ARDMS SPI Color Doppler and Artifacts 4

Question 1

The Nyquist limit for color Doppler is defined as:

Accepted Answer

Half the pulse repetition frequency

Answer

The Nyquist limit equals PRF/2; velocities producing Doppler shifts above this threshold will alias and wrap to the opposite color.

Question 2

Color priority threshold in color Doppler determines:

Accepted Answer

Which pixels display color versus grayscale based on echo amplitude

Answer

Color priority sets the brightness level above which grayscale tissue signal overrides color, preventing color from painting solid structures.

Question 3

Spectral broadening on a color Doppler-guided pulsed wave trace at a stenosis is caused by:

Accepted Answer

A wide range of velocities from turbulent flow filling the spectral window

Answer

Turbulent flow post-stenosis contains a broad distribution of velocities that fill the spectral window, producing spectral broadening.

Question 4

Which artifact can make a non-vascular structure such as a simple cyst appear to contain color Doppler signal?

Accepted Answer

Color bleed (blooming)

Answer

Excessive color gain (blooming) can cause color signal to spill into adjacent avascular structures such as simple cysts.

Question 5

In color Doppler, increasing the color box angle (steering) away from perpendicular to the vessel:

Accepted Answer

Improves Doppler angle and increases color sensitivity

Answer

Steering the color box to achieve a smaller insonation angle increases the cosine factor, producing larger frequency shifts and better color filling.

ARDMS SPI - ARDMS Sonography Principles and Instrumentation Practice Test