Podcast
Questions and Answers
In which situation does aliasing occur when observing Doppler shifts?
In which situation does aliasing occur when observing Doppler shifts?
- When PRF is set too low (correct)
- When the linear flow is moving at moderate speed
- When the Doppler gain is maximized
- When the PRF is set too high
What is the primary method to remove the effects of low amplitude Doppler shifts?
What is the primary method to remove the effects of low amplitude Doppler shifts?
- Implementing a wall filter (correct)
- Adjusting the baseline
- Increasing the PRF
- Using the Doppler gain
How is the relationship between Doppler angle and Doppler shift characterized?
How is the relationship between Doppler angle and Doppler shift characterized?
- Direct relationship
- Inversely proportional relationship (correct)
- Exponential relationship
- Linear relationship
What can result when the Doppler shift exceeds the Nyquist Limit?
What can result when the Doppler shift exceeds the Nyquist Limit?
What is the Nyquist Limit defined as in relation to the PRF?
What is the Nyquist Limit defined as in relation to the PRF?
Study Notes
Aliasing
- Aliasing occurs in two situations:
- When linear flow is moving very fast
- When PRF is set too low
- Aliasing can be corrected in four ways:
- Adjust the scale
- Doppler shift (closer to baseline)
- Adjust the baseline
- Switch to CW
- No Doppler shift is displayed in black
- Doppler Gain is a utility controlled by the vis operator that can amplify the amplitude of Doppler shifts, increasing their brightness on the screen.
- The relationship between Doppler Angle & Doppler Shift is inverse.
- The maximum value of the “scale” is the Nyquist Limit.
- A Wall Filter is a filter used to reject or delete low amplitude Doppler shifts.
- The Nyquist Limit is -1/2 the PRF.
- Aliasing is the most common artifact encountered when using Doppler
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Description
This quiz explores the concepts of aliasing in Doppler ultrasound, including how it occurs and methods of correction. Test your understanding of the relationship between Doppler angle, scale, and Doppler shift, as well as the implications of the Nyquist Limit and Wall Filter.
