULTRASOUND
EXAMINATION
CAROTID ULTRASOUND
INTERPRETATION
Visual Inspection of Gray-Scale Images
Vessel Wall Thickness and Intima-
Media Thickening
Plaque Characterization
Ultrasound Plaque Classiication
System
Plaque Ulceration
Gray-Scale Evaluation of Stenosis
Doppler Spectral Analysis
Standard Examination
Spectral Broadening
Pitfalls in Interpretation
High-Velocity Blood Flow Patterns
Color Doppler Ultrasound
Optimal Settings for Low-Flow
Vessel Evaluation
Advantages and Pitfalls
Power Doppler Ultrasound
Pitfalls and Adjustments
Internal Carotid Artery Occlusion
Follow-Up of Stenosis
Preoperative Strategies for Patients
With Carotid Artery Disease
Postoperative Ultrasound
Carotid Artery Stents and
Revascularization
Grading Carotid Intrastent
Restenosis
NONATHEROSCLEROTIC CAROTID
DISEASE
Pulsatile Neck Masses in the Carotid
Region
TRANSCRANIAL DOPPLER
SONOGRAPHY
VERTEBRAL ARTERY
Anatomy
Sonographic Technique and Normal
Examination
Subclavian Steal
Stenosis and Occlusion
INTERNAL JUGULAR VEINS
Sonographic Technique
Thrombosis
Acknowledgment
INTRODUCTION: INDICATIONS FOR
CAROTID ULTRASOUND
EXAMINATION
Stroke secondary to atherosclerotic disease is the third leading
cause of death in the United States. Many stroke victims survive
the catastrophic event with some degree of neurologic impairment
depending on collateral low. 1,2 Annually, stroke kills more than
130,000 people in the United States with an incidence of more
than 795,000 cases of cerebrovascular accident (CVA). 3,4 Ischemia
from severe, low-limiting stenosis caused by atherosclerotic
disease involving the extracranial carotid arteries is implicated
in 20% to 30% of strokes with a decreasing incidence due to
improved control of hypertension and hyperlipidemia with
medications. 3,5 An estimated 80% of CVAs are thromboembolic
in origin, oten with carotid plaque as the embolic source. 6
Cardioembolic stroke carries a higher risk of death, recurrent
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