Transcript Carotid, ICA, ECA, Vertebrals, Circle of Willis

Doppler Sonography of
the Neck
Common Carotid Artery, Internal Carotid Artery, External
Carotid Artery, Vertebral Artery
Harry H. Holdorf
Ph.D., MPA, RDMS (Ab, OB, BR) RVT, LRT(AS)
Table of Contents
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Anatomy
Indications for Ultrasound
The Ultrasound examination
2-D
 Color Doppler
 Spectral Doppler
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Diagnostic Criteria
Indications for Ultrasound
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Evaluation of patients with TIA
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Evaluation of patients with CVA
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Transient Ischemic Attack
Cerebrovascular Accident
Evaluation of carotid bruits
Follow up of known disease
Monitor endarterectomy results
Evaluation of pulsatile neck mass
Carotid Ultrasound Examination
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Patient supine
Neck slightly extended
Head slightly turned away from side being
scanned
Linear transducer, 5-12 MHz
Protocols vary between operator, institution
B-mode, color Doppler, pulsed Doppler
Carotid Ultrasound Examination
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B-mode images – Transverse/Sagittal
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Color/Doppler
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Images from proximal CCA to bifurcation
Bulb – widening of CCA near bifurcation
Bifurcation – identify and ICA and ECA
Proximal/Mid/Distal CCA
Bifurcation (color)
Prox/Mid/Distal ICA
ECA
Vertebral
More images for pathology
Anatomy
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Aortic Arch
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Innominate or Brachiocephalic artery
Right subclavian artery
 Right common carotid
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Left common carotid artery
 Left subclavian artery
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CCAs lie
posterolateral to thyroid
 Deep to sternocleidomastoid muscle
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Anatomy
Anatomy
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Right CCA originates from innominate artery
Left CCA originates from aortic arch
CCAs divide into ECA and ICA
ICA has no branching vessels in the neck; may have
slight dilation just past its origin; supplies face and
head; lies posterior in the neck
 ECA has branching vessels; usually smaller than ICA
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Vertebral Arteries – lie between transverse
process of the vertebrae
Answers to previous slide
Aortic arch angiogram
 1. Innominate art.
 2. Right subclavian art.
 3. Right common carotid art.
 4. Right vertebral art.
 5. Left common carotid art.
 6. Left vertebral art.
 7. Left subclavian art.
Muscles and Fascia of the Neck
Deep dissection of neck.
BIF = bifurcation,
SCM= sternocleidomastoid,
TM= trapezius muscle
Common Carotid Artery
Carotid Bifurcation
Carotid Bulb with plaque
Carotid Bulb with Stent
CCA: Anterior Circulation
ICA
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The internal carotid artery supplies the brain, the eye, the forehead, and part of the nose. It enters the cranial
cavity via the carotid canal in the temporal bone.
It gives off no branches within the neck region.
The internal carotid artery supplies perfusion to the anterior and middle portion of the brain, the eye and its
appendages and sends branches off to the forehead and nose. It originates at the carotid bifurcation and
courses, via a
number of curvatures, through the base of the skull into the Circle of Willis.
The proximal-most portion of this vessel is rather bad bulbous and is referred to as
the bulb. Distal to the bulb, the artery narrows and is referred to as the ICA
proper.
Anatomically, the ICA is distinct from the ECA in that there are no branches until it passes through the base of
the skull.
After coursing anteriorly to the transverse processes of the first three cervical vertebrae (C1 –C3), it enters the
carotid canal of the petrous portion of the temporal bone.
The intra-petrous portion of the ICA is also referred to as the cavernous portion of the ICA.
After coursing through the base of the skull, its first branch arises, the ophthalmic
artery, which supplies blood to the retina. (This is of clinical importance when
discussing amaurosis fugax).
At the base of the brain, the ICA gives rise to the
anterior and middle cerebral arteries. The site of this branching is often referred to as the carotid siphon.
External Carotid Artery
External carotid artery.
 Superior thyroidal and lingual artery branches
are seen in the submandibular space.
 The superficial temporal artery lies anterior to
the ear.
Vertebral Artery
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Subclavian Steal
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When a stenosis or
occlusion of a the
proximal
subclavian or
innominate and
the effected side
“steals” blood
from retrograde
vertebral artery
flow
Vertebral Artery
Distinguishing characteristics of the vertebral
artery:
 First branch off subclavian
 Enters foraminal canal at C6
 Asymmetrical size: left > right
 Low resistance flow
Carotid Ultrasound Examination
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Differentiate ICA/ECA
ICA is usually lateral
 ICA usually larger than ECA
 ECA has branches
 Temporal tap – tapping of superficial temporal
artery in the pre-auricular area; will appear as “sawteeth” on spectral waveform
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Carotid Ultrasound Examination
Gray Scale Image
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Gray-Scale Image
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Vessel Wall Thickness
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IM Complex - .8 mm may be considered abnormal
Plaque Characterization
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Homogeneous – smooth surface, uniform echogenicity (p 953)
Calcified – echogenic with posterior shadowing (p 954)
Heterogeneous – complex with at least one sonolucent area
corresponding to at least 50% of plaque volume (p 955)
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Interplaque hemorrhage – “Swiss cheese” appearance
Plaque ulceration – focal depression/break in surface; or anechoic area
that extends to plaque surface; use color/power Doppler (p 952)
Some soft plaque may be very difficult to see on US
Evaluation of Stenosis – % stenosis by diameter/area –
taken in transverse plane (p 957)
ICA: Duplex characteristics of the ICA. Low
resistance waveform. Here a clear spectral window is
seen under the spectral envelope.
Carotid Ultrasound Examination
Color Doppler
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Color assignment depends on direction of flow
relative to the transducer
Color saturation indicates variable velocities
Lower velocities depicted toward baseline, usually
deeper shades
 Higher velocities usually brighter shades/colors
 Tagging of high velocities
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Gain/Scale settings
Duplex characteristics of the ECA . Rapid
systolic upsweep with high resistance flow
pattern during diastole. “Temporal tapping” can
be seen as spectral oscillations during diastole.
Carotid Ultrasound Examination
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Altered flow patterns
Pathology
 Normal
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At area where vessel branches
 Where diameter of vessel changes
 Tortuosity
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High flow jets after stenosis
Low trickle flow
Carotid Ultrasound Evaluation
Spectral Analysis
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Graphic display of velocities and direction of
moving red blood cells in the sample volume
X axis, Y axis
Direction of flow
Amplitude of “velocity component” (# of RBCs
within each velocity component = brightness of
the trace)
Spectral window – black zone between baseline
and spectral line
CCA Spectral Analysis
Carotid Interpretation
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Spectral Broadening – occurs when blood cells
move with a wider range of velocities; normal
spectral window will be filled in
Increases in proportion to the severity of stenosis
 Do not confuse with over gain or vessel wall motion
 See Rumack p 960 Fig 25-18
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Carotid Interpretation
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Doppler cursor should be in the center of the
vessel, parallel to the vessel walls; on high
velocity jets
Doppler angles 60 degrees or less
Doppler samples obtained just proximal to, at
and just beyond stenosis
1 cm intervals distal to plaque
Carotid Ultrasound
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ECA – feeds high resistance vascular bed;
velocity rises sharply during systole, falls quickly
during diastole
ICA – feeds lower resistance brain circulation;
large quantities of flow continue during diastole;
supplies brain; velocities usually increase from
prox to distal
CCA – resembles ICA waveform, with diastolic
flow above the baseline
Carotid Ultrasound Examination
Diagnostic Criteria
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Carotid artery stenosis (%)– reduction in diameter
Carotid artery occlusion
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No flow detected with color, pulsed Doppler
Thrombus/plaque fills vessel lumen
Reversal of flow proximal to occluded segment
Plaque characterization – as discussed above
Numerical values of some diagnostic criteria may very
between institutions
See Rumack p 960
Carotid Ultrasound Evaluation
Diagnostic Criteria
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Degree of stenosis assessed using
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ICA pre-systolic velocity
ICA End Diastolic velocity
PS ICA/CCA ratio
PED ICA/CCA ratio
No established criteria for grading ECA stenosis - occlusive
plaque in ECA is less common and rarely clinically significant
(Rumack)
Velocity criteria used to grade CCA stenosis have not been
well established (Rumack)
See Rumack p 967
Carotid Ultrasound
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> 50 % - mild stenosis; not hemodynamically
significant
50 - 69% moderate stenosis; follow up for progression;
hemodynamically significant
70 – 99% - severe stenosis; operable lesion
Occlusion – concern regarding hemodynamic status of
intracranial circulation, not an operable lesion
Ulceration – considered clinically significant; can
rupture or hemorrhaging; plaque can continue to
embolize or occlude ICA
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Superficial temporal artery:
Terminal branch of ECA.
Supplies skin over frontal and temporal regions of
scalp.
The superior temporal artery, which can be palpated just anterior to
the pinna of the ear, is sometimes examined using duplex
ultrasound in patients with suspected temporal arteritis.
TEMPORAL TAP METHOD
The Superior Temporal Artery
Circle of Willis (connecting the two)
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Major collateral pathway of brain
Basilar artery formed from fusion of both vertebrals
Internal carotid arteries
Anterior cerebral
Middle cerebral
Basilar artery
Posterior cerebral
Communicating vessels
Anterior communicating artery
(acoa)
Posterior communicating artery
(pcoa)
Circle of Willis
Posterior Circulation
References
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Araki, C.T. Introduction to Non-Invasive Vascular Testing. UMDNJ Vascular
Technology Program.
Rumack C., Wilson, S. & Carboneau. Diagnostic Ultrasound, 4thEdition, Vol 1. 2005.
Image slide 4 retrieved on November 27th, 2012 from
http://www.vascularultrasound.net/vascular-anatomy/arteries/extracranial
Image slide 6 retrieved on November 27th 2012 from
http://www.medison.ru/uzi/eho41.htm
Image slide 7 rwetrieved on November 27 2012 from
http://www.specialistvascularclinic.com.au/carotid-interventions.html
Image slide 8 retrieved on November 27th from
http://www.medicern.co.uk/products/Colour-Portable-Ultrasound/M7-ColourDoppler-Portable-Ultrasound.html
Image slide 10 retrieved on November 27th from
http://www.ultrasoundpaedia.com/normal-carotids/
Image slide 24 retrieved on November 28, 2012 from
http://www.ajronline.org/content/177/1/53.figures-only