1. anatomy: draw (where will plaque ... - clinical ultrasound · 19/08/2019 1 carotid artery...
TRANSCRIPT
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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 ?