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Vascular Lab > RPVI-Cerebrovascular > Flashcards

RPVI-Cerebrovascular Flashcards

1
Q

what is the accuracy of carotid US?

A

> 95%

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2
Q

what linear transducer should be used for carotid?

A

5-12MHz

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3
Q

what are indications for carotid sonography?

A 
TIA
resolving ischemic neuro deficit
CVA
bruits
F/U 
post-op
suspected dissection
signif RF
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4
Q

what are signs of anterior circulation accidents?

A 
paresis, parathesia, paralysis unilateral 
aphasia
dysphasia
dysphagia
amaurosis fugax
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5
Q

what are signs of posterior circulation accidents?

A 
vertbral or posterior cerebral
bilateral vision problems
diploplia
drop attack (fall with  no LOC)
vertigo
ataxia
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6
Q

what are non-localizing symptoms?

A

dizzy lightheadedness
syncopy
H/A
confusion

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7
Q

what are some anatomic variation of carotid anatomy?

A 
L CCA can come of innominant 10%
common origin innominate and LCCA 12%
l vert of arch 3%
r CCA off arch rare
R sub off arch distal to L sub rare
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8
Q

at which level does vert enter brain?

A

C6

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9
Q

how many branches of ECA?

A 
8
we can see the following*
sup thyroid*
asc pharyngeal
lingual
facial*
occipital *
post auricular
temporal*
maxillary
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10
Q

what are collateral pathways?

A

circle of willis-anterior communicating

opthalmic-facial

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11
Q

how do we tell arteries from veins?

A

artery wall usually thicker
shape-vein elongate usually because of scanning pressure
flow direction
compressibility
position-vein ant above umbilicus usually

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12
Q

what does red signify?

A

red away transducer

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13
Q

where is the bifurcation usually?

A

65% at c4
above c4 17%
below c4 18%

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14
Q

what is the position go ICA to ECA

A

usually posterolateral 50%

too may exceptions though

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15
Q

how to distinguish ICA fro ECA

A 
int jug vein usually follows ICA
ICA>ECA
ICA usually posterolateral
ICA no branches in neck ECA does
temporal tap
ICA is low resistance, ECA high resistance
ECA is usually medial and anterior
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16
Q

what anatomy should be imaged in 2d or colour

A

CCA, bulb, bifurcation, ECA, ICA, SCA

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17
Q

when should you freeze the colour image?

A

systole

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18
Q

how should the sample angle be positioned?

A

parallel to arterial wall

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19
Q

if 60 not possible what angle should you use?

A

lower angle

higher has more error

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20
Q

what are normal hemodynamics in CCA

A 
laminar flow
shape peak
brisk acceleration
open spectral window
forward flow
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21
Q

what is normal flow in the bulb?

A

flow separation
low resistance
loss of spectral window-turbulence
bidirectional flow

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22
Q

normal flow in ICA

A

laminar flow
low resistance
forward flow

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23
Q

normal flow in ECA?

A 
laminar flow
high resistance
minimal diastolic flow
pulsatile
dicrotic notch
24
Q

normal vertebral flow

A

laminar
low resistance
forward flow
looks like CCA

25
Q

when should you look at subclavian

A

> 20 mmhg BP difference

abnormal flow in vert

26
Q

What do you do if no colour?

A

inrease gain, lower PRF, change filter, check angle, check with pulse doppler

27
Q

what do you do if lots of colour noise?

A

decrease gain, increase PRF, use higher filter, check baseline

28
Q

where do you sample the ICA?

where do you sample CCA?

A

3 cm from bifurcation

1-2 sample from bifurcation

29
Q

what is normal intimal thickness?

A

1.2mm

30
Q

what features do we describe plaque by?

A

location extent severity

appearance

31
Q

what does high echogenicity of plaque signify?

A 
higher content of calcification
hypo likely fat content
low echo--fatty
medium
high--calcified
32
Q

how do we classify plaque PS?

A

Plaque
P1 homogeneous
P2 hetero

remember specular reflector will have brighter surface

surface
S1 smooth
S2 irregular 2mm

33
Q

what is the SRU criteria for a normal ICA?

A

PSV <125
Esv <40
Ratio <2
no plaque

34
Q

what is the SRU criteria for <50%

A

same as normal but <50% diameter reduction of plaque

35
Q

what is the SRU criteria for 50-69%

A

PSV 125-230
ratio 2-4
ICA EDV 40-100
>50% diameter reduction

36
Q

what is the SRU criteria >70-99%

A

PSV >230 cm/s low if near occlusion
ICA/CCA PSV ratio >4
ICA EDV >100 cm/s

37
Q

what is the SRU criteria occlusion

A

PSV, Ratio, EDV not useful

38
Q

where do you place the doppler gate in a high grade stenosis?

A

area of highest aliasing

can open gate

39
Q

what can indicate downstream stenosis?

A

decrease diastolic flow

40
Q

what does the image at a stenosis look like?

A

elevated v
spectral bradening
audible high pitch

41
Q

what about image distal to stenosis

A

slow systolic–dampened
rounded systolic peak
increased diastolic flow
turbulent flow

42
Q

what happens to flow velocity as stenosis goes up?

A

it increases until about 95% then it rapidly decrease and is at zero at 100%

43
Q

what are primary effects of stenosis?

A

increased PSV and EDV

44
Q

what are secondary effects of stenosis?

A

downstream turbulence
parvus tardus
higher pulsatily index upstream
lower pulsatility downstream

45
Q

What are tertiary effects of stenosis?

A

compensatory flow
collateral flow
reversed vertebral flow due to subclavian stenosis

46
Q

what are exceptions to grading criteria?

A

long stenosis

tandem stenosis

47
Q

what sources of error can cause misinterpretation?

A

CHF
arrhtymias
irregular HB
evident bilateral

HTN-effect pulsatility
diminished arterial compliance
resp motion-changes doppler angle

AS
compensatory flow on contra side

48
Q

What happens with compensatory flow?

A

side contra to stenosis has compensatory flow through collateral systems and therefor velocities may meet criteria when there is not plaque present

49
Q

what effects outflow of the ICA

A

distal ica occlusion
mca occlusion
distal disection aneurysm, avm
distal near occlusion of ICA or MCA–increased PI at prix sites
distal avm result in lower PI at prix sites

50
Q

how do we tell if era is imp collateral?

A

reversed flow in ECA to ipsi ICA
contr/ipsi ECA to circle through opthalmic
subclavian to infer thyroidal to sup thyroidal

51
Q

what are common errors in imaging

A

careless angle correct adjustment–can lead to great error 5 degrees = 15%error
inappropriate steering of the colour box
color or pulsed doppler gain too high or too low
bad adjustment of colour scale (PRF too high or low)
bad adjustment of pulsed doppler scale–innacuracy in measuring velocities
inappropriate update timing

52
Q

d

A

if colour scale is too high there will be no aliasing. the flow will be laminar. if the colour scale is too low it will all be aliasing. need to find the middle ground

53
Q

w

A

if colour scale is too high you might miss trickle flow. need to turn it down

54
Q

w

A

increasing sweep speed will allow you to examine the spectral better i.e. if patient has tacky.

55
Q

what is update timing?

A

change from one image modality to another. colour to pulsed

56
Q

power doppler

A

can confirm the absence of hypo echoic plaque

57
Q

what angle is 2d best at and for doppler?

A

90

60

Vascular Lab (5 decks)

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