2. WHAT IS CAROTID ULTRASOUND?
• Carotid ultrasound is a painless and harmless test that
uses high-frequency sound waves to create pictures of
the insides of your carotid arteries.
• You have two common carotid arteries, one on each
side of your neck. They each divide into internal and
external carotid arteries.
• The internal carotid arteries supply oxygen-rich blood to
your brain.
• The external carotid arteries supply oxygen-rich blood
to your face, scalp, and neck.
3. INDICATION FOR CAROTID ULTRASOUND
• Transient ischemic attacks
• Carotid Bruit
• Stroke
• Follow-up of known carotid stenosis
• Post intervention follow-up (Carotid endarterectomy,
stent, etc.
• Trauma in the distribution of carotid artery
4. IDENTIFICATION OF ICA & ECA
• The CCA on the right arises from the innominate artery
behind the right sterno clavicular joint, where the origin can
usually be seen on ultrasound.
• On the left the CCA arises directly from the aorta ,so that
its origin one the left cannot be seen on scanning from the
neck.
• The level of carotid bifurcation is usually at about the level
of the upper border of the laryngeal cartilage but it may vary
considerably.
• The two branches of CCA are ICA & ECA.
• It is essential that they are identified positively.
5. IDENTIFYING FEATURES OF ECA & ICA
Features ECA ICA
Size usually smaller Usually larger
Branches Yes No
Orientation proceeds anteriorly
towards face
Proceeds posteriorly towards
mastoid process
Doppler
characteristics
High resistance
pattern with
relatively little diastolic
flow.
Low-resistance with high
diastolic flow.
Temporal Tap waveform
deflections(positive
No waveform
deflection(Negative)
8. WAVEFORM ANALYSIS NORMAL CAROTID ARTERY
combination of ICA and ECA patterns,
• intermediate amount of continuous forward diastolic
flow
• a sharp systolic upstroke and thin spectral envelope
• flow below the baseline or filling in of the spectral
window normally should not be seen
9. ICA
• a low‐resistance waveform pattern
• systolic peak should be sharp and the spectral envelope thin
• continuous forward diastolic flow
• the systolic peak may be slightly blunter than the systolic peak of the ECA
10. ECA
• the systolic upstroke is sharp
• the spectral envelope is thin.
• reduced to no diastolic flow
• diastolic flow should be symmetrical bilaterally
• Transient reversal in early diastole (characteristic early diastolic notch ) ‐a
normal finding
11. PATIENT POSITION
• supine or semi supine
• head slightly hyper‐extended
• rotated 45°away from the side being examined.
• Higher‐frequency linear transducers (7 MHz)
Limitations
• short muscular neck
• a high carotid bifurcation
• tortuous vessels
• calcified shadowing plaques
12. VERTEBRAL ARTERIES
• The vertebral artery on each side is the first branch of
the sub clavian artery.
• The vertebral arteries are most easily located by
placing the transducer longitudinally over the CCA &
angling it medially so that the vertebral bodies are
identified. The transducer is then moved laterally so
that the transverse processes of the vertebrae & the
spaces between them are visualized, the vertebral
artery & vein may then be seen in these gaps.
13. VERTEBRAL ARTERY
• low resistance wave pattern
• forward diastolic flow
• no systolic or diastolic notch
• similar to carotid in flow (color)
• no reversal of wave form
The vertebral arteries can be variable in diameter.
They should always demonstrate ante grade flow
(toward the brain) and be low resistance similar to
the ICA.
14. SUBCLAVIN STEAL SYNDROME
• Subclavian artery steno‐occlusive
disease proximal to the origin of the
vertebral artery.
• Resulting in decreased blood
pressure in the arm distal to the
steno‐occlusive disease.
• Causes lateral vertebral artery
blood flow alteration
• Severe stenosis, flow reversal
occurs in the lateral vertebral artery
as compensatory collateral to the
vascular territory beyond the
subclavian steno‐occlusive lesion.
15. CLASSIFICATION BASED ON VERTEBRAL ARTERY
HEMODYNAMICS
(stage I): reduced ante grade vertebral flow.
(stage II): reversal of flow during reactive
hyperemia testing of the arm.
(stage III): permanent retrograde vertebral flow.
16. CAROTID PLAQUE
• Defined as a localized protrusion from the wall into the lumen
with an area 50% greater than the intima ‐media thickness of
neighboring sites.
• low and high echogenic plaque.
• heterogeneous or homogeneous.
• regular (smooth) or irregular.
17. • If more than 20% of the plaque echogenicity differed from the echogenicity of
the rest of the plaque by two or more echogenicity grades –is
heterogeneous.
• When height variations between 0.4 and 2 mm along the contour of the
lesion –is irregular
• Ulcerated plaques‐recesses in the contour of the lesion at least 2 mm in
depth, with a well‐defined back wall at the base showing flow.
18. PLAQUE CLASSIFICATION
• Class I , homogeneous texture, uniformly hypo echoic
• Class II , heterogeneous texture, predominantly hypo echoic
• Class III , heterogeneous texture, predominantly hyper echoic
• Class IV , homogeneous texture, uniformly hyper echoic
• Class V , unclassified calcified plaques
19. DISSECTION
• Trauma ‐seat belt injury or repetitive trauma.
• •Occasionally, spontaneous and isolated to the carotid arteries in Marfan
syndrome, Ehlers‐Danlos syndrome, fibromuscular dysplasia, hypertension, or
drug abuse
• •Also ‐direct extensionof an aortic dissection.
• •Rare but, dissection of the ICA is the most common cause of stroke in young
patients.
• •Most ICA dissections occur at the level of the carotid bifurcation.
• Thrombosis of the false lumen ‐mimic stenosis
• The waveform may be indistinguishable from a stenosis except that typically it
extends over a much longer segment and often no plaque is visualized.
20. • The presence of early diastolic flow reversal
in the lateral CCA .
• Reduced peak systolic and diastolic
velocities in the lateral ICA.
• are non‐specific, but warrant a search for a
cause of increased peripheral vascular
resistance.
• Heterogeneous plaques and ulcerated
plaques are unstable or friable.
• Potential for embolic TIA and .
• cerebro‐vascular accidents.
21. INTIMA MEDIAL THICKNESS
The intima-medial thickness
(IMT) has been widely used as
one of the parameters of
atherosclerosis . The IMT is
measured on a two-dimensional
(2D) gray-scale image. The
optimal gray-scale image of the
longitudinal scan of the carotid
artery, which passes by the
center of the carotid artery,
shows two bright interfaces
along the artery wall.
22. • In the far wall, the upper bright line is
the interface between the blood and
intima, and the lower bright line is the
interface between the media layer and
adventitia layer. The interface between
the intima and media does not produce
any interface. The distance between the
upper and lower bright line represents
the thickness of the intima and media
layer.
• In one study, the success rate for far
wall measurement was 89 % (109/122)
in the common carotid artery and 38 %
(140/366) in the ICA . The IMT should
be measured on a segment without a
focal lesion.
23. • The image should be magnified as much as possible to
make the measurement easier to perform.
• Normal IMT is <0.80 mm.
