RVT Hemodynamics and Doppler Principles 5

Question 1

What is the primary cause of the 'to-and-fro' waveform pattern seen in a pseudoaneurysm neck on duplex ultrasound?

Accepted Answer

Bidirectional flow as blood enters during systole and exits during diastole

Answer

Arteriovenous shunting within the pseudoaneurysm

Answer

Turbulent flow from thrombus within the sac

Answer

Reversed flow from proximal arterial occlusion

Question 2

A tardus-parvus waveform pattern distal to an arterial obstruction is characterized by:

Accepted Answer

Delayed, rounded systolic peak with reduced amplitude and loss of diastolic reversal

Answer

Rapid systolic upstroke and high peak velocity

Answer

Triphasic waveform with increased peak systolic velocity

Answer

Absent diastolic flow with normal systolic velocity

Question 3

In renal artery duplex assessment, which indirect parameter best reflects significant proximal renal artery stenosis when direct visualization is limited?

Accepted Answer

Renal acceleration time and acceleration index

Answer

Renal cortex thickness

Answer

Renal volume index

Answer

Peak systolic velocity in the arcuate arteries

Question 4

Which parameter is used to calculate volume flow rate (mL/min) when performing duplex assessment of a dialysis access?

Accepted Answer

Time-averaged mean velocity and vessel cross-sectional area

Answer

Peak systolic velocity and resistivity index

Answer

End-diastolic velocity and pulsatility index

Answer

Acceleration time and vessel diameter

Question 5

Harmonic imaging in vascular ultrasound primarily reduces which artifact?

Accepted Answer

Near-field clutter and side-lobe artifacts

Answer

Shadowing from calcified plaque

Answer

Color Doppler aliasing

Answer

Spectral broadening from angle errors

Question 6

An arteriovenous fistula (AVF) feeding artery typically demonstrates which hemodynamic pattern compared to the contralateral normal artery?

Accepted Answer

Lower resistance with increased diastolic flow and elevated peak systolic velocity

Answer

Higher resistance with absent diastolic flow

Answer

Normal triphasic waveform with equivalent peak velocity

Answer

Reversed diastolic flow indicating steal phenomenon

Question 7

When evaluating the vertebral arteries, complete subclavian steal physiology on the symptomatic side is confirmed when Doppler shows:

Accepted Answer

Complete reversal of flow direction throughout the entire cardiac cycle

Answer

Normal antegrade flow throughout the cardiac cycle

Answer

Antegrade systolic flow with retrograde diastolic flow only

Answer

Absence of detectable flow signal