Doppler Artifacts

Question 1

Which imaging artifacts are also relevant to Doppler

Answer 1

Shadowing
Mirror image
Reverberation
Refraction
Range ambiguity

Question 2

Describe frequency aliasing
How can it be addressed?

Answer 2

Occurs when Doppler shift exceeds PRF/2 (Nyquist limit)

If not severe, shift baseline up or down
If severe, increase Doppler PRF (limited due to range ambiguity)
Reducing frequency also reduces aliasing as Doppler shift is proportional to the ultrasound frequency

Question 3

Intrinsic spectral broadening

Answer 3

Beam assesses Doppler shift from a number of angles, rather than just the ideal, assumed angle

Question 4

Spectral mirror artifact

Answer 4

Doppler spectrum is symmetrical above and below the baseline
Generally due to intrinsic spectral broadening, when beam is perpendicular to the flow direction

Question 5

Twinkling artifact

Answer 5

Random fluctuating colour Doppler signals seen in the presence of stones and similar objects