Chapter 12: Duplex/Color imaging of LE

Question 1

what information does LE duplex provide

Answer 1

asses >50% diameter reduction
occlusions
anerusyms
f/u bypass grafts
localize stenotic lesion prior to balloon angioplasty

Question 2

the doppler equation:

Answer 2

Df = 2FoVCos0 / C

Question 3

Df =

Answer 3

Doppler shift frequency

Question 4

Fo =

Answer 4

transduce frequency

Question 5

c =

Answer 5

speed of sound through soft tissue (1540 m/sec)

Question 6

V =

Answer 6

velocity of moving reflectors

Question 7

Cos 0 =

Answer 7

angle

Question 8

the number 2 represents

Answer 8

2 dopper shifts

Question 9

calculating velocity equation

Answer 9

V= C Df / 2FO cos 0

Question 10

source of error for calculating velocity

Answer 10

doppler angle theta which increases its nonlinear influence as angle becomes closer to 90 degrees

Question 11

LE arterial scan includes duplex of

Answer 11

dst external iliac art
CFA
CFA bifurcation 
SFA prox to distal
POP art prox to dist
Ant Tib art
Post tib art
peroneal art

Question 12

if greater than 50% diameter reduction is suspected, obtain:

Answer 12

Pre stenotic PSV
PSV at stenosis
Post Stenosis turbulence signals

Question 13

Reversed Saphenous Vein Graft (RSVG)

Answer 13

small end now proximal
large end distal
vein valves stay open due to arterial flow pressure
branches are ligated

Question 14

In- Situ Vein Graft

Answer 14

GSV stays in place
small end distal
large end proximal
prior to surgery valves broke up with special instrument
branches ligated

Question 15

assessment of bypass graft includes

Answer 15

ABIs

Question 16

Vein bypass graft evaluation:

Answer 16

gray, color and PSV of
inflow artery
prox anatomosis
entire length of graft
distal anast
outflow artery
check for branches that could form AV fistulas

Question 17

synthetic bypass graft evaluation:

Answer 17

gray,color,PSV of
inflow artery
prox anast
mid graft
dist anast
outflow artery

Question 18

Normal native LE doppler

Answer 18

triphasic but can be biphasic in some patients

Question 19

Abnormal native artery findings

Answer 19

compare stenosis PSV to pre stenotic PSV

Question 20

stenotic PSV to prestenotic PSV 2:1 ratio

Answer 20

> /= 50% diameter reduction

Question 21

stenotic PSV to prestenotic PSV 4:1 ratio

Answer 21

> / = 75% diameter reduction

Question 22

> 400 cm/sec PSV

Answer 22

> / = 75% diameter reduction

Question 23

Normal findings of Bypass graft doppler

Answer 23

low resistance flow

some retrograde flow in native artery at distal anastomosis of RSVG

Question 24

Abnormal findings of bypass graft doppler

Answer 24

compare to prior studies and look for changes like:
decrease of 30cmsec anywhere in graft
reduced PSV
change from triphasic to biphasic 
decrease in ABI >.15
AV fistulas

Question 25

In general stented artery PSV is usually

Answer 25

elevated slightly

greatly elevated suggest stenosis