seminar on carotid Doppler

1. CAROTID DOPPLER
By – Dr. Aashish
Moderators – HOD sir & Dr. Rajeswari ma’am

2. ANATOMY
Major branches of arch of aorta:
 Innominate / brachiocephalic artery
 Left common carotid artery
 Left subclavian artery

4. ANATOMY
Right and left common carotid arteries lie postero-laterally
to thyroid gland and deep to internal jugular vein and
sternocleidomastoid.
Right CCA originates at the bifurcation of brachiocephalic
artery.
Left CCA originated directly from arch of aorta and can
also arise with brachiocephalic trunk – Bovine
configuration.

6. ANATOMY
At the carotid bifurcation
CCA
External Internal

7. CCA
The common carotid artery may be compressed against the
prominent transverse process of the sixth cervical vertebra
(carotid tubercle).
 Above this level the artery is superficial and its pulsation
can be readily felt beneath the anterior border of
sternocleidomastoid.

8. VARIATIONS IN BIFURCATION OF
CCA WITH RELATION TO CERVICAL
VERTEBRA

9. ICA
The internal carotid arteries and their major branches (the
internal carotid system or anterior circulation) supply blood
to the majority of the forebrain.
The internal carotid artery arises from the bifurcation of the
common carotid artery, ascends in the neck and enters the
carotid canal of the temporal bone. Its course contains
Cervical, Petrous, Lacerum, Cavernous, Clinoid,
Ophthalmic & Communicating segments.

10. BRANCHES OF INTERNAL
CAROTID
A: Anterior choroidal artery
V: Vidian artery
I: Inferolateral trunk
P: Posterior communicating artery
S: Superior hypophyseal artery
C: Caroticotympanic artery
O: Ophthalmic artery
M: Meningohypophyseal trunk
M: Middle cerebral artery
A: Anterior cerebral artery

11. BRANCHES OF EXTERNAL
CAROTID
S: superior thyroid artery Sister
L: lingual artery Louis
P: posterior auricular artery Powdered
F: facial artery Face
O: occipital artery Often
A: ascending pharyngeal artery Attracts
M: maxillary artery Medical
S: superficial temporal artery Students

12. SURFACE ANATOMY
In the neck, the common carotid artery and its continuation,
the internal carotid artery may be represented by a straight
line from the sternoclavicular joint to a point just behind the
condyle of the mandible.
At the level of the upper border of the thyroid cartilage
(approximately at a level between the third and fourth
cervical vertebrae) the common carotid artery divides into
the external and internal carotid arteries.

13. INTRODUCTION
Ultrasound assessment of carotid arterial atherosclerotic
disease has become the first choice for carotid
artery screening, permitting the evaluation of both the
macroscopic appearance of plaques as well as flow
characteristics in the carotid artery.

14. CAROTID DUPLEX
B-mode and Doppler.
B-mode – grey scale, visualization of structures and
assessment of plaque morphology.
 Hyperechoic
 Hypoechoic

15. CAROTID DUPLEX
Doppler
 Velocities: peak systolic and end diastolic.
 Estimate range of stenosis.
 Determine direction of blood flow.

16. INDICATIONS OF CAROTID
DOPPLER
Hemispheric neurologic symptoms
Stroke
Transient ischemic attack
Amaurosis fugax
Carotid bruit
Pulsatile neck masses

17. INDICATIONS
Patients scheduled for major cardiovascular surgery
Non-hemispheric / unexplained neurologic symptoms
Proven carotid disease
Carotid revascularization including stenting
Monitoring of vascular surgery
Suspected subclavian steal syndrome

18. INDICATIONS
Potential source of retinal emboli
Follow up of carotid dissection
Follow up of radiation therapy to neck

19. INSTRUMENTATION
High frequency (5MHz or above) transducers with short
focal distances designed for near field work.
Colour Doppler imaging.
Duplex ultrasound with angle correction capabilities.
Doppler spectral waveform analysis.
Power Doppler imaging to assess low flow states and
possible occlusions.

22. CAROTID ULTRASOUND
EXAMINATION
Supine position.
Neck slightly extended.
Head turned away from site being examined.
5-12 MHz transducer for grey-scale.
3-7 MHz transducer for Doppler sonography.
5-10 MHz transducer for power Doppler.

23. TRANSDUCER POSITION
Several positions are used to examine the artery in long
axis(longitudinal) planes.
Selective short axis(transverse) views of carotid are
obtained from anterior, lateral, posterolateral approach .
Postero-lateral approach ,most useful for bifurcation &
distal ICA. The patient’s head should be turned far to contra
lateral side and transducer placed posterior to
sternocleidomastoid .
In some cases, anterolateral approach works best.

24. PROTOCOL
Vessels should be imaged as completely as possible
Caudal angulation of the transducer in the supra clavicular
region and cephalic angulation at the level of the mandible
Assessed both in grey scale and colour doppler settings.
Starting from proximal most CCA, bulb, ECA and ICA.
Distal carotid 2 cm from the bulb

25. LIMITATIONS
Short muscular neck
High carotid bifurcation
Tortuous vessels
Calcified shadowing plaques

31. CAROTID ULTRASOUND
INTERPRETATION
In most cases the gray-scale, color Doppler, and power
Doppler sonographic images and assessments will agree.
Disagreement – discover its source.
Grey scale and colour Doppler images better demonstrate
and quantify low-grade stenosis.
High-grade occlusive disease – more accurately defined by
Doppler spectral pattern.

32. CAROTID ULTRASOUND
INTERPRETATION
Plaque assessment must be done only in grey-scale, without
colour or power Doppler.

33. ROLE OF POWER DOPPLER
Provides increased sensitivity to visualize the continuity of
blood flow in arterial stenosis.
Advantages:-
Angle independent
No aliasing
Very sensitive to low velocity and low amplitude flow
Helps in differentiating critical stenosis from occlusion

34. POWER DOPPLER
Disadvantages:-
motion sensitive
does not give direction and velocity of flow

35. EXTERNAL CAROTID
Systolic upstroke is sharp
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

37. INTERNAL CAROTID
Low‐resistance waveform pattern.
Systolic peak should be sharp and the spectral envelope
should be thin.
Continuous forward diastolic flow.
Systolic peak may be slightly blunter than the systolic peak
of the ECA.

39. COMMON CAROTID
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

41. CAROTID ULTRASOUND
ECA:
 Feeds high resistance vascular bed.
 Velocity rises sharply during systole.
 Falls quickly during diastole.

42. CAROTID USG
ICA:
 Feeds lower resistance brain circulation.
 Large quantities of flow continue during diastole.
 Velocity usually increase from proximal to distal.
CCA:
 Resembles ICA waveform.
 Diastolic flow above baseline.

45. CAROTID STENOSIS
Carotid artery stenosis also referred as extra cranial carotid
artery stenosis, is usually caused by an atherosclerotic
process and is one of the major causes
of stroke and transient ischemic attack (TIA).
The stenosis involving carotid bulb and the proximal
segment of ICA are the most common sites of
symptomatic and clinically relevant stenosis.

46. ABNORMAL CCA
either low or high PSVs.
abnormally high‐resistance waveform,
an abnormally low‐resistance waveform,

47. A normal CCA PSV should be in the range of 60 – 100 cm/s
IF less than this, examine opposite side
Symmetric ----------- > Low cardiac output
Asymmetric ------------ > Evaluate further
A velocity difference of >20 cm/sec between the right and left is
abnormal

48. OCCLUSION
Proximal stenosis (brachiocephalic)
Parvus ‐ tardus waveform or normal pattern but
asymmetrical PSVs.
Distal stenosis (carotid bulb level)
High resistance wave form

49. ICA
Normal
 ICA PSV is <125 cm/sec and no plaque or intimal thickening is
visible sonographically.
 Additional criteria include ICA/CCA PSV ratio <2.0 and
ICA EDV <40 cm/sec
<50% ICA stenosis
 ICA PSV is <125 cm/sec and plaque or intimal thickening is visible
sonographically.
 Additional criteria include ICA/CCA PSV ratio <2.0 and
ICA EDV <40 cm/sec

50. 50-69% ICA stenosis
 ICA PSV is 125-230 cm/sec and plaque is visible sonographically
 additional criteria include ICA/CCA PSV ratio of 2.0-4.0 and ICA
EDV of 40-100 cm/sec
≥70% ICA stenosis but less than near occlusion
 ICA PSV is >230 cm/sec and visible plaque and luminal narrowing
are seen at gray-scale and colour Doppler ultrasound
 additional criteria include ICA/CCA PSV ratio >4 and ICA
EDV >100 cm/sec

51. Near occlusion of the ICA
 Velocity parameters may not apply, since velocities may be high,
low, or undetectable.
 Diagnosis is established primarily by demonstrating a markedly
narrowed lumen at colour or power Doppler ultrasound.
Total occlusion of the ICA:
 No detectable patent lumen at gray-scale US and no flow with
spectral, power, and colour Doppler ultrasound.
 There may be compensatory increased velocity in the contra lateral
carotid.

53. PLAQUE CHARACTERIZATION
Atheromatous carotid plaques evaluated for:
 Extent
 Location
 Surface contour
 Texture
 Luminal stenosis

54. PLAQUE CHARACTERIZATION
Most common cause of TIA – embolism.
Important to identify low-grade atherosclerotic lesions
containing haemorrhage / ulceration.
Plaque – independent risk factor for developing stroke.
50-60 % of patients with hemispheric stroke symptoms
demonstrate hemorrhagic and ulcerated plaque.

55. PLAQUE TEXTURE
Homogenous plaque:
 Uniform echopattern
 Smooth surface
 Sonolucency < 50% of plaque volume
 Uniform acoustic texture corresponds to dense fibrous
connective tissue.
 More common – 80-85% cases.

57. PLAQUE TEXTURE
Heterogeneous plaque:
 Complex echopattern
 ≥ 1 focal sonolucent areas corresponding > 50% of
plaque volume.
 Contains intraplaque haemorrhage and deposits of
lipid, cholesterol and proteinaceous material.
Sensitivity – 90-94%
Specificity – 75-88%

58. PLAQUE MORPHOLOGY BASED
ON ULTRASOUND
Type 1 Predominantly echolucent
with thin echogenic cap.
Type 2 Substantially echolucent with
small areas of echogenicity
(>50% sonolucent).
Type 3 Predominantly echogenic
with small areas of
echoluceny (<50%
sonolucent).
Type 4 Uniformly echogenic.

59. TYPE 1 & 2 PLAQUES
Similar to heterogeneous plaque.
More likely to be associated with intraplaque haemorrhage
with ulceration.
Unstable and subject to abrupt changes in size after
haemorrhage / embolization.
Typically in symptomatic patients with stenosis > 70 % of
diameter.

62. TYPE 3 & 4 PLAQUES
Similar to homogeneous plaque.
Benign and stable.
Composed of fibrous tissue and calcification.
Typically seen in asymptomatic patients.

65. PLAQUE ULCERATION
All ulcerated plaques which can be accurately identified fit
into heterogeneous pattern.
USG findings:
 Focal depression or break in plaque surface.
 Anechoic region within plaque extending to vessel lumen.
 Eddies of colour within plaque.

69. POTENTIAL PITFALL IN
DIAGNOSIS
Mirror imaging artefact producing pseudo-ulceration of
carotid artery.
Highly reflective plaque can produce color doppler ghost
artefact simulating ulceration.
Region of color within the plaque can be recognised as
artefactual.

70. PITFALLS IN DIAGNOSIS
Spectral waveform and color shading within the pseudo-
ulceration are of lower amplitude, but otherwise identical to
those within the true carotid lumen.
Pulsed Doppler traces from within ulcer craters show low-
velocity damped waveforms.

71. VERTEBRALARTERY
Variations in origin are common.
Usually first branch of subclavian artery.
6-8 % - directly from the aortic arch.
90% - proximal vertebral artery ascends superomedially,
entering transverse foramen at C6 level.

72. VERTEBRALARTERY
42% - left larger than right.
26% - equal size on both sides.
32% - right larger than left.
Join at their confluence to form the basilar artery.

74. VERTEBRALARTERY
Supplies majority of posterior circulation of brain.
Collateral circulation to other parts in carotid occlusive
disease.
Has a low resistance flow pattern similar to CCA with
continuous systole and diastole.
Because of small size, flow tends to demonstrate broader
spectrum.

75. SEGMENTS OF VERTEBRAL
ARTERY
V1 (preforaminal)
V2 (foraminal)
V3 (atlantic, extradural or extraspinal)
V4 (intradural or intracranial).

77. VERTEBRAL WAVEFORM
Low resistance wave pattern
Forward diastolic flow
No systolic or diastolic notch
Similar to carotid in flow (colour)
No reversal of wave form

79. ABNORMAL VERTEBRAL
ARTERY WAVEFORMS

80. SUBCLAVIAN STEAL SYNDROME
Occurs when there is high grade stenosis or occlusion of the
proximal subclavian or innominate arteries with patent
vertebral arteries bilaterally.
Artery of ischemic limb steals blood from vertebrobasilar
circulation through retrograde vertebral artery flow, which
amy result in symptoms of vertebrobasilar insufficiency.

83. SUBCLAVIAN STEAL SYNDROME
Symptoms more pronounced during exercise of upper
extremity.
Also known as subclavian steal steno-occlusive disease.

84. SUBCLAVIAN STEAL SYNDROME
Causes include:
 Atherosclerotic disease (most common)
 Traumatic
 Embolic
 Surgical
 Congenital
 Neoplastic

85. STAGES
Reduced anterograde vertebral flow (stage I)
Reversal of flow during reactive hyperemia testing of the
arm (stage II)
Permanent retrograde vertebral flow (stage III).

86. INCOMPLETE/PARTIAL
SUBCLAVIAN STEAL
Transient reversal of vertebral artery flow during systole.
Maybe converted to complete steal using provocative
manoeuvres.
Suggestive of high grade stenotic lesion of subclavian
artery rather than occlusion.

88. INCOMPLETE SUBCLAVIAN
STEAL
Provocative manoeuvres such as exercising the arm for 5
minutes or 5 minute inflation of sphygmomanometer on the
arm to induce rebound hyperaemia on the side of subclavian
lesion can enhance sonographic findings and convert an
incomplete steal to complete.

90. PRESTEAL PHENOMENON
Anterograde flow but with a striking deceleration of
velocity in peak systole to a level less than EDV.
In patients with proximal subclavian stenosis.
Can be converted to partial or complete steal waveform by
provocative manoeuvres.

91. TARDUS-PARVUS WAVEFORM
Damped waveform.
In patients with high grade proximal vertebral artery
stenosis.

92. STENOSIS AND OCCLUSION
Most hemodynamically significant stenosis occurs at
vertebral artery origin.
Accurate velocity measurement difficult because of deep
location and tortuosity.
Velocities > 100 cm/s often indicate stenosis.

93. STENOSIS AND OCCLUSION
Focal increase in velocity of at least 50% visible stenosis or
striking tardus-parvus waveform indicates significant
vertebral stenosis.

94. THANK YOU