Duplex / Color Flow Imaging (LE) Flashcards
1
Q
Capabilities of duplex / color flow imaging in LE?
A
- determine presence/absence of >50% diameter reduction or occlusion
- determine presence/absence of aneurysm
- follow up of bypass grafts
- to localize the stenotic lesion prior to balloon angioplasty
2
Q
Limitations of duplex / color flow imaging in LE?
A
- dressings, staples, sutures, open wounds
- incisional tenderness, hematomas
- obesity
- calcific shadowing from diabetes and/or atherosclerosis
3
Q
Patient positioning with duplex / color flow imaging in LE?
A
- supine with head on pillow
- close to examiner
- patients hip minimally rotated externally, with knee flexed
- prone or lateral decubitus position may be required for assessment of popliteal arteries
4
Q
What is the doppler equation?
A
Df = 2 Fo V Cos 0 / c
5
Q
What does Df stand for?
Df = 2 Fo V Cos 0 / c
A
Df - Doppler shifts frequency
6
Q
What does Fo stand for?
Df = 2 Fo V Cos 0 / c
A
Fo - Carrier frequency
7
Q
What does c stand for?
Df = 2 Fo V Cos 0 / c
A
c - Speed of ultrasound through tissue
(1540 m/sec)
8
Q
What does V stand for?
Df = 2 Fo V Cos 0 / c
A
V - Velocity of the moving reflectors
** is a calculation
9
Q
What does Cos 0 stand for?
Df = 2 Fo V Cos 0 / c
A
Cos 0 - Angle
