In Doppler ultrasound, what effect does increasing the Doppler scale have?

Increasing the Doppler scale in ultrasound enhances the maximum detectable velocity. The Doppler scale determines how the frequency shifts, which are used to calculate blood flow velocities. When the scale is increased, the Nyquist limit also increases, enabling the detection of higher blood flow velocities without the risk of aliasing. This means that if the velocity of blood flow exceeds the limits of the Doppler scale, it would lead to inaccurate readings known as aliasing, where the higher velocities appear to be going in the opposite direction. Thus, by adjusting the Doppler scale, you can effectively capture a broader range of velocities in the imaged vessel.

The other options do not hold true in this context. For example, increasing the Doppler scale does not decrease the Nyquist limit; rather, it increases it. While increasing the scale may help manage some artifacts, it does not eliminate them entirely. Also, adjusting the Doppler scale does not impact the frequency of the transmitted signal directly; it relates to how the frequency shifts are interpreted in relation to blood flow velocities.