Carotid Doppler

Doppler ultrasound of carotid arteries by Dr. Sulav Pradhan

1. Doppler ultrasound
of carotid arteries
Dr Sulav Pradhan
2
nd
year MD Resident
Dept. of Radiodiagnosis
NAMS, BIR Hospital

2. Outline
•Introduction
•Anatomy of carotid arteries
•Normal Doppler US of carotid arteries
•Causes of carotid artery disease
•Effect of extra-carotid diseases

3. Introduction
•Stroke secondary to atherosclerotic disease is
the third leading cause of death in the United
States.
•Ischemia from severe, flow-limiting stenosis
caused by atherosclerotic disease involving the
extracranial carotid arteries is implicated in
20% to 30% of strokes.

4. •Carotid atherosclerotic plaque with resultant
stenosis usually involves the internal carotid
artery (ICA) within 2 cm of the carotid
bifurcation.
•This location is readily amenable to
examination by sonography as well as surgical
intervention.

5. •Carotid endarterectomy (CEA) initially proved
to be more beneficial than medical therapy in
symptomatic patients with carotid stenoses of
more than 70%.
•Subsequent NASCET results for moderate
stenoses have shown a net benefit for surgical
intervention with carotid narrowing between
50% and 69% of vessel diameter.

6. •Accurate diagnosis of carotid stenosis clearly is
critical to identify patients who would benefit
from surgical treatment.
•In addition, ultrasound can assess plaque
morphology, such as determining
heterogeneous or homogeneous plaque,
known to be an independent risk factor for
stroke and transient ischemic attack (TIA).

7. Carotid Artery Anatomy
•Right CCA (Comon Carotid artery) arises from
bifurcation of innominate artery. Left CCA arises from
aortic arch.
•CCAs ascend anterolaterally up the neck medial to
jugular vein and lateral to thyroid.
•Each artery measures 6-8mmin diameter.
US(Ultrasound) evaluation of CCA demonstrates 3
layers of normal vessel wall—echogenic intima,
hypoechoic media and echogenic adventitia.

8. •CCA dilates in common carotid bulb and bifurcates
into ICA and ECA at C3-C4 level.
•ECA assumes an anteromedial course off the carotid
bulb 70% of time. It has branch vessels that supply
head and face and measures 3-4mmin diameter.
•ICA assumes posterolateral course ,supplies brain and
measures 5-6mm.
•Portion of arterial wall between ICA and ECA at their
origin is called flow dividers.

9. Internal Carotid Artery
•There are 7 segments in
the Bouthillier
classification:
–Cervical segment
–Petroussegment
–Lacerumsegment
–Cavernous segment
–Clinoidsegment
–Ophthalmic (supraclinoid)
segment
–Communicating (terminal)
segment

10. BRANCHES
•C1 : cervical segment -
none
•C2 : petroussegment
–Caroticotympanicartery
–Vidianartery
•C3 : lacerumsegment -
none
•C4 : cavernous segment
–Meningohypophysealtrunk
–Inferolateraltrunk
•C5 : clinoidsegment -
none
•C6 : ophthalmic segment
–Ophthalmic artery
–Superior hypophysealartery
•C7 : communicating
segment
–Posterior communicating
artery
–Anterior choroidalartery
–Anterior cerebral artery
–Middle cerebral artery

11. Variants resulting from elongation of ICA

12. EXTERNAL CAROTID ARTERY
•Branches:
1.Superior thyroid artery
2.Lingual artery
3.Facial artery
4.Ascending pharyngeal
artery
5.Occipital artery
6.Posterior auricular artery
7.Internal maxillary artery
8.Superficial temporal artery

13. Vertebral Artery
•Vertebral artery is the first
branch of the subclavian
artery, arising from the highest
point of the subclavian arch.
•At the sixth cervical vertebra,
the vertebral artery runs
posteriorly to travel upward
through the transverse
foramen of cervical vertebrae.

14. Variation of vertebral aretery:•Origin: Left VA arising directly from aortic arch
(6-8%).
•Course: can pass through foramen
transversarium of C7 (10%)
•Size: equal in size( 26%), left is larger (42%),
right larger than left(32%).
•One VA may be hypoplastic or congenitally
absent.
Termination: B/L VA joins to form basilar artery
•VA may terminate in PICA rarely.

15. Anatomy of carotid arteries
Normal Doppler US of carotid arteries
Causes of carotid artery disease
Effect of extra-carotid diseases

16. Carotid sonography is the first imaging modality
used in the investigation of extracranial vascular
system becoz it is inexpensive,quick,and
noninvasive.

17. Indications of carotid ultrasound
•Evaluation of pts with TIAs
•Evaluation of pts with CVA
•Evaluation of carotid bruits
•Follow up of known disease
•Monitor endarterectomy results/stents, bypass
•Preoperative screen prior to major vascular surgery
•Evaluation of potential source of retinal emboli
•Evaluation of pulsatile neck mass
•Follow up of carotid dissecton

18. Technique
•Performed with the pt.in supine position
using a linear 5-10MHZ transducer.
•Pts head is rotated away from the side being
examined.
•Gel is applied along sternomastoid muscle
and probe is placed on the neck at the level
of clavicle.CCA will be imaged at this
level,document in longitudinal plane any
plaque that may be present within the vessel.
•Transverse imaging is helpful in determing
ideal long axis and obliquity by showing ICAs
and ECAs as they bifurcate from bulb.

19. All carotid artery examinations should be
performed with:
•Gray-scale US
•Color Doppler
•Power Doppler
•Spectral Doppler
Integrate gray scale, color flow, & spectral
findings

20. •Avoid excess pressure on carotid bifurcation to
avoid
Stimulation of carotid sinus :
Bradycardia
Syncope
Ventricular asystole
•Compress arteries to cause spurious high
velocities

21. Grey scale images
•Vessel wall thickness
•Plaque characterization

22. Color Doppler
•Useful tool during initial examination process and is
especially helpful in identifying extra cranial vessels.
•Based on pulsed ultrasound technology.
•Frequency shift information obtained by color doppler
is displayed as colors on the screen, usually red and
blue depending on direction of blood flow.
•Color doppler should be used in addition to pulsed
doppler to determine areas of stenosis or turbulent
flow.

23. Advantages:
•With color it is possible to visualize small amount of flow in
unexpected areas because doppler signals are strong at angles
0-60.
1.Vessels identification is rapid.
2.Site of critical stenosis can be visualized and doppler sample
gate can be placed at appropriate angle to correspond within
the flow.
4 Visualization of good color fill from wall to wall within vessel
eliminates need to perform a spectral analysis at many
locations while moving the sample volume throughout the
length of vessel.

24. Disadvantages:
•Angle dependent
•Resolution less than gray scale
•Slow frame rates information

25. Power Doppler
•Power doppler US utilizes a larger dynamic
range with a better signal to noise ratio than
color doppler US.
•Because power doppler US doesn’t evaluate
frequencies but rather amplitude or power,
artifacts such as aliasing don’t occur.

26. Advantages:
•NO aliasing
•Potentially increases accuracy of grading stenosis.
•Aids in distinguishing preocculsive from occulsive lesions
•Potential superior depiction of plaque surface morphology
•Increased sensitivity in detecting low velocity, low amplitude
blood flow
•Angle independent
Disadvantages:
•Doesn’t provide direction or velocity flow information
•Very motion sensitive

27. Pulsed Doppler Spectral analysis
•CCA: Spectral doppler examination begins by
locating CCA in longitudinal plane. Begin low
down in the neck and image the most proximal
segment of the vessel.
•Doppler sample volume is placed in middle of
artery, maintaining an angle of 60.Doppler
angle must be kept b/w 45-60 degree for
interpretable signal.

28. •A small gate of 1.5-2mm increases the
likelihood of obtaining good central vessel
laminar flow information without including
slow flowing signals from blood near vessel
wall that produces spurious broadening.
•Proximal CCA normally has a very turbulent
flow because of a change in flow direction as
blood enters carotid from subclavian artery.

29. •Flow in Mid CCA is taken at an area where a 60
angle can easily be obtained.
•Accuracy is most important because this
velocity is used to calculate ICA/CCA ratio.
•Ratio is particularly helpful when there are very
high velocities in ICA or there are diminished
velocities throughout carotid system due to
poor cardiac output.

30. Intima-Media complex
Normal value ≤ 0.8 mm
Wall of CCA, bulb, or ICA
Best measured on far wall
Only intima & media included

31. Carotid bNormal carotid bifurcationifurcation
Longitudinal B-mode image of carotid bifurcation
ICA & ECA seen in same plane

32. Gray Scale
ICALarger & lateral
ECASmaller & internal
Color Doppler ultrasound

33. Differentiating ICA from ECA

34. Internal & external carotid artery
2 small branches originating from ECA
Power Doppler US

35. Standard Doppler spectral examination
Traces obtained from
•CCA Proximal –Distal
•Carotid Bulb
•ICA Proximal –Middle –Distal
•ECA Proximal
•Vertebral Artery V0 –V1 –V2
•SCA

36. Typical normal Doppler spectra
Common carotid artery
Internal carotid artery
External carotid artery
PSV: 45 –125 cm/sec
Difference between 2 sides < 15 cm/sec

37. Temporal tap maneuver, Temporal tapping of ECA
“Saw-tooth” appearance

38. Coiling of ICA Congenital -Bilateral -Symmetrical

39. Abnormal Doppler flow in tortuous vessel
Tortuous CCA displays color
Doppler eccentric jets of flow
High velocity due to eccentric
jet in tortuous CCA
Tortuosity can increase velocity, although there is no stenosis
This is due to difficulty in obtaining a correct insonating
angle, non-linear or helical flow.

40. Ectatic CCA
Ectatic CCA as it arises from inominate artery
Responsible for pulsatile right supra-clavicular mass

41. Protocol for Vertebral artery
Longitudinal VA between transverse processes
•Direction of flow
•Waveform configuration
•Measure PSV
•Follow artery cauded to its origin
•
•Follow artery cephalad above transverse
processes

42. Technique of localizing vertebral
artery
•Locate CCA in longitudinal plane.
•Direction of flow in CCA and Jugular vein
determined.
•Gradual lateral sweep of transducer
demonstrates vertebral artery and vein
between transverse process of C2 and C6
(posterior acoustic shadowing).
•Angle the transducer caudally to visualize
vertebral artery origin in 60-70% of cases (80
on right and 50 on left).

43. Vertebral artery
•Cephalad flow throughout cardiac cycle
•Low resistance flow pattern
•Size: variable & asymmetric –Mean diameter
4 mm
•PSV: 20 –40 cm/sec –<10 cm/sec potentially
abnormal
Vertebral vein
•May occasionally be seen adjacent to VA
•Flow caudad & nonpulsatile
•

44. Normal vertebral artery & vein
V2
Vertebral artery & vein seen between vertebral processes of spine
Color Doppler Pulsed Doppler

45. Plaque types
•Type1-predominantly echolucent plaque, with a thin echogenic
cap.
•Type 2-Substantially echolucent with small areas of
echogenicity(>50% sonoluscent).
•Type 3—Predominantly echogenic with small areas of
echolucency(<50% sonoluscent).
•Type 4—Uniformly echogenic
•Type 1 and 2 heterogenous plaque/ association with
intraplaque hemorrhage and ulceration/ unstable/ abrupt
increase in plaque size after hemorrhage or embolization.
•Type 3 and 4 homogenous plaque/ predominantly composed of
fibrous tissue and calcification.

46. Heterogeneous plaque in internal carotid artery (ICA). A, Sagittal, and B,
transverse, images show plaque (arrows) virtually completely sonolucent,
consistent with heterogeneous plaque (type 1). Note smooth plaque surface. C,
Sagittal, and D, transverse, images show focal sonolucent areas within the
plaque greater than 50% of plaque volume, corresponding to heterogeneous
plaque (type 2). Note the irregular surface of the plaque.

47. Homogeneous plaque. A, Sagittal, and B, transverse, images show homogeneous plaque in left
common carotid artery (type 4).Note the uniform echo texture. C, Sagittal, and D, transverse,
images show homogeneous plaque in proximal left internal carotid artery (type 3). Note the focal
hypoechoic area within the plaque, estimated at less than 50% of plaque volume.

48. Calcified plaque

49. Calcified plaque
Calcific plaque with shadow
obscuring portion of the bulb
Interrogate artery beyond plaque
Shadowing segment < 1 cm
No turbulent flow: unsignificant stenosis
Damped or turbulent flow: tight stenosis
Shadowing segment > 2 cm
Other modalities recommended

50. Plaque Ulceration
•Ultrasound reliably detects intraplaque hemorrhage;
however cannot accurately identify ulcerated plaques.
•Ulcerated plaques are heterogenous.
•Virtually all ulcerated plaques are associated with
hemorrhages.
•A “Swiss cheese” plaque appearance with multiple
sonolucent areas-characterstic of intraplaque
hemorrhage.

53. Ulcerated plaque or twinkle artifact
Color in diastole
Color flow disappeared
Color artifact continues to twinkle
Hard plaque in proximal ICA
Flow at plaque surface

54. Evaluation of Stenosis
•Carotid diameter and stenosis area
measurement is done in transverse plane,
perpendicular to the long axis of vessel.
•Eccenteric plaque, due to partial voluming
effect may over or underestimate stenosis area
in longitudinal scan.
•Percentage of area stenosis and diameter
stenosis not always linearly related.
•Asymmetrical stenosis best assessed by area
stenosis.

55. Standard examination
•Rapid color Doppler screening
•Detection of abnormal flow patterns
•Placement of pulsed Doppler signal volume in
abnormal areas, esp those with high velocity
jets. (in region of and immediately distal to
area of high grade stenosis).

57. •If normal in gray scale, color or power Doppler study,
only representative spectral tracing from the CCA, ICA,
and ECA is done.
•Spectral tracing to be done from:
–Proximal and distal CCA
–Carotid bulb
–Proximal ECA
–Proximal, middle and distal ICA
–Vertebral arteries
•From proximal, at, and just beyond the maximal
stenosed area.
•At 1 cm interval distal to visualized plaque as
cephalad as possible.

58. Spectral Broadening
•Spectral window: normally a black zone is
present between the spectral line and the Zero
velocity baseline.
•With atheromatous plaque, spectral lines
become wider, filling in the normal spectral
window called spectral widening, which
increases in proportion to the severity of
carotid stenosis.

60. Pseudospectral Broadening
•Technical factors, high gain setting due to
excess noise If suspected, lower the gain to
see if spectral window clears.
•Vessel wall motion when Doppler sample
volume is too large or positioned too near the
vessel wall Decrease the size of the sample
volume and place in midstream.

61. Pseudo-spectral broadening
•High gain setting
•Vessel wall motion
•Tortuous vessels
•Site of branching
•Abrupt change in vessel diameter
•↑ velocity: athlete -high cardiac output –Arterio-
Venous fistula and Malformation
•Aneurysm, dissection, & Fibromusculardysplasia

62. High velocity blood flow patterns
•Carotid stenosis cause velocity change when there is
>50% diameter or >70% area stenosis.
•Velocity increases with increase in stenosis.
•Critical stenosis >95%, velocity may decrease with
dampened wavforms.
•Velocity increase is focal; most pronounced in or just
distal to stenosis.

63. . Internal carotid artery (ICA) stenosis. A, ICA stenosis of 50% to 69% diameter shows a peak systolic
velocity (PSV) of 129 cm/sec. B, Right ICA demonstrates a visible high-grade stenosis on color
Doppler with end diastolic velocities (EDVs) of greater than 288 cm/sec and PSVs that alias at
greater than 400 cm/sec. This is consistent with a very high-grade stenosis.

64. Assessment of Severity of stenosis
Best assessed using gray scale and
pulsed/spectral Doppler parameters.
•PSV/EDV of ICA/CCA.
•Peak systolic ICA/CCA ratio (SVR).
•Peak end diastolic ICA/CCA ratio (EDR).

65. Estimation of carotid stenosis
Diameter reduction Surface reduction

66. Relationship between diameter reduction
& cross-sectional area reduction
Diameter reduction
(%)
Cross-sectional area reduction
(%)
30 50
50 75
70 90

67. Grading of stenosis

68. Criteria for diagnosis of ICA stenosiswith gray scale
and Doppler US

69. Color Doppler bruit
•If the stenosis
produces a bruit or
thrill, the resultant
perivascular tissue
vibration is seen as
transient speckles of
color in adjacent soft
tissue, more
prominent during
systole.
Extensive soft tissue color Doppler
bruit surrounds carotid bifurcation
with 90% ICA stenosis
Confetti sign

70. Post-stenotic zone / Distal to site of stenosis
Tardus-parvus waveform

71. Sonographic features of severe ICA stenosis
•Significant visible plaque (≥ 70% diameter reduction)
•PSV > 230 cm/sec
•EDV > 100 cm/sec
•ICA/CCA PSV ratio ≥ 4.0
•Spectral broadening
•Color aliasing despite high velocity scale (100 cm/sec)
•Color bruit artifact in surrounding tissue of stenosis
•High-pitched sound at pulsed Doppler

72. Severe stenosis (70% to
near occlusion) of the ICA.
Duplex US image of the left ICA shows a
high PSV (366 cm/ sec), a significant
amount of visible plaque, the presence
of aliasing despite a high color scale
setting (114 cm/sec), color flow
turbulence immediately distal to the
stenotic segment, broadening of the
PW Doppler spectrum, and a high end-
diastolic velocity (182 cm/sec).

73. Tight stenosis or occlusion
•Difficult to distinguish tight stenosisfrom occlusion
•Completely occluded ICA
Will not release emboli
Not corrected by surgery
•Very severe stenosis
Potential source for emboli or acute thrombosis
May require urgent surgery

74. Optimization of low flow velocities
–Decreased color velocity scale
–Increase color, power & pulsed Doppler gain
–Decreased wall filter
–Focal zone at level of diseased segment
–Doppler angle as low as possible (60
°
or less)
–Increased persistence
–Increase sample volume gate

75. Subtotal occlusion of ICA
“string sign” or “trickle flow ”
Narrow channel of low-velocity in subtotal ICA occlusion
Low PRF & low filter required to detect low-velocity flow

76. High grade “string sign” stenosis
Tardus-Parvus waveform
Tardus:Long rise time
Parvus:Low PSV

77. Occlusion of ICA
•Absence of flow by color, power & pulsed Doppler
•“Internalization” of ipsilateralECA waveform
•Reversed flow in ICA or CCA proximal to occlusion
•Thrombus or plaque completely fills lumen of ICA
•Externalization of ipsilateralCCA or proximal ICA
•Higher velocities in contra lateral CCA vsipsilateral
CCA

78. Occlusion of ICA
ICA
ECA
CCA
Retrograde flow in stump of ICA
Absence of flow in ICA beyond
Doppler spectrum from CCA
Externalization of CCA

79. Occlusion of ICA
“to-and-fro” flow or thud flow
Damped systolic flow
Reversed flow in early diastole
Pulsed Doppler of CCA

80. Internalization of ECA
Patient with complete occlusion of left ICA

81. Stenosis of ECA
•Isolated ECA stenosis is not clinically insignificant.
PSV of ECA stenosis(cm/s)
Minimal <200
Moderate 200-300
Severe >300
% Stenosis ECA/CCA Systolic Ratio
<50 <2
<70 >=2

82. Occlusion of CCA
Reversed flow from ECA
to supply ICA & brain
“ECA-to-ICA collateralization”

83. Occlusion of CCA
Absence of flow in distal CCA
Reversed flow in ECA
Normal flow in ICA
Internalization of ECA
Delayed systolic acceleration (tardus)
Positive temporal tap maneuver

84. Schematic Doppler waveforms of VA

85. High-resistance flow in vertebral artery
High-resistance flow
No diastolic component
Distal VA stenosisor occlusion
Hypoplasticvertebral artery
Differential diagnosis:

86. Route of flow in left vertebral steal

87. Types of subclavian steal
Transient reversal of vertebral flow during systole
Converted to partial or complete by provocative maneuver
Pre-steal or bunny waveform
Striking deceleration of velocity in mid or late systole
High-grade stenosisof subclavianrather than occlusion
Incomplete steal
Complete reversal of flow within vertebral artery
Complete steal

88. Vertebral-to-subclavian steal
Presteal
Incomplete steal
Complete steal
Compared to bunny in profile

89. Provocative maneuver in steal syndrome
Conversion of pre-steal waveform to more pronounced steal
following deflation of pressure cuff
* Inflation of pressure cuff greater than systolic arterial pressure on ipsilateral arm
Inflation of pressure cuff on arm for 3 min & rapid deflation*
Pre-steal More pronounced steal

90. Limitations of carotid US examination
•Short muscular neck
•High carotid bifurcation
•Tortuous vessels
•Calcified shadowing plaques
•Surgical sutures, postoperative hematoma, central
line
•Inability to lie flat in respiratory or cardiac disease
•Inability to rotate head in patients with arthritis
•Uncooperative patient

91. •Anatomy of carotid arteries
•Normal Doppler US of carotid arteries
•Causes of carotid artery disease
•Effect of extra-carotiddiseases

92. Causes of carotid artery diseases
Arteriosclerotic disease
Non-arteriosclerotic diseases
Fibromusculardysplasia
Dissection
Vasospasm
Aneurysm & pseudoaneurysm
Arterio-venous fistula
Arteritis: Takayasu–Horton
Carotid body tumor
Idiopathic carotidynia
Most common cause

93. Fibromusculardysplasia
Middle age women –String of beads pattern
Alternating zones of vasoconstriction & vasodilation for 3 –5 cm
ICA frequently –VA less frequently
Usually bilateral
ICA

94. Dissection of aorta & cervical arteries
Patho-anatomy
Intimal rupture with false lumen
Open or secondarily thrombosed
Aorta
External intramural hematoma
Lumen constriction
Rare intimal rupture
Cervical

95. Spontaneous dissection of ICA
Asymmetric wall hematoma –Lumen stenosis –Expansion to outside
Diagnostic criteria (one sufficient)
Intramural hematoma
Intimal rupture/double lumen
Distal stenosis or occlusion
Symptoms: acute pain, Horner,
Course: recanalization in few weeks

96. Dissection of common carotid artery
Transverse view Longitudinal view
Detection of two lumina & dissection membrane

97. Vasospasm
Severe narrowing of ICA No stenosis detected
4 days later

98. Extra-cranial ICA aneurysms
Color Doppler US Power Doppler US
Incomplete delineation of aneurysm –Thrombi could not be excluded

99. Arterio-venous fistula
Attempt to perform US-guided jugular catheter insertion
Turbulent flow in fistula trackHigh-velocity turbulent flow in track
Suspicion of communication between CCA & IJV
CCA
IJV

100. Takayasu’sarteritis
Young female –SCA [‘pulseless’ disease] –CCA
CCA
Long hypoechoic wall thickening
Visualized in color Doppler as dark halo around vascular lumen

101. Horton's arteritis/ Giant cell arteritis
Concentric hypoechoicwall thickening
Superficial temporal artery
VA –Longitudinal view VA –Transverse view

102. Doppler US of carotid arteries
Anatomy of carotid arteries
Normal Doppler US of carotid arteries
Causes of carotid artery disease
Effect of extra-carotid diseases

103. Effect of extra-carotid diseases
•Idiopathic dilated cardiomyopathy
•Aortic regurgitation
•Aortic stenosis
•Stenosisof right innominateartery or
origin of LCCA
•Stenosisof intra-cranial ICA

104. Idiopathic dilated cardiomyopathy
Pulsusalternans
PSV oscillating between two levels on sequential beats
Cardiac rhythm remains regular throughout

105. Aortic regurgitation
Bisferiouswaveform[“beat twice” in Latin]
Two systolic peaks separated by midsystolic retraction
Dicrotic notch
Found also with hypertrophic obstructive cardiomyopathy

106. Severe aortic regurgitation
Normal or elevated PSV followed by precipitous decline
Revered flow during diastole
Water-hammer spectral appearance
CCA

107. Right inominate artery stenosis
RICA : to-and-fro flow
RCCA : to-and-fro flow
RVA : reversed flow
RSCA : damped flow
Right carotid steal

108. Thank You

109. Reference
•Diagnostic Ultrasound –4
th
edition
•Sonographic Examination of the Carotid
Arteries –Radiographics, 2005
•Anatomy of Diagnostic Radiology-Ryan
•Radiopedia