What is the area underneath the systolic peak on a Doppler waveform that is devoid of echoes called?

What is the area underneath the systolic peak on a Doppler waveform that is devoid of echoes called?

• A. Spectral window
• B. Spectral broadening
• C. Velocity aliasing
• D. Flow reversal

Answer: (A)

In a Doppler spectrum, the velocities that are actually present in the blood flow appear as echoes forming a trace. The area beneath the systolic envelope that has no echoes is called the spectral window. It’s a gap in the spectrum where no backscattered signal is detected at those velocities, a normal feature arising from how the signal is sampled and filtered. This isn’t due to broadening from multiple velocities, nor to aliasing of high velocities, nor to flow in the opposite direction; those phenomena produce different patterns in the spectrum.

In a Doppler spectrum, the velocities that are actually present in the blood flow appear as echoes forming a trace. The area beneath the systolic envelope that has no echoes is called the spectral window. It’s a gap in the spectrum where no backscattered signal is detected at those velocities, a normal feature arising from how the signal is sampled and filtered. This isn’t due to broadening from multiple velocities, nor to aliasing of high velocities, nor to flow in the opposite direction; those phenomena produce different patterns in the spectrum.