ARDMS SPI Spectral Doppler Waveform Analysis 3

Question 1

Increasing the sample volume (gate) size in spectral Doppler will most likely:

Accepted Answer

Include more of the vessel lumen and potentially increase spectral broadening

Answer

A larger sample volume captures flow across more of the vessel cross-section, including slower cells near the vessel walls, which introduces a wider range of velocities and increases spectral broadening.

Question 2

The systolic-to-diastolic (S/D) ratio used in obstetric Doppler is calculated as:

Accepted Answer

PSV / EDV

Answer

The S/D ratio = PSV / EDV and is commonly used in umbilical artery Doppler to assess placental resistance; it cannot be calculated when EDV is absent.

Question 3

When PRF is increased to correct aliasing, which undesirable consequence may occur?

Accepted Answer

Range ambiguity — inability to unambiguously sample deep vessels

Answer

High PRF sends pulses before previous echoes return from deep structures, so the system cannot determine which echo came from which pulse depth, creating range ambiguity artifact.

Question 4

Baseline shifting in spectral Doppler is primarily used to:

Accepted Answer

Reposition the zero-velocity line to allocate more display range to unidirectional flow

Answer

Shifting the baseline moves the zero-velocity reference line, allowing more of the display to be used for flow in one direction before aliasing wraps the signal to the other side.

Question 5

Compared to pulsed-wave (PW) Doppler, which statement about continuous-wave (CW) Doppler is TRUE?

Accepted Answer

CW has no Nyquist limit and can measure very high velocities without aliasing

Answer

CW Doppler continuously transmits and receives simultaneously; because it does not use pulsed sampling, it has no PRF and therefore no Nyquist limit, allowing measurement of very high velocities — at the cost of range discrimination.

ARDMS SPI - ARDMS Sonography Principles and Instrumentation Practice Test

ARDMS SPI - ARDMS Sonography Principles and Instrumentation Practice Test

ARDMS SPI Spectral Doppler Waveform Analysis 3