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Carotid Artery Ultrasound

1. Anatomy: Draw (where will plaque form?)

Anatomical variations: CCA

• High bifurcation (1-2%)

• Branch

• Rare anomalies

Differentiating ICA/ ECA - ?

• Temporal tap

• Presence of a branch

• Waveforms

? What’s odd? Anatomical variations: ICA

• Branch

• Agenesis

• Postero-lateral (38%)

• Posterior (38.5%)

• Postero-medial (23.5%)

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Why do we do this examination? Carotid Colour Duplex Ultrasound: CVA

• Haemorrhagic (20%)

• Embolic/Ischaemic (80%)– 50% Cardio-embolic

– 50% Carotid

• Plaque

– Composition

• Shearing force

– Stenosis (PSV)

Carotid Colour Duplex Ultrasound: CVA

• Haemorrhagic (20%)

• Embolic/Ischaemic (80%)– 50% Cardio-embolic

– 50% Carotid

• 2 TASKSMorphology

Haemodynamic

BACKGROUND

Transient Ischaemic Attack (TIA)

• Numbness

• Clumsiness

• Weakness

• Paralysis of the face, arm or

leg on one or both sides.

• Dizziness (in particular ‘head

spins’), loss of balance or an

unexplained fall.

• Loss of vision in one or both

eyes.

• Headache, usually severe and

sudden.

• Difficulty swallowing.

• Nausea or vomiting.

STROKE: Clot Retrieval – MMC and RMH

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How to prevent a stroke?

• Lifestyle

• Medication

• High Grade

– Remove the plaque

• How / When?

– Later

Carotid CD US: The AIM- US Examination

• 2 TASKS

• Evaluate the plaque

• Assess the shearing force

– Grading of Stenosis

– Haemodynamics

Carotid CD US: The Procedure

• B-mode

• Colour

• Spectral

Setting Up: Ergonomics

• Typical

• Elbow location

Setting Up: Ergonomics

• Upside down

Potential Technique Pitfalls

• Over extension

• Over rotation

• Origins

• Uni-planar

• Criteria

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Potential Technique Pitfalls

• The problem

Potential Technique Pitfalls

• The problem

Potential Technique Pitfalls

• Transducer

– Curvi-linear

– L7-4

• B-mode

– Gain too low

– Dynamic Range

• Colour

– Inflexibility

• Spectral

– Sweep speed

What protocol : Your department ?

Imaging: What protocol

• B-mode

– Transverse

CCA, Bif’n, ICA/ECA

– Sagittal

CCA, ICA, ECA

• Morphology

• Measure

Imaging: Colour

• Colour

– Filling defects

– Aberrant filling

– Aliasing

– Ulcer

• Under-utilised

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Imaging: Spectral

• Spectral

– CCA (2),

– ICA (3),

– ECA,

– Vertebral, SCA

• Representative

The Information

• TASK 1. Morphologic

Morphologic: Intimal thickening

• IMT > 0.8 mm

• Correlates with

– Stroke

– Cardiac disease

++

Plaque Characterisation

• Hypoechoic- Fine Ca++

• Hypoechoic/Homogenous Tegos TJ Eur J Vasc Endovasc Surg 2002

• Hypo/ Heterogeneous

• Hyper/ Hypoechoic

• Calcific

• Irregular

– 1.8x Rothwell, Stroke 2000

• Ulcerated

• Documentation

Morphologic: Vunerable…. Morphologic: Too late?

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Morphologic: Ulceration Morphologic: Ulceration

Morphologic: Need to describe

& ? Ulcer

Terms: Soft / Hard

The Information

• TASK 2. Haemdynamic

Haemodynamic Information

• PSV

• EDV

• Ratios

• Spectral Broadening

• Which criteria ?

Validated data

Professional standards

Published data

What does your department use?

Which criteria – Your department?

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Which chart – MONASH? Ultrasound: ICA stenosis classification

• 1987 Washington criteriaStrandness JCU 1987

• Multiple papers

• 1997: RANZCR

• 1998: ASUM

• 2002 USA Consensus statement

• Haemodynamic

• Morphologic

How do you classify the CCA?

• No significant studies

– % Diameter

– Nascet

– 2:1 ratio … > 50 %

ECA – Do we care?

How do you classify the ECA?

• Literature Paivansalo MJ Acta Radiol.1996

– ECA > ICA

• PSV > 150cm/s

– (125-175 cm/s)

• Not ICA criteria

• Morphology

Theoretically…do we use an angle?

a. As close to 60 degrees as possible

(while remaining < than 60 deg)

b. 30-60 degrees

c. 0-60 degrees

d. None of the above

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Theoretically…do we angle:

a. Parallel to the walls of

the artery

b. Along the direction of

flow

c. Parallel to the plaque

border

d. Any of the above

e. Non of the above

The Information

• BONUS TASK. Does it all make sense?

Of note…

• Report in classifications

• Note/ Report discordance

Measurement How/ Why?

• % diam red’n

• Nascet

• ?

Measurement How/ Why? Example Case

• 72 yo Male

• Asymptomatic

• Pre CABG’s

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Example Case Example Case

What will happen to the patient?

• Neurologists / Vascular Surgeons

• Make some decisions

• CTA Gold Standard BUT….

What will happen to the patient?

• General Rules

– Symptomatic

Medication

50-69%– Consider Endarterectomy

– Plaque morphology (Vulnerable?)

>70%– Endarterectomy

– Asymptomatic F/U

Risk assessment

REMEMBER

• What we do matters

• Technical skills

• Limitations..

– Further imaging

Other Stuff

• Carotid Body Tumour

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Other Stuff

• Bypass grafts

Other Stuff

• Bypass grafts

Retropharyngeal

CCA - SCA

• Occlusion

• Resistive CCA

• No ICA flow

• Asymptomatic

– Low risk

Other Stuff The Occlusion Vs Trickle

• 8% false +ve

• Contrast

• Why is this important?

The recanalised occlusion

• Pseudostring Sign from Vasa Vasorum Collaterals Kriegshauser JS et al J

Ultrasound Med 22:959–963, 2003

Other Stuff

• Dissection

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Other Stuff

• Dissection

Other Stuff

• Non-occlusive Thrombus

Other Stuff

• Carotid Endarterectomy

• Pre Surgical criteria

– Does NOT apply

• Morphology

• Velocities

• SURVEILLANCE

• Reduced Classification

www.vesalius.com

Other Stuff

• Carotid Endarterectomy

Other Stuff

• Carotid Stents

• PSV >150 cm/s

• ICA/CCA ratio >2.2

Hobson BK et al J Vasc Surg

Draw the 3 vertebral waveforms that indicate a potential Subclavian Steal

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Conclusion Subclavian Steal: Which is more common?

Subclavian Steal Subclavian A

• Protocol ?

• Vertebral pathology

• Waveform analysis

Dissection ?