Chapter 12 Duplex/ Color Flow Imaging Lower Extremity

Question 1

What is the Doppler equation

Answer 1

Df= 2 Fo V Cos 0 / C

Question 2

What is the speed of ultrasound through soft tissue

Answer 2

1540 m/sec

Question 3

What is the ideal Doppler angle for vascular exams

Answer 3

60 degrees center stream parallel to walls

Question 4

If the transducer frequency is decreased what happens to the Doppler waveform size

Answer 4

Decreases

Question 5

What type of transducer should be used

Answer 5

7 or 5 MHz linear array

Question 6

If a 50% diameter reduction is suspected you obtain what 2 things

Answer 6

1) pre stenotic PSV
2) PSV highest in stenosis

Question 7

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

Answer 7

Reversed saphenous vein graft

Question 8

If the GSV stays in place, small end is distal, large end is proximal this is a sign of

Answer 8

In Situ vein graft

Question 9

A 2:1 ratio is what percentage of diameter reduction

Answer 9

> 50%

Question 10

A 4:1 ratio of what percentage is diameter reduction

Answer 10

> 75%

Question 11

If it’s greater than 400 cm/sec PSV what is the diameter reduction

Answer 11

> 75%

Question 12

Retrograde flow in a bypass graft results from a

Answer 12

Pressure gradient