Chapter 12 Duplex/ Color Flow Imaging Lower Extremity Flashcards
What is the Doppler equation
Df= 2 Fo V Cos 0 / C
What is the speed of ultrasound through soft tissue
1540 m/sec
What is the ideal Doppler angle for vascular exams
60 degrees center stream parallel to walls
If the transducer frequency is decreased what happens to the Doppler waveform size
Decreases
What type of transducer should be used
7 or 5 MHz linear array
If a 50% diameter reduction is suspected you obtain what 2 things
1) pre stenotic PSV
2) PSV highest in stenosis
If the small end is now prox, large end is distal, vein valves stay open due to arterial flow pressure and branches are ligated this is a sign of
Reversed saphenous vein graft
If the GSV stays in place, small end is distal, large end is proximal this is a sign of
In Situ vein graft
A 2:1 ratio is what percentage of diameter reduction
> 50%
A 4:1 ratio of what percentage is diameter reduction
> 75%
If it’s greater than 400 cm/sec PSV what is the diameter reduction
> 75%
Retrograde flow in a bypass graft results from a
Pressure gradient