Which of the following statements is true about CW Doppler?

Continuous Wave (CW) Doppler ultrasound is unique in its operation and capabilities. One of its defining characteristics is that it does not experience aliasing limitations. Aliasing occurs in Pulsed Doppler systems when the velocity of blood flow exceeds the Nyquist limit, which is half the pulse repetition frequency. Since CW Doppler continuously emits and receives ultrasound waves, it can record high-velocity blood flow without the constraints of this limit. This allows for the measurement of very high velocities, which is particularly useful in assessing conditions such as stenosis or regurgitant flow in heart valves.

Although CW Doppler has its advantages, it is important to acknowledge its trade-offs, such as the lack of range resolution. This means it cannot determine the depth of the moving structures it is measuring. In contrast, Pulsed Doppler can localize the depth of flow but is susceptible to aliasing at higher velocities.

Thus, the statement regarding the absence of aliasing limitations highlights a critical functional aspect of CW Doppler that distinguishes it from other Doppler techniques, particularly Pulsed Doppler.