Which of the following is NOT a type of Doppler imaging? pulse-wave  color  2nd harmonics spectral  continous-wave

To determine which option is NOT a type of Doppler imaging, let's briefly describe each option:

1. Pulse-wave Doppler: This technique uses a series of pulses to measure blood flow velocities. It is widely used in echocardiography and vascular imaging.

2. Color Doppler: This imaging technique displays blood flow information in color superimposed on a greyscale image, making it easier to visualize the direction and speed of blood flow.

3. 2nd Harmonics: This refers to imaging techniques that utilize the second harmonic frequency of an ultrasound wave. It is not a Doppler imaging technique but rather an imaging enhancement technique.

4. Spectral Doppler: This method provides a graph of blood flow velocity over time, indicating the characteristics of blood flow.

5. Continuous-wave Doppler: This technique uses continuous ultrasound waves to measure high-velocity blood flow.

Final Answer

The option that is NOT a type of Doppler imaging is 2nd harmonics.