NOTE: Pulsed-Wave Doppler is available in the Vascular: Access, Vascular: Carotid presets to Pro, Pro Team, and Enterprise customers using either iQ or iQ+ in the United States and iQ+ users in Canada. Pulsed Wave Doppler is also available in the Cardiac and Cardiac Coherence presets to iQ+ users in the United States.
Spectral Pulsed-Wave Doppler is a quantitative mode that graphically displays blood flow velocity measurements over time. When using Pulsed Doppler, you can:
- View and adjust the position of the sample volume by holding and dragging the gate.
- View and adjust the angle correction by holding and dragging the white caliper dot.
- Switch between live Pulsed Doppler mode and live B-mode by touching the Start Spectrum/Update B-mode button.
- Adjust the gain of the spectral trace by dragging your finger left and right on the trace while the trace is live.
- Adjust the Scale to optimize for high or low flow by touching the Low Flow/High Flow control in the middle of the screen. Note that the control defines your current state.
- Adjust the Scroll Speed of the Spectral Doppler trace by touching the Slow Scroll/Fast Scroll control in the middle of the screen. Note that the control defines your current state.
In order to adjust the Gain and Depth of the B-mode reference image, exit Pulsed Doppler mode and optimize the image in B-mode, Color Doppler mode, or Power Doppler mode.
To use Spectral Pulsed-Wave Doppler:
- Select the Vascular: Access or Vascular: Carotid preset.
- Select the Actions button at the bottom of the screen. Select Pulsed Doppler.
- Hold and drag the sample volume gate (the square region in the center of the arrow) to the desired location within the vessel of interest.
- Once positioned, align the direction of the arrow along the direction of flow. If the flow in the vessel is cranial, point the arrow cranially. If the flow in the vessel is caudal, point the arrow caudally.
- Caution: Flow directionality is represented relative to the direction of the arrow. Misalignment of the arrow may lead to misinterpretation of flow direction. Carefully check that the arrow is aligned with the expected blood flow direction.
- Note: Flow in the direction of the arrow will always be depicted above the baseline. Flow against the direction of the arrow will always be depicted below the baseline.
- Tap “Start Spectrum” to start the spectral trace.
- If you do not see a trace, adjust the position of the sample volume. To adjust the position of the sample volume:
- Hold and drag the arrow, which will automatically pause the spectrum and restart the B-mode reference image.
- Tap the Update B-mode button to manually pause the spectrum and restart B-mode.
- To adjust the scroll speed of trace, tap the “Slow Scroll/Fast Scroll” button.
- To adjust the velocity scale, tap the button Low Flow/High Flow button or drag baseline.
- To add annotations, freeze the image and tap the annotations button.
- To add measurements, freeze the image and select linear measurements.
- Note: Annotations and measurements may only be added to the Spectral trace region.
- Velocity measurements will be represented in cm/s as Peak Systolic Velocity (PSV), the absolute value of the vertical distance from the baseline first caliper dot, and End Diastolic Velocity (EDV), the absolute value of the vertical distance from the baseline of the second caliper dot.
- The difference in time between the left and right ends of the caliper will be represented as time (t) in seconds.
- To save a Pulsed Doppler image, freeze then press the capture button.
Using Spectral Pulsed-Wave Doppler in Cardiac presets:
For Cardiac presets the pulsed wave doppler mode has the following differences geared towards Cardiac applications:
- There is no angle correction.
- There is no inversion.
- Similar to Fetal Heart Sounds, to move the Sample Volume, the user can hold on the blue dot. Note: holding in the general vicinity of the blue dot will move the gate as well.
- Because the measurements on the Spectrum could be used for any of the peaks, the velocities are generic: v1 and v2.
- Following the convention used in Cardiac Pulsed Wave Doppler, only the absolute value of the measured velocities is shown.