RVT - Registered Vascular Technologist Cerebrovascular Anatomy and Disease Questions and Answers 1 — Questions and Answers
Question 1: A 68-year-old male presents with episodes of dizziness, vertigo, and bilateral visual disturbances. A carotid duplex ultrasound reveals antegrade flow in both internal carotid arteries and the right vertebral artery. However, the left vertebral artery demonstrates sustained retrograde flow. What is the most likely diagnosis?
- Right subclavian steal syndrome
- Vertebrobasilar insufficiency
- Left subclavian steal syndrome (Correct answer)
- Bilateral carotid artery stenosis
Correct answer: Left subclavian steal syndrome
Subclavian steal syndrome is characterized by the reversal of blood flow in the vertebral artery on the same side as a significant stenosis or occlusion of the proximal subclavian artery. The retrograde flow in the left vertebral artery indicates that blood is being 'stolen' from the posterior circulation to supply the left arm, which is diagnostic of left subclavian steal syndrome.
Question 2: Which of the following is the first major branch of the internal carotid artery (ICA) after it enters the cranial cavity?
- Middle cerebral artery
- Anterior cerebral artery
- Posterior communicating artery
- Ophthalmic artery (Correct answer)
Correct answer: Ophthalmic artery
The ophthalmic artery is typically the first major branch arising from the supraclinoid segment of the internal carotid artery after it passes through the cavernous sinus and enters the cranial cavity. It supplies blood to the structures of the orbit.
Question 3: A vascular technologist is performing a Transcranial Doppler (TCD) examination through the transtemporal window. To identify the middle cerebral artery (MCA), what is the expected direction of blood flow relative to the transducer?
- Away from the transducer
- Bidirectional
- Antegrade (towards the transducer) (Correct answer)
- Variable depending on patient position
Correct answer: Antegrade (towards the transducer)
When insonating through the transtemporal window for a TCD exam, the ultrasound beam is typically aimed superiorly and slightly anteriorly. The middle cerebral artery (MCA) courses laterally from the circle of Willis, so its blood flow is directed towards the transducer, resulting in an antegrade or positive Doppler shift.
Question 4: According to the widely accepted SRU (Society of Radiologists in Ultrasound) consensus criteria for grading internal carotid artery stenosis, which of the following findings is most consistent with a stenosis of 70% or greater?
- Peak Systolic Velocity (PSV) of 125 cm/s
- Peak Systolic Velocity (PSV) greater than 230 cm/s (Correct answer)
- End-Diastolic Velocity (EDV) of 30 cm/s
- ICA/CCA PSV ratio of 1.5
Correct answer: Peak Systolic Velocity (PSV) greater than 230 cm/s
The SRU consensus criteria use a Peak Systolic Velocity (PSV) of greater than 230 cm/s as a primary parameter to diagnose an internal carotid artery stenosis of 70% or greater, up to near occlusion. Additional parameters like an End-Diastolic Velocity (EDV) >100 cm/s and an ICA/CCA PSV ratio >4.0 are also used to confirm high-grade stenosis.
Question 5: A patient is referred for a cerebrovascular ultrasound due to symptoms of vertebrobasilar insufficiency (VBI). Which of the following symptoms is LEAST likely to be associated with this condition?
- Vertigo and dizziness
- Unilateral facial droop (Correct answer)
- Bilateral vision loss (diplopia)
- Drop attacks (sudden leg weakness)
Correct answer: Unilateral facial droop
Vertebrobasilar insufficiency results from reduced blood flow to the posterior circulation of the brain. Symptoms typically involve structures supplied by the vertebral and basilar arteries, such as the cerebellum and brainstem, leading to vertigo, vision changes, and coordination issues. A unilateral facial droop is a classic symptom of anterior circulation stroke, often involving the middle cerebral artery territory, not typically isolated in VBI.
Question 6: What is the primary purpose of the Circle of Willis in the cerebrovascular system?
- To supply blood to the cerebellum
- To act as the main venous drainage system
- To provide a collateral pathway for cerebral perfusion (Correct answer)
- To regulate intracranial pressure
Correct answer: To provide a collateral pathway for cerebral perfusion
The Circle of Willis is an arterial anastomosis at the base of the brain that connects the anterior (internal carotid arteries) and posterior (vertebrobasilar system) circulations. Its primary function is to provide redundancy and collateral blood flow, which can help maintain cerebral perfusion if a major contributing artery becomes stenosed or occluded.
RVT - Registered Vascular Technologist Cerebrovascular Anatomy and Disease Questions and Answers 1
A 68-year-old male presents with episodes of dizziness, vertigo, and bilateral visual disturbances.
A carotid duplex ultrasound reveals antegrade flow in both internal carotid arteries and the right vertebral artery.
However, the left vertebral artery demonstrates sustained retrograde flow.
What is the most likely diagnosis?