Doppler Artifacts Flashcards
What is frequency aliasing?
occurs when a signal is sampled at a rate that is insufficient to capture the changes in the signal accurately. This typically happens when the sampling rate is below the Nyquist rate, which is twice the highest frequency present in the signal.
Describe Intrinsic Spectral broadening artifact
occurs when there is turbulence in blood flow, causing the normally uniform velocity of red blood cells to vary. This variation results in a broadening of the spectral Doppler waveform, which appears as a fill-in of the area between the waveform and the baseline
What is doppler spectral mirror artefact
occurs when the Doppler ultrasound signal is reflected symmetrically on both sides of the baseline, creating a mirror image
Describe Wall thump artefact in doppler imaging
occurs when the motion of the arterial wall creates a low-frequency signal that can interfere with the spectral Doppler waveform of blood flow - appears as an audible and visible “thump” on the ultrasound display
What is Doppler motion artifact?
occurs when there is movement during the acquisition of Doppler ultrasound images. This can be due to patient movement, breathing, or even the motion of the ultrasound probe itself.
Describe Twinkle artefact in doppler ultrasound
a rapidly alternating pattern of red and blue colors appears behind a highly reflective object, such as a kidney stone or calcification. This artifact mimics turbulent blood flow and is more pronounced with rough surfaces
What is colour signal dropout in doppler ultrasound?
occurs when the color flow signal is lost or not displayed in certain areas where blood flow is expected
Describe colour bleeding in doppler ultrasound
an artifact where the color flow signal extends beyond the actual boundaries of the blood vessel, making it appear as though the flow is spreading into adjacent tissues.
What is Flash artefact in doppler imaging?
a motion artifact that appears as a sudden burst of color filling the color Doppler box, often obscuring the grayscale image. This artifact is typically caused by movement of the patient or the ultrasound transducer
How can we minimize frequency aliasing
Increase the Pulse Repetition Frequency (PRF)
Adjust the Baseline
Use a Lower Frequency Transducer
Optimize the Doppler Angle
Choose a Shallower Sample Volume
How can we minimize Intrinsic Spectral broadening artifact?
Optimize Doppler Angle
Adjust Sample Volume Size
Increase Pulse Repetition Frequency (PRF
Proper Gain Settings
How can we minimize spectral mirror artefact?
Adjust Gain Settings
Optimize Insonation Angle
Apply Wall Filters
Change Scanning Position
