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

Impedance mismatch at the blood-vessel wall interface

Answer

Increased attenuation of sound by erythrocytes

Answer

Refraction of the sound beam by flowing blood

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

0 degrees (parallel)

Answer

45 degrees

Answer

60 degrees

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

Complete vessel occlusion

Answer

Normal vessel anatomy

Answer

Arteriovenous fistula distal to the site

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

Normal laminar flow

Answer

Increased flow volume

Answer

A low-resistance organ bed

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

Pressure is constant throughout the circulation

Answer

Resistance is equal in all vessel segments

Answer

Viscosity determines velocity distribution

Question 6

A post-stenotic waveform showing low PSV, slow systolic acceleration time, and absence of the early diastolic reversal component is described as:

Accepted Answer

Tardus-parvus

Answer

High-resistance triphasic

Answer

Hyperemic monophasic

Answer

Normal biphasic