VT Carotid & Vertebral Ultrasound 3 — Questions and Answers
Question 1: A hypoechoic, homogeneous plaque in the ICA is best described as:
- Calcified plaque with acoustic shadowing
- Soft or lipid-rich plaque associated with higher embolic risk (Correct answer)
- Heterogeneous plaque with intraplaque hemorrhage
- Stable fibrous plaque with low stroke risk
Correct answer: Soft or lipid-rich plaque associated with higher embolic risk
Hypoechoic homogeneous plaques are considered soft or lipid-rich and carry higher embolic risk compared to echogenic fibrous or calcified plaques.
Question 2: What is the recommended Doppler angle of insonation for carotid duplex velocity measurements?
- 0 degrees
- 30 degrees
- 60 degrees (Correct answer)
- 90 degrees
Correct answer: 60 degrees
A 60-degree Doppler angle is the standard for carotid duplex because it balances accuracy with practical beam-to-vessel angle constraints.
Question 3: In a patient with bilateral carotid stenosis, which hemodynamic change may occur in the contralateral CCA?
- Decreased PSV due to reduced cardiac output
- Increased PSV due to compensatory collateral flow (Correct answer)
- Reversal of diastolic flow
- No change in waveform morphology
Correct answer: Increased PSV due to compensatory collateral flow
Contralateral CCA PSV may increase as compensatory collateral circulation develops through the circle of Willis to supply the hemisphere with the more severe stenosis.
Question 4: Which ultrasound finding is most characteristic of carotid artery dissection?
- Calcified plaque at the carotid bulb
- Double lumen with an intimal flap (Correct answer)
- Increased IMT at the CCA bifurcation
- Turbulent color flow without a visible intimal tear
Correct answer: Double lumen with an intimal flap
Carotid dissection classically shows a double lumen separated by an echogenic intimal flap, with the false lumen often demonstrating slow or reversed flow.
Question 5: End-diastolic velocity (EDV) in the ICA is particularly useful because it:
- Is unaffected by cardiac output changes
- Correlates with the degree of distal cerebral resistance (Correct answer)
- Remains constant regardless of stenosis severity
- Is always higher than PSV in normal vessels
Correct answer: Correlates with the degree of distal cerebral resistance
EDV reflects downstream cerebrovascular resistance; in high-grade ICA stenosis, EDV rises markedly because the brain vasodilates to maintain perfusion pressure.
Question 6: Acoustic shadowing from a heavily calcified carotid plaque is problematic because it:
- Overestimates plaque size on B-mode imaging
- Prevents accurate velocity measurement within the calcified segment (Correct answer)
- Creates color aliasing artifacts downstream
- Causes mirror-image artifact in the adjacent jugular vein
Correct answer: Prevents accurate velocity measurement within the calcified segment
Dense calcification blocks the ultrasound beam and prevents Doppler sampling within and immediately distal to the calcified plaque, potentially obscuring significant stenosis.
Question 7: Which parameter is measured to assess intima-media thickness (IMT) for cardiovascular risk stratification?
- Distance from leading edge of lumen-intima to trailing edge of adventitia
- Distance from the outer wall to the inner wall of the CCA
- Distance from the leading edge of adventitia to the trailing edge of intima (Correct answer)
- Distance from the media-adventitia to the far wall lumen interface
Correct answer: Distance from the leading edge of adventitia to the trailing edge of intima
IMT is measured on the far wall from the leading edge of the media-intima interface to the trailing edge (lumen-intima interface), most commonly in the distal CCA.
VT Carotid & Vertebral Ultrasound 3
A hypoechoic, homogeneous plaque in the ICA is best described as: