7. Advanced Ultrasound Modes (Doppler)

Continuous Wave (CW) Doppler Mode

Continuous Wave Doppler is very similar to pulse wave Doppler except it does not alias and can detect very high velocities (greater than 1000cm/second). So Continuous Wave Doppler is the optimal choice for measuring high-velocity applications such as valvular stenosis and regurgitation.

Unlike Pulse Wave Doppler which has a sampling gate to measure a single point along your cursor, Continuous Wave Doppler measures all points along your cursor. Therefore what you will see will be the maximum velocity of flow detected along the cursor line. This is a pro and a con. It is a pro because you don’t have aliasing and can detect high velocities, but it is a con because you don’t know exactly where that velocity is coming from on the cursor. Also if there are two velocities along the cursor line, you won’t be able to differentiate the lower velocity compared to the higher velocity signal, since the high-velocity signal will mask the low-velocity one.

The steps to performing continuous wave Doppler are the similar to Pulse wave Doppler except where you put the sample gate does not matter. It will measure velocities across the entire cursor line.

Steps to performing Continuous Wave Doppler:

  • CW Doppler Step 1: Push Continuous Wave Doppler Button to make CW Cursor line appear
  • CW Doppler Step 2: Place CW Cursor at Area of Interest (where you put the sample gate doesn’t matter)
  • CW Doppler Step 3: Push CW button again to activate Continuous Wave Doppler Mode
  • CW Doppler Step 4: Adjust the CW Gain, Baseline, and Scale
  • CW Doppler Step 7: Adjust the Sweep Speed (if needed)
  • CW Doppler Step 8: Push the Freeze Button
  • CW Doppler Step 9: Scroll to the desired image
  • CW Doppler Step 10: Push Measure Button
  • CW Doppler Step 11: Measure Area of Interest

Here is an example of measuring tricuspid regurgitation (TR) using continuous wave Doppler. Notice how CW Doppler can measure the high velocity of this TR jet (344cm/s).

Tricuspid Regurgitation - Continuous Wave Doppler
Tricuspid Regurgitation – Continuous Wave Doppler

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