Chapter 87 - Cerebrovascular disease unstable plaque

Question 1

Asymptomatic lesion stroke risk based on degree of stenosis

ACAS and ACST

Answer 1

no clear evidence

Question 2

Percentage of asymptomatic patients with carotid stenosis with identifiable intraplaque hemorrhage or fibrous cap rupture

Answer 2

50%

but only 2% stroke at 1 year
more than just morphology is involved

Question 3

Wall shear stress

Answer 3

frictional force on luminal surface by flowing blood

Question 4

plaque wall stress

Answer 4

blood pressure induced forces on plaque

Question 5

Gray-Weale classification of B-mode ultrasound on carotid

Answer 5

TYPE 1: pure hypoechoic
TYPE 2: hypoechoic with small hyperechoic areas
TYPE 3: hyperechoic with small hypoechoic areas
TYPE 4: hyperechoic pure

TYPE 1 and 2 more likely to have symptoms

Question 6

Juxtaluminal black area

Answer 6

necrotic core appearing near luminal surface

larger size = higher stroke risk

Question 7

Pixel distribution analysis

Answer 7

used to digitally quantify plaque morphology

Question 8

3D carotid ultrasound

Answer 8

allow plaque volume measurement

Question 9

Contrast enhanced ultrasound (CEUS) key points

Answer 9

1) inert gas bubbles 1-10 microns
2) increased neovascularization will enhance on CEUS as sign of unstable plaque
3) contrast are ingested by monocyte and adherent to inflamed endothelium up to 30 min

Question 10

Plaque strain measurement

Answer 10

1) ultrasound elastography
2) detect strain in two planes both longitudinal and radial
3) being used in CREST 2

Question 11

IVUS for carotid

Answer 11

dangerous procedure not clear benefit

Question 12

MRI for histomorphology

Answer 12

under study CREST 2

combination with US to produce biometric has potential