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RPVI practice questions

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Question 1Vascular ultrasound interpretation

A carotid duplex waveform shows a low-resistance spectral pattern with continuous forward diastolic flow. Which vessel does this most likely represent?

  1. Common carotid artery proximal to the bifurcation
  2. Superior thyroid artery
  3. Internal carotid artery Correct answer.
  4. External carotid artery

Explanation

The internal carotid artery supplies the low-resistance cerebral circulation, so it shows broad systole and continuous forward diastolic flow. The external carotid supplies a higher-resistance vascular bed and typically has reduced or absent early diastolic flow.

Question 2Vascular ultrasound interpretation

During a lower extremity venous duplex, augmentation of flow after distal limb compression is absent in a segment. What does this finding most directly indicate?

  1. Competent valves with normal reflux prevention
  2. Normal respiratory phasicity
  3. Obstruction between the point of compression and the sample volume Correct answer.
  4. Arterial insufficiency distal to the cuff

Explanation

Failure to augment indicates a barrier to flow between the compression point and the Doppler sample, typically a thrombus or other obstruction. Augmentation assesses continuity of the venous segment, not valve competence.

Question 3Vascular ultrasound interpretation

An ankle-brachial index is calculated as 0.65 in a symptomatic patient. How is this result best classified?

  1. Severely abnormal
  2. Mildly abnormal
  3. Normal
  4. Moderately abnormal Correct answer.

Explanation

An ABI of 0.65 falls in the moderate range (0.41 to 0.90), indicating significant peripheral arterial disease. Values above 0.90 are normal and 0.40 or below indicate severe disease.

Question 4Vascular ultrasound interpretation

Which finding on a venous duplex study is the most reliable direct sign of acute deep vein thrombosis?

  1. Continuous flow in the common femoral vein
  2. Loss of venous phasicity
  3. Noncompressibility of the vein Correct answer.
  4. Increased venous diameter with respiration

Explanation

Noncompressibility of the vein under probe pressure is the most reliable direct criterion for acute deep vein thrombosis. Secondary signs such as loss of phasicity or venous dilation are supportive but less specific.

Question 5Vascular ultrasound interpretation

A renal artery Doppler spectrum shows a tardus-parvus waveform distal to a stenosis. Which feature characterizes this pattern?

  1. Pulsus alternans with alternating amplitudes
  2. High-resistance flow with reversed diastole
  3. Delayed systolic acceleration with rounded peak Correct answer.
  4. Rapid systolic upstroke with early systolic peak

Explanation

Tardus-parvus describes a dampened downstream waveform with delayed systolic acceleration (prolonged acceleration time) and a rounded, low-amplitude peak. It reflects reduced perfusion pressure beyond a significant stenosis.

Question 6Vascular ultrasound interpretation

Which parameter is used to estimate the severity of an internal carotid artery stenosis from a spectral Doppler tracing?

  1. Resistive index
  2. Pulsatility index
  3. Peak systolic velocity Correct answer.
  4. Acceleration time

Explanation

Peak systolic velocity is the primary Doppler parameter used to grade internal carotid stenosis, often combined with end-diastolic velocity and the ICA/CCA ratio. Resistive and pulsatility indices describe waveform shape rather than stenosis severity.

Question 7Vascular ultrasound interpretation

What does an abnormal bidirectional flow pattern in the vertebral vein most likely reflect?

  1. Arteriovenous fistula formation
  2. Retrograde flow from a central venous obstruction Correct answer.
  3. Normal respiratory variation
  4. Normal cardiac pulsatility transmitted to the vein

Explanation

Bidirectional or continuous non-phasic flow in the vertebral vein can indicate altered central venous hemodynamics such as obstruction, causing flow to reverse during parts of the cardiac cycle. Normal vertebral venous flow is phasic and predominantly unidirectional.

Question 8Vascular ultrasound interpretation

A patient has an ABI of 1.45 with noncompressible tibial arteries and symptoms of claudication. Which additional test best assesses disease severity?

  1. Toe-brachial index Correct answer.
  2. Segmental plethysmography of the thigh only
  3. Continuous-wave Doppler of the dorsalis pedis alone
  4. Repeat ABI with a larger cuff

Explanation

When the ABI is falsely elevated by medial calcinosis, the toe-brachial index is preferred because digital arteries are less often affected by calcification. It provides a more reliable assessment of perfusion in this setting.

Question 9Vascular ultrasound interpretation

On a carotid duplex, a plaque produces a focal velocity increase but the stenosis appears mild on grayscale imaging. What is the most appropriate interpretation?

  1. The finding is artifactual and should be ignored
  2. The velocity elevation confirms severe stenosis
  3. The velocity may be elevated by compensatory flow or contralateral disease and should be correlated Correct answer.
  4. The grayscale appearance always overrides Doppler findings

Explanation

Velocity elevation can be influenced by compensatory flow increases, contralateral occlusion, or systemic factors, so it must be correlated with grayscale and color findings. Neither imaging nor Doppler alone should be interpreted in isolation.

Question 10Vascular ultrasound interpretation

A venous duplex shows continuous, non-phasic flow in the common femoral vein that does not vary with respiration. Which condition is the most likely cause?

  1. Distal calf muscle pump failure
  2. Isolated perforator incompetence
  3. Normal variant in thin patients
  4. Proximal venous obstruction Correct answer.

Explanation

Loss of respiratory phasicity with continuous flow suggests a proximal obstruction dampening the transmission of central venous pressure changes. Distal problems such as perforator incompetence do not abolish phasicity in the common femoral vein.

Question 11Vascular ultrasound interpretation

During a segmental pressure study, a pressure drop of 25 mm Hg is identified between the upper thigh and lower thigh cuffs. What does this most likely indicate?

  1. Popliteal artery stenosis
  2. Superficial femoral artery stenosis Correct answer.
  3. Iliac artery stenosis
  4. Tibial artery stenosis

Explanation

A significant pressure gradient between adjacent thigh cuffs localizes disease to the segment between them, which corresponds to the superficial femoral artery. Iliac disease would appear at the high-thigh level, and popliteal or tibial disease would appear at lower cuff levels.

Question 12Vascular ultrasound interpretation

A carotid duplex demonstrates an internal carotid artery with no detectable flow and a distal string sign on angiography. What does the string sign represent?

  1. An artifact from transducer angulation
  2. Complete chronic occlusion with no residual flow
  3. A near-total occlusion with a tiny residual lumen Correct answer.
  4. A normal variant of the carotid bulb

Explanation

The string sign describes a very narrow residual lumen in a near-total occlusion, allowing only a thin trickle of contrast or flow. It indicates critical stenosis rather than complete occlusion.

Question 13Vascular ultrasound interpretation

Which Doppler finding best distinguishes a hemodynamically significant renal artery stenosis from a non-significant one?

  1. Peak systolic velocity below 100 cm/s
  2. Loss of diastolic flow
  3. Resistive index above 0.7
  4. Peak systolic velocity above 180 to 200 cm/s with post-stenotic turbulence Correct answer.

Explanation

A peak systolic velocity exceeding roughly 180 to 200 cm/s, often with post-stenotic turbulence and a high renin ratio, suggests hemodynamically significant renal artery stenosis. Lower velocities are generally not significant.

Question 14Vascular ultrasound interpretation

A patient with a dialysis access graft has a flow volume of 250 mL/min and a systolic pressure of 60 mm Hg at the venous anastomosis. What is the most likely interpretation?

  1. Normal functioning graft
  2. Access stenosis or failing graft Correct answer.
  3. Artifact from improper angle correction
  4. Expected finding in a mature fistula

Explanation

A flow volume below 500 to 600 mL/min and a low intra-access pressure suggest stenosis or a failing access that may require intervention. Normal access flow is typically much higher.

Question 15Vascular ultrasound interpretation

On a transcranial Doppler, which finding suggests vasospasm after subarachnoid hemorrhage?

  1. Mean flow velocity above 120 cm/s in the middle cerebral artery Correct answer.
  2. Mean flow velocity below 40 cm/s in the middle cerebral artery
  3. Increased pulsatility index with low velocities
  4. Loss of the basilar artery signal

Explanation

Elevated mean flow velocities in the middle cerebral artery, typically above 120 cm/s, suggest vasospasm, with higher velocities indicating more severe spasm. Low velocities or increased pulsatility suggest other processes.

Question 16Vascular ultrasound interpretation

A lower extremity arterial duplex shows a triphasic waveform proximal to a stenosis and a monophasic waveform distal to it. What does the monophasic distal waveform indicate?

  1. Venous contamination of the signal
  2. Normal compensatory flow
  3. Dampened flow from a hemodynamically significant stenosis Correct answer.
  4. Improved collateral flow

Explanation

A change from triphasic to monophasic flow across a stenosis indicates hemodynamic damping from a significant lesion. The loss of the reverse-flow phase reflects reduced distal resistance and pressure.

Question 17Vascular ultrasound interpretation

Which finding on a venous duplex is most consistent with chronic post-thrombotic changes rather than acute thrombosis?

  1. Loss of color fill in a normal-caliber vein
  2. A thin, echogenic web with partial compressibility and collateral veins Correct answer.
  3. Echogenic material filling a dilated vein with no compression
  4. Acute intraluminal filling defect with soft edges

Explanation

Chronic post-thrombotic changes include webs, synechiae, thickened walls, partial compressibility, and collateral formation. Acute thrombosis typically appears as a soft, hypoechoic filling defect with a dilated vein.

Question 18Vascular ultrasound interpretation

A carotid duplex shows a peak systolic velocity of 130 cm/s in the internal carotid artery with a normal end-diastolic velocity and no plaque. How should this be interpreted?

  1. Subclavian steal syndrome
  2. Normal or mildly elevated velocity without significant stenosis Correct answer.
  3. Severe stenosis requiring urgent intervention
  4. Complete occlusion

Explanation

A peak systolic velocity of 130 cm/s without plaque or elevated end-diastolic velocity is generally within the normal or mildly elevated range and does not indicate significant stenosis. Velocity thresholds must be interpreted with imaging findings.

Question 19Vascular ultrasound interpretation

A patient has a high-grade internal carotid stenosis. Which additional Doppler finding would most increase confidence in a hemodynamically significant lesion?

  1. Normal waveform distal to the stenosis
  2. Reduced peak systolic velocity
  3. Increased end-diastolic velocity and ICA/CCA ratio Correct answer.
  4. Absent spectral broadening

Explanation

Elevated end-diastolic velocity and an increased ICA/CCA ratio support the presence of a hemodynamically significant stenosis. These parameters reflect the pressure gradient across the lesion.

Question 20Vascular ultrasound interpretation

A venous duplex demonstrates reflux in the great saphenous vein lasting 0.8 seconds after distal compression. What is the most appropriate interpretation?

  1. Artifact from patient positioning
  2. Pathologic superficial venous reflux Correct answer.
  3. Normal finding in the deep system
  4. Reflux in the deep femoral vein

Explanation

Reflux in the superficial veins lasting longer than about 0.5 seconds is considered pathologic. A duration of 0.8 seconds in the great saphenous vein supports superficial venous incompetence.

Question 21Vascular ultrasound interpretation

A patient with suspected median arcuate ligament syndrome has a celiac artery velocity that increases markedly with expiration. What is the physiologic basis for this finding?

  1. Reduced splanchnic resistance during expiration
  2. Artifact from respiratory motion
  3. Increased cardiac output during expiration
  4. Compression of the celiac artery by the median arcuate ligament during expiration Correct answer.

Explanation

In median arcuate ligament syndrome, the ligament compresses the celiac artery, and the compression is typically worse during expiration as the diaphragm and aorta move. This produces a characteristic velocity increase with expiration.

Question 22Vascular ultrasound interpretation

In a patient with a suspected subclavian steal, which Doppler finding confirms the diagnosis?

  1. Normal triphasic vertebral waveform
  2. Retrograde vertebral flow during systole Correct answer.
  3. Absent vertebral flow only during diastole
  4. Antegrade vertebral flow with increased velocity

Explanation

Subclavian steal is confirmed by retrograde vertebral artery flow, which occurs when a proximal subclavian stenosis or occlusion reverses the pressure gradient. The flow may be partially or completely reversed depending on severity.

Question 23Vascular ultrasound interpretation

A carotid duplex shows a focal velocity increase in the common carotid artery with a normal internal carotid velocity and a bruit. What is the most likely explanation?

  1. Internal carotid stenosis
  2. Common carotid stenosis or tortuosity Correct answer.
  3. Vertebral artery stenosis
  4. Aortic valve stenosis

Explanation

A focal velocity increase in the common carotid artery with normal internal carotid velocities localizes the lesion to the common carotid or a tortuous segment. Internal carotid stenosis would elevate velocities in the internal carotid artery.

Question 24Vascular ultrasound interpretation

Which Doppler parameter is most useful for detecting a hemodynamically significant stenosis in a lower extremity bypass graft?

  1. Pulsatility index in the native artery
  2. Color saturation of the graft
  3. Peak systolic velocity and velocity ratio across the graft Correct answer.
  4. Resistive index at the proximal anastomosis

Explanation

Peak systolic velocity and the velocity ratio across a graft are used to detect significant stenosis, with a focal velocity increase suggesting a failing graft. Resistive and pulsatility indices are less specific for focal stenosis.

Question 25Vascular ultrasound interpretation

A patient has a normal ABI but symptoms of claudication that resolve with rest. Which test is most likely to reveal exercise-induced disease?

  1. Venous duplex of the lower extremity
  2. Exercise treadmill ABI testing Correct answer.
  3. Toe photoplethysmography at rest
  4. Resting duplex of the dorsalis pedis

Explanation

Exercise ABI testing can unmask hemodynamically significant disease that is not apparent at rest by demonstrating a post-exercise pressure drop. Resting studies may be normal in mild or compensated disease.

Question 26Vascular ultrasound interpretation

On a normal lower extremity arterial spectral Doppler tracing, which waveform feature indicates a low-resistance vascular bed distal to the insonation site?

  1. Early diastolic flow reversal followed by a second forward phase
  2. A prolonged systolic acceleration time with a rounded peak
  3. Absent diastolic flow with a sharp systolic upstroke
  4. Continuous forward flow throughout diastole Correct answer.

Explanation

Low-resistance beds such as the renal, hepatic, and internal carotid circulations maintain forward flow in diastole because downstream demand remains high throughout the cardiac cycle. High-resistance peripheral limb arteries instead show triphasic flow with early diastolic reversal. Diastolic reversal therefore signals a high-resistance bed, not a low-resistance one.

Question 27Vascular ultrasound interpretation

A venous duplex of the lower extremity is performed with the patient supine. Which maneuver is most appropriate to assess whether common femoral vein flow is phasic?

  1. Elevate the limb above the level of the heart
  2. Have the patient take a deep inspiration Correct answer.
  3. Augment flow with a distal manual squeeze
  4. Ask the patient to perform a Valsalva maneuver

Explanation

Phasicity reflects transmission of right heart and respiratory pressure changes to the venous system, so it is assessed during quiet respiration or a deep breath. Loss of phasicity suggests an obstruction between the insonated vein and the heart. Distal augmentation and Valsalva test different physiologic properties.

Question 28Vascular ultrasound interpretation

Which finding on a duplex ultrasound most directly confirms that a palpable abdominal mass is an abdominal aortic aneurysm rather than a tortuous aorta?

  1. Peak systolic velocity above 100 cm/s in the aorta
  2. Anteroposterior outer-to-outer diameter exceeding 3 cm Correct answer.
  3. Loss of the normal triphasic waveform in the common iliac arteries
  4. An intimal echo separating two lumens within the aortic wall

Explanation

An aneurysm is defined by focal dilation, conventionally an anteroposterior outer-wall-to-outer-wall diameter of 3 cm or more in the infrarenal aorta. Tortuosity produces lateral deviation without true dilation. Velocity and waveform changes are indirect and do not define aneurysmal enlargement.

Question 29Vascular ultrasound interpretation

During a carotid duplex, which vessel identification feature most reliably distinguishes the external carotid artery from the internal carotid artery?

  1. Branches in the neck and a higher-resistance waveform Correct answer.
  2. Presence of a visible valve at its origin
  3. Low-resistance waveform with continuous diastolic flow
  4. Larger caliber at the bifurcation

Explanation

The external carotid artery gives off cervical branches such as the superior thyroid and facial arteries and typically supplies a higher-resistance territory, producing a sharper upstroke with less diastolic flow. The internal carotid has no cervical branches and shows a low-resistance pattern. Caliber alone is unreliable because the internal carotid is usually larger but not always.

Question 30Vascular ultrasound interpretation

A duplex examination shows a focal doubling of peak systolic velocity across the origin of the superficial femoral artery with poststenotic turbulence. How is the degree of stenosis best categorized by velocity criteria?

  1. A velocity ratio of 2:1 always indicates a stenosis greater than 75 percent
  2. A velocity ratio of 2:1 generally indicates a stenosis of about 50 percent Correct answer.
  3. A velocity ratio of 2:1 corresponds to a stenosis of less than 20 percent
  4. A velocity ratio of 2:1 indicates an occlusion of the vessel

Explanation

In peripheral arterial duplex, a peak systolic velocity ratio of approximately 2:1 between the stenosis and the adjacent normal segment corresponds to a hemodynamically significant stenosis near 50 percent. Ratios of about 3:1 or greater suggest stenoses above 75 percent, and occlusion shows no flow. The ratio must be interpreted with the poststenotic waveform.

Question 31Vascular ultrasound interpretation

A patient with unilateral leg swelling undergoes venous duplex. The popliteal vein is fully compressible, but the common femoral vein shows echogenic material that does not compress and no detectable spontaneous flow. What is the most appropriate interpretation?

  1. Normal vein with slow flow from limb positioning
  2. Acute thrombosis involving the common femoral vein Correct answer.
  3. Artifact from excessive transducer pressure
  4. Chronic post-thrombotic thickening without obstruction

Explanation

Failure to compress a vein plus intraluminal echogenic material and absent spontaneous flow indicates acute thrombus. Acute thrombus typically distends the vein and is hypoechoic, whereas chronic changes produce a small, scarred, partially compressible vein with collateral flow. The combination of noncompressibility and absent flow supports an acute obstructive event.

Question 32Vascular ultrasound interpretation

A renal duplex is performed on a patient with hypertension. Which combination of findings best supports a hemodynamically significant renal artery stenosis?

  1. Peak systolic velocity of 120 cm/s at the ostium with a normal distal waveform
  2. Peak systolic velocity of 250 cm/s at the ostium with a tardus-parvus distal waveform Correct answer.
  3. Resistive index of 0.85 in the renal parenchyma with symmetric kidney sizes
  4. Absent diastolic flow in the renal vein during inspiration

Explanation

A markedly elevated peak systolic velocity at the stenosis, together with downstream waveform damping (tardus-parvus), indicates a pressure-reducing lesion. The distal change reflects reduced perfusion beyond the narrowing. Velocity alone at a single point can be misleading without the downstream effect.

Question 33Vascular ultrasound interpretation

A patient with a clotted hemodialysis access graft is evaluated. Which parameter is most useful for detecting access outflow stenosis before thrombosis?

  1. Peak systolic velocity in the brachial artery
  2. Static venous pressure measured at the dialysis machine
  3. Intra-access flow volume measured by duplex Correct answer.
  4. Graft diameter measured by grayscale imaging

Explanation

Access flow volume measured by duplex is a validated surveillance parameter, with flows below roughly 500 to 600 mL/min raising concern for outflow stenosis. Declining flow over time predicts thrombosis. Static pressures and diameter are less directly predictive.

Question 34Vascular ultrasound interpretation

On a carotid duplex, a patient has a peak systolic velocity of 90 cm/s in the internal carotid artery but the spectral waveform is damped with a prolonged acceleration time. What does this pattern most likely indicate?

  1. A proximal obstruction such as a common carotid or innominate lesion Correct answer.
  2. An occlusion of the internal carotid artery distal to the sample volume
  3. A normal internal carotid artery with low cardiac output
  4. A severe stenosis at the insonation site

Explanation

A damped, tardus-parvus waveform with prolonged acceleration time reflects reduced driving pressure upstream of the sample site. A proximal lesion in the common carotid or innominate artery produces this pattern. A focal stenosis at the sample site would instead raise local velocity.

Question 35Vascular ultrasound interpretation

A transcranial Doppler of the middle cerebral artery shows a mean velocity of 180 cm/s in a patient after subarachnoid hemorrhage. Which additional finding most supports vasospasm over hyperemia?

  1. An elevated Lindegaard ratio comparing intracranial to extracranial velocity Correct answer.
  2. Increased velocity in the extracranial internal carotid artery
  3. A low pulsatility index with globally elevated velocities
  4. Symmetric velocities in both middle cerebral arteries

Explanation

The Lindegaard ratio compares middle cerebral artery velocity to extracranial internal carotid velocity, distinguishing true vasospasm from generalized hyperemia. A ratio above about 3 supports vasospasm. Hyperemia raises velocities in both the intracranial and extracranial segments proportionally.

Question 36Vascular ultrasound interpretation

During a lower extremity venous reflux study, the superficial and deep systems are evaluated with distal compression and rapid release. Which finding indicates a hemodynamically important incompetent perforator?

  1. Outward flow lasting more than 0.5 seconds through the fascia Correct answer.
  2. Absent flow with the limb dependent
  3. Bidirectional flow lasting less than 0.2 seconds
  4. Inward flow during calf muscle systole only

Explanation

Perforator incompetence is defined by outward flow from the deep to the superficial system lasting longer than 0.5 seconds after distal compression or release. Brief bidirectional flow is a normal finding related to muscle pump action. Sustained outward flow indicates failure of the perforator valve.

Question 37Vascular ultrasound interpretation

A patient is evaluated for thoracic outlet syndrome. Duplex of the subclavian vein is performed with the arm in provocative positions. Which finding supports venous thoracic outlet compression?

  1. A doubling of peak systolic velocity in the subclavian artery with arm abduction
  2. A triphasic waveform in the subclavian artery during neutral position
  3. Continuous forward flow in the axillary vein during arm rest
  4. Focal narrowing of the subclavian vein with flow acceleration and loss of phasicity Correct answer.

Explanation

Venous thoracic outlet syndrome produces focal compression of the subclavian vein, seen as narrowing, localized velocity increase, and loss of phasicity with provocative positioning. Arterial compression would instead produce focal arterial velocity elevation. Findings must be reproduced with the arm in the provocative position.

Question 38Vascular ultrasound interpretation

A patient has a pulsatile abdominal mass and duplex shows a 3.2 cm infrarenal aorta with a focal saccular outpouching and a thin wall. Which feature most increases concern for imminent rupture?

  1. Saccular morphology with a focal thin-walled outpouching Correct answer.
  2. Anteroposterior diameter of 3.2 cm
  3. Peak systolic velocity of 80 cm/s in the sac
  4. Presence of mural thrombus lining the sac

Explanation

Saccular aneurysms and focal thin-walled outpouchings carry a higher rupture risk than similarly sized fusiform aneurysms. Diameter remains the strongest overall predictor, but morphology modifies risk. Mural thrombus is common and not itself a rupture indicator.

Question 39Vascular ultrasound interpretation

A carotid duplex is performed on a patient with a known severe internal carotid stenosis. Which finding indicates that the stenosis may be underestimated by peak systolic velocity?

  1. A near-occlusive lesion with markedly reduced flow and a distal string sign Correct answer.
  2. A focal aliasing artifact at the stenosis origin
  3. A very high end-diastolic velocity across the stenosis
  4. A poststenotic velocity that is higher than the prestenotic velocity

Explanation

Near-occlusive lesions can produce low or undetectable velocities because flow is critically reduced, so velocity criteria underestimate severity. The presence of a distal string sign or markedly damped poststenotic flow should prompt caution. Very high velocities generally indicate tighter stenosis rather than underestimation.

Question 40Vascular ultrasound interpretation

A patient with suspected chronic mesenteric ischemia undergoes duplex after an overnight fast. Which finding best supports a hemodynamically significant superior mesenteric artery stenosis?

  1. Peak systolic velocity above 275 cm/s at the origin with poststenotic damping Correct answer.
  2. End-diastolic velocity of 30 cm/s in the distal superior mesenteric artery
  3. Loss of the normal low-resistance waveform in the fasting state
  4. Peak systolic velocity of 150 cm/s at the origin with a normal poststenotic waveform

Explanation

A superior mesenteric artery peak systolic velocity above roughly 275 cm/s suggests a hemodynamically significant stenosis. Poststenotic waveform damping further supports a pressure-reducing lesion. Fasting status is important because postprandial hyperemia alters velocities.

Question 41Cerebrovascular testing and interpretation

What velocity criterion at the origin of the internal carotid artery is most commonly used to identify a hemodynamically significant stenosis?

  1. Peak systolic velocity greater than 125 cm/s Correct answer.
  2. Peak systolic velocity greater than 250 cm/s
  3. Peak systolic velocity greater than 50 cm/s
  4. End-diastolic velocity greater than 100 cm/s

Explanation

A peak systolic velocity exceeding 125 cm/s at the ICA origin is the standard primary threshold for a hemodynamically significant stenosis, usually combined with spectral broadening and elevated end-diastolic velocity.

Question 42Cerebrovascular testing and interpretation

Which spectral waveform feature is expected in a normal common carotid artery?

  1. Low-resistance flow with continuous forward diastolic flow
  2. Pulsatile flow with a sharp systolic upstroke and a brief diastolic reversal Correct answer.
  3. Reversed diastolic flow throughout the cardiac cycle
  4. High-resistance flow with absent diastolic flow

Explanation

The CCA supplies both the low-resistance internal carotid and the higher-resistance external carotid, so its waveform is intermediate, with a brisk systolic upstroke and a small amount of early diastolic flow reversal.

Question 43Cerebrovascular testing and interpretation

A temporal artery tap maneuver is used during carotid duplex to help distinguish which vessels?

  1. Common carotid and innominate arteries
  2. Internal and external carotid arteries Correct answer.
  3. Vertebral and basilar arteries
  4. Internal jugular and common carotid arteries

Explanation

Tapping the superficial temporal artery produces oscillations in the external carotid spectral tracing because the ECA supplies the face and scalp; the ICA tracing is unaffected.

Question 44Cerebrovascular testing and interpretation

Which finding on color Doppler most directly suggests a near-occlusive internal carotid lesion?

  1. A string sign of narrow color flow with markedly elevated velocity Correct answer.
  2. Absent color flow in the external carotid artery
  3. A wide band of color filling the entire vessel lumen
  4. Uniform color throughout the bulb with low velocity

Explanation

A near-occlusive lesion produces a very narrow residual channel, often described as a string sign, with focally very high velocities and post-stenotic turbulence.

Question 45Cerebrovascular testing and interpretation

What does an elevated resistive index in the common carotid artery most often reflect?

  1. Proximal aortic valve disease
  2. Increased distal cerebrovascular resistance Correct answer.
  3. Downstream intracranial stenosis
  4. Systemic hypotension

Explanation

The CCA resistive index rises when resistance in its distal branches increases, such as with distal ICA or intracranial disease, because the CCA waveform reflects the combined downstream beds.

Question 46Cerebrovascular testing and interpretation

Which vessel is identified by its location anterior and lateral to the internal carotid artery and by branching in the neck?

  1. External carotid artery Correct answer.
  2. Internal carotid artery
  3. Vertebral artery
  4. Internal jugular vein

Explanation

The ECA lies anterior and lateral to the ICA and typically gives off branches in the neck, such as the superior thyroid and facial arteries.

Question 47Cerebrovascular testing and interpretation

What is the normal direction of flow in the vertebral artery when imaged in the mid-cervical segment?

  1. Toward the brain during systole and reversed in diastole
  2. Away from the brain throughout the cardiac cycle
  3. Bidirectional with equal forward and reverse flow
  4. Toward the brain throughout the cardiac cycle Correct answer.

Explanation

Normal vertebral artery flow is directed cranially toward the brain throughout the cardiac cycle, with a low-resistance waveform.

Question 48Cerebrovascular testing and interpretation

Which parameter is used to calculate the percent diameter stenosis from a duplex image?

  1. Residual lumen diameter compared with the normal distal vessel diameter Correct answer.
  2. Residual lumen area compared with the vessel wall thickness
  3. Peak systolic velocity compared with the contralateral side
  4. Color pixel count within the stenosis

Explanation

Diameter stenosis is calculated by comparing the residual lumen diameter at the narrowest point with the diameter of the normal vessel, typically the distal ICA.

Question 49Cerebrovascular testing and interpretation

A patient has a peak systolic velocity of 180 cm/s at the ICA origin with an ICA/CCA ratio of 2.5. What category of stenosis does this most likely represent?

  1. Complete occlusion
  2. Normal
  3. Mild stenosis under 50%
  4. Moderate stenosis of 50-69% Correct answer.

Explanation

A PSV of 180 cm/s with a ratio of 2.5 falls in the range typically associated with 50-69% stenosis, above the significant threshold but below the very high velocity range.

Question 50Cerebrovascular testing and interpretation

Which finding suggests that a high-velocity ICA signal is due to a tandem distal lesion rather than a focal cervical stenosis?

  1. Focal color aliasing exactly at the site of highest velocity
  2. A localized plaque with post-stenotic turbulence
  3. A velocity step-up confined to a short segment
  4. Elevated velocity with a dampened distal waveform and no focal plaque Correct answer.

Explanation

Tandem distal disease can produce elevated proximal velocities without a focal plaque, and the distal waveform is dampened (tardus-parvus), helping distinguish it from a focal cervical stenosis.