How can aliasing artifact in ultrasound imaging be corrected?

Aliasing artifact in ultrasound imaging occurs when the sample rate is insufficient to accurately represent the frequency of a signal, particularly in cases of high-velocity blood flow. This results in a misrepresentation of flow direction and speed. Increasing the Pulse Repetition Frequency (PRF) raises the rate at which pulses are emitted, allowing for more frequent sampling of the signals returning from the tissue and blood flow.

When the PRF is increased, the Nyquist limit—the maximum frequency that can be accurately measured without aliasing—also increases. This helps to capture higher-velocity flows without distortion, effectively correcting the aliasing artifact. It is crucial that the PRF is set appropriately according to the expected flow velocities in order to avoid the occurrence of aliasing in the first place.

In contrast, decreasing the PRF would lower the Nyquist limit, making aliasing more likely to occur. Changing the transducer frequency or adjusting the imaging depth can also influence aliasing but do not directly resolve the issue as effectively as an appropriate increase in the PRF does.