*Doppler & Hemodynamics Flashcards
Pulsitility index
Peak systole - end diastole / mean velocity
What will resolve aliasing (5)
Decrease baseline Increase < Decrease operating frequency Increase PRF Decrease depth
Doppler shift equation
When will it be a positive shift?
Fd = Fr-Ft
Received frequency is greater than the transmitted frequency
What would increase the systems sensitivity of the doppler shifts?
Increasing operating frequency
The speed at which blood travels through a vessel is more likely dependent on which
- volume flow rate
- size of capillaries
- left ventricular output
- resistance of the venules
Left ventricular output
The greatest portion of circulating blood is located in the
Venous system
Noise vs motion artifacts in doppler
Noise = clutter Motion = flash
The size of the sample volume is determined by (3)
Beam diameter
SPL
Receiver gate length
In colour-flow Doppler, multiple sample gates positioned in the ROI is
Packets
How to fix flash artifact?
Decrease colour gain
If you see a spectral doppler waveform where there is a distinct line cutting off slow flows, what would you do?
Decrease wall filter
What type of flow do smaller arteries show?
Laminar
