Duplex / color Flow imaging (LE) Flashcards
Calcific shadowing
Limitations
Df= 2 Fo V Cos 0
c
The Doppler equation
Df
Doppler shift
Fo
Carrier Frequency
Transducer frequency directly related to doppler frequency
V
Velocity of moving reflectors
Cos 0
Angle
c
Speed of ultrasound through soft tissue
Speed of ultrasound through soft tissue is
1540 m/sec
The number is 2 represents
two Doppler shifts (in and out)
Ideal Doppler angle for vascular exams is
60 degrees
Not reliable Doppler angle is
> 60 degrees
For native arteries you scan with what type of probe
7 - 5 MHz frequency linear array
If a > 50% diameter reduction is suspected obtain
Pre- stenotic PSV
PSV (highest) in stenosis
GSV - taken out
Small end is now Proximal
Large end is distal
Vein valves stay open due to arterial flow pressure
Branches are ligated (tributraies are cut off)
Reversed saphenous vein graft (RSVG)
GSV stays in place
Small end is distal ‘
Large end is proximal
Prior to surgery, valves broken up with special instrument; branches ligated
In - situ Vein graft