CCI - Cardiovascular Credentialing International Cerebrovascular Duplex Examinations Questions and Answers — Questions and Answers
Question 1: A sonographer performs a carotid duplex exam and obtains the following measurements in the left internal carotid artery (ICA): Peak Systolic Velocity (PSV) = 255 cm/s, End-Diastolic Velocity (EDV) = 110 cm/s, and an ICA/CCA PSV ratio of 4.5. Based on the Society of Radiologists in Ultrasound (SRU) consensus criteria, what is the estimated degree of stenosis?
- <50% stenosis
- 50-69% stenosis
- ≥70% stenosis to near occlusion (Correct answer)
- Total occlusion
Correct answer: ≥70% stenosis to near occlusion
According to the widely accepted SRU consensus criteria, an ICA Peak Systolic Velocity (PSV) greater than 230 cm/s is a primary indicator for a stenosis of ≥70%. [17, 26] The additional findings of an End-Diastolic Velocity (EDV) >100 cm/s and an ICA/CCA PSV ratio >4.0 further support this conclusion, placing the stenosis in the ≥70% to near occlusion category. [17]
Question 2: Which of the following findings is most definitive for identifying the External Carotid Artery (ECA) as distinct from the Internal Carotid Artery (ICA)?
- A higher resistance spectral waveform
- Visualization of cervical branches (Correct answer)
- Smaller diameter compared to the ICA
- Anteromedial location relative to the ICA
Correct answer: Visualization of cervical branches
While the ECA typically has a higher resistance waveform, is often smaller, and is usually located anteromedial to the ICA, these characteristics can be variable. The most definitive and unambiguous sonographic finding to identify the ECA is the visualization of its branches, such as the superior thyroid, ascending pharyngeal, or facial arteries, originating from it in the neck. [1, 3, 7]
Question 3: A duplex ultrasound of the vertebral arteries reveals sustained retrograde (reversed) flow in the left vertebral artery. This finding is a classic sign of which condition?
- High-grade stenosis of the left internal carotid artery
- Occlusion or high-grade stenosis of the proximal left subclavian artery (Correct answer)
- Occlusion of the basilar artery
- Stenosis of the right brachiocephalic artery
Correct answer: Occlusion or high-grade stenosis of the proximal left subclavian artery
Sustained retrograde flow in a vertebral artery is the hallmark of subclavian steal syndrome. This occurs when there is a severe stenosis or occlusion in the subclavian artery proximal to the origin of the vertebral artery. [9, 20] The pressure drop in the arm causes blood to flow down the vertebral artery (in a reverse direction) to supply the ischemic arm, 'stealing' it from the cerebral circulation. [9, 24]
Question 4: During a carotid evaluation, the sonographer observes a low-velocity, delayed systolic upstroke, and rounded systolic peak in the left Common Carotid Artery (CCA). This waveform morphology, known as 'tardus parvus,' suggests a significant stenosis in which location?
- Left Internal Carotid Artery (ICA)
- Left Vertebral Artery
- Left Subclavian or Brachiocephalic Artery (Correct answer)
- Right Common Carotid Artery (CCA)
Correct answer: Left Subclavian or Brachiocephalic Artery
A 'tardus parvus' waveform indicates the dampening effect of a significant stenosis or occlusion proximal (upstream) to the point of sampling. [14, 19] Since the waveform is observed in the left CCA, the flow obstruction must be located more proximally, such as in the left subclavian artery or the brachiocephalic (innominate) artery, which gives rise to the right-sided vessels. [8, 16]
Question 5: A sonographer identifies atherosclerotic plaque in the carotid bifurcation that appears brightly echogenic and produces a strong posterior acoustic shadow, obscuring the vessel wall behind it. How is this type of plaque best characterized?
- Soft
- Homogeneous
- Calcified
- Ulcerated (Correct answer)
Correct answer: Ulcerated
Markedly hyperechoic (bright) plaque that causes posterior acoustic shadowing is characteristic of calcified plaque. [6, 12] The dense calcium deposits do not allow the ultrasound beam to pass through, creating a shadow behind the plaque. Soft plaques are typically hypoechoic, and homogeneous plaques have a uniform texture without significant shadowing. [6]
Question 6: A patient with stroke-like symptoms undergoes a carotid duplex scan. In the proximal ICA, the sonographer notes a very narrow, trickle-flow channel on color Doppler. Spectral Doppler reveals a markedly reduced peak systolic velocity of 40 cm/s and an end-diastolic velocity of 15 cm/s. These findings are most indicative of:
- 50-69% stenosis
- Near occlusion (Correct answer)
- A normal, small vessel
- Total occlusion
Correct answer: Near occlusion
While high velocities are expected with most severe stenoses, a pre-occlusive or 'near occlusion' state can result in a paradoxical drop in velocities due to the extremely high resistance and low volume of flow. [23] The presence of a thin 'string sign' on color Doppler combined with very low, dampened velocities is the classic presentation of a near occlusion, which is critical to differentiate from a total occlusion where no flow would be detected. [22, 27]
CCI - Cardiovascular Credentialing International Cerebrovascular Duplex Examinations Questions and Answers
A sonographer performs a carotid duplex exam and obtains the following measurements in the left internal carotid artery (ICA): Peak Systolic Velocity (PSV) = 255 cm/s, End-Diastolic Velocity (EDV) = 110 cm/s, and an ICA/CCA PSV ratio of 4.5.
Based on the Society of Radiologists in Ultrasound (SRU) consensus criteria, what is the estimated degree of stenosis?