ARDMS SPI Hemodynamics and Vascular Flow Principles 3

Question 1

What is the primary acoustic effect that enables Doppler ultrasound to detect moving blood cells?

Accepted Answer

The Doppler effect: frequency shift in echoes from moving reflectors

Answer

Moving red blood cells shift the frequency of the returning echo relative to the transmitted frequency; this Doppler frequency shift is proportional to velocity.

Question 2

The Doppler equation shows that detected frequency shift is zero when the angle between the beam and flow direction is:

Accepted Answer

90 degrees (perpendicular)

Answer

At 90 degrees, the cosine of the angle equals zero, making the Doppler frequency shift zero regardless of actual velocity; Doppler is therefore unusable at this angle.

Question 3

Which clinical finding is associated with markedly increased peak systolic velocity (PSV) at a focal arterial segment?

Accepted Answer

Focal arterial stenosis with hemodynamic significance

Answer

Flow accelerates as it passes through a stenotic segment due to reduced cross-sectional area, causing a focal jet with markedly elevated PSV.

Question 4

Spectral broadening without a visible spectral window in a peripheral artery most likely indicates:

Accepted Answer

Post-stenotic turbulence or intrinsic vessel disease

Answer

Turbulence downstream of a stenosis produces cells moving at many different velocities simultaneously, filling the spectral window and causing broadening.

Question 5

The continuity equation in hemodynamics states that flow rate is conserved, meaning:

Accepted Answer

Cross-sectional area × velocity is constant at any point along a vessel

Answer

The continuity equation (Q = A × V) states that volumetric flow rate equals cross-sectional area times velocity and is conserved, so a smaller area requires higher velocity.

ARDMS SPI - ARDMS Sonography Principles and Instrumentation Practice Test

ARDMS SPI - ARDMS Sonography Principles and Instrumentation Practice Test

ARDMS SPI Hemodynamics and Vascular Flow Principles 3