Question 1: The correct answer is A) A stenosis in the brachiocephalic artery

Retrograde flow in the right vertebral artery is most commonly due to a significant stenosis or occlusion of the brachiocephalic artery. This condition can lead to blood flow reversal in the vertebral artery as collateral pathways develop to supply the right upper extremity.

Question 2: The correct Answer is C) A low-velocity, narrow residual lumen with a dampened waveform

A near-total occlusion (also called a “string sign”) is characterized by extremely low-velocity, dampened flow within a small residual lumen. Unlike a complete occlusion, where no flow is detected, near-occlusion requires careful Doppler optimization to confirm the presence of residual flow.

Question 3: The correct answer is B) 20 mmHg
A systolic blood pressure difference of 20 mmHg or greater between arms suggests the presence of a hemodynamically significant stenosis or occlusion in the subclavian or brachiocephalic artery. This finding is commonly associated with subclavian steal syndrome.

Question 4: The correct answer is D) Increasing the wall filters
To differentiate a nearly occluded vessel (string sign) from a completely occluded artery, it is useful to optimize color gain, decrease the Doppler scale, and use Power Doppler to enhance sensitivity to low flow. Increasing the wall filters would suppress low-velocity signals and is therefore not helpful in detecting residual flow.

Question 5: The correct answer is C) Pulsus Bisferiens
Pulsus bisferiens is a characteristic arterial waveform with two peaks in systole, commonly seen in patients with aortic regurgitation or hypertrophic obstructive cardiomyopathy. This finding is best observed in the carotid arteries.

Non-Invasive Cerebrovascular Interpretation (Extracranial)

Quiz: Practical Physics for the Ultrasound Interpreter