Duplex/color flow imaging UE and LE

Question 1

Combination of real time B-mode imaging and Doppler spectral analysis

Answer 1

Duplex scanning

Question 2

Doppler info is displayed on image after evaluated for phase and its frequency content.

Answer 2

Doppler color flow imaging

Question 3

Sample size for acquiring pulsed doppler is usually?

Answer 3

1-1.5mm

Question 4

Uncommon for arteries in the upper extremities to become stenotic. Main use is evaluation of?

Answer 4

Dialysis access grafts

Question 5

Auscultate the access for bruit and/or palpate for a thrill (vibration). A patent ______, as well as a stenotic one can produce a thrill.

Answer 5

Dialysis access

Question 6

Evaluate dialysis access grafts as follows:

Answer 6

a) inflow artery
b) arterial anastomosis
c) continue through the body of the graft
d) observe for aneurysm, puncture sites, peri-graft fluid
e) observe color flow changes, turbulence
f) venous anastomosis
g) outflow vein

Question 7

UE dialysis access Brescia-Cimino fistula assessment sites include?

Answer 7

Inflow artery, anastomosis, and outflow vein

Straight, looped, synthetic grafts

Question 8

Normal peak systolic velocities vary widely with _____ changes. Doppler signal quality is usually triphasic.

Answer 8

Skin temperature

Question 9

If a > 50% diameter reduction is present, observe for characteristics of the?

Answer 9

Stenosis profile

post stenosis turbulence

Question 10

What aneurysms can form in response to using the palm as a hammer?

Answer 10

ulnar artery

Question 11

What aneurysms are associated with embolization to the digits?

Answer 11

Subclavian

Question 12

Peak systolic velocities and end diastolic velocities vary as to the type of access; normally both are elevated. Low PSV obtained in access graft could indicate arterial _____ problems.

Answer 12

inflow

Question 13

Most common sites for stenosis in hemodialysis access?

Answer 13

venous anastomosis and outflow vein

Question 14

Large blood volumes shunted from artery to lower resistant venous circulation, can increase venous return resulting in?

Answer 14

CHF

Question 15

In what situation is the distal arterial blood flow reversed into the lower resistant venous circulation and can cause pain on exertion, pallor and coolness of the skin distal to the shunt?

Answer 15

steal syndrome

Question 16

Doppler equation for LE duplex/color flow imaging?

Answer 16

Df= 2 Fo V Cos theta/ c
Df- doppler shift freq
Fo- carrier freq
c- speed of US through soft tissue (1540 m/s)
V- velocity of moving reflectors
Cos theta- Angle
2 represents two doppler shifts

Question 17

What do the two Doppler shifts represent in the LE doppler equation?

Answer 17

• RBC is first an observer of a stationary ultrasound field

- Then acts as a wave source when the waves scatter from its surface

Question 18

Equation for velocity

Answer 18

V= c Df/ 2 Fo Cos theta

Question 19

When solving for velocity, what increases its nonlinear influence as the angle becomes closer to 90 degrees?

Answer 19

Doppler angle theta

Question 20

If there is a > 50 % diameter reduction is suspected what should be obtained?

Answer 20

Pre-stenotic PSV
PSV in stenosis
Post-stenotic turbulence signals

Question 21

What is important to know about bypass grafts?

Answer 21

type, location, and age

Question 22

Reversed saphenous vein graft (RSVG)

Answer 22

• Small end is now prox
• Large end is distal
• Vein valves stay open due to arterial flow pressure
• Branches are ligated

Question 23

In-situ vein graft

Answer 23

• GVS stays in place
• Small end is distal
• Large end is prox
• Prior to surgery, valves broken up with special instrument, branches ligated

Question 24

Vein bypass graft evaluation includes observation of gray scale, color flow, and PSV’s of the following?

Answer 24

• Inflow artery
• Prox anastomosis
• Entire length of the vein bypass graft
• Distal anastomosis
• Outflow artery
• Also check for branches that could form AV fistulas, valves, and/or other abnormalities

Question 25

Synthetic bypass graft evaluation include observation of gray scale, color image, PSV’s of the following:

Answer 25

• inflow artery
• prox anastomosis
• mid graft
• distal anastomosis
• outflow artery

Question 26

Compare stenotic PSV to pre-stenotic PSV:

Answer 26

2:1 ratio = > 50% diameter reduction
4:1 ratio = > 75% diameter reduction
>400 cm/s PSV = 75% diameter reduction
Never accept the value of numbers alone; post-stenotic turbulence should be present

Question 27

Retrograde flow in the native artery may be evident at the distal anastomosis of a RSVG, which provides an additional source of collateral flow. Retrograde flow results from a?

Answer 27

pressure gradient

Question 28

Compare results with previous studies and observe for changes such as?

Answer 28

• Decreased of 30 cm/s in any graft segment
• Reduced PSV’s in smallest graft diameter that were greater previously
• Change from triphasic to biphasic
• Decreased in ABI of >0.15
• AV fistula