Carotid Artery Doppler : A case based approach

1. CAROTID ARTERY DOPPLER:
A CASE BASED APPROACH
Dr. Anamika Gupta

2.  A 60 year old male patient, Mr I S, presented with chief complaint of:
 Giddiness and vertigo x 1 mth
 No h/ o Loss of consiousness
 No h/o TIA/FND
 Past h/o k/co HTN – 15 Yrs
 h/o 1 e/o chest pain a/w diaphoresis, gabrahat – 6 mth back , ECG- T wave inversion in 11,
111, aVF
 Where 2 D ECHO- CAD- RWMA- mid basal IW, IVS – HK, LVEF 45%
 CAG Showed – LM (d)– 60-70%, ostialLAD- 95% , ostial LCX-100%, m RCA ( ND)- 100%,
collaterals from LAD – LCX
 CABG- LIMA- LAD, RSVG to PDA
 No sig family history
 Personal h/o – chronic smoker
 Vitals: BP – 160/90 mm of Hg, PR- 64/ min
 B/L Carotid Bruit with
 Distal pulses palpable in all 4 extremities.
 2D Echo: Normal LV systolic function

3.  ?B/L Carotid artery disease
 ?posterior circulation abnormality
 F/U Essential HTN
 F/U CABG for CAD- USAP- TVD –NSR- N LV
function- NYHA I

4. WHAT IS Carotid Doppler study
 B-mode analysis
 Color doppler analysis
 Doppler frequency spectrum analysis

5. Color doppler analysis
 It shows the direction of blood flow relative to transducer.
 Normally red is towards the transducer and blue is away.
 A shift in color from red to orange or from blue to green
represents increase in flow velocity.
 Color and pulse doppler shows close to 100% sensitivity
and specificity in the near occlusion of the ICA.
 The pulsed doppler is more sensitive than color doppler for
the detection of slow or low velocity flow. Highly damped
arterial flow can be mistaken for venous flow(can be
confirmed by flow detection)

6. Doppler spectrum analysis
 Doppler spectrum is the graphic representation of the
mixture of frequencies present in a small area of vessel
over a short period of time.
 Blood flow produces a mixture of doppler frequency
shift that changes from moment to moment and place
to place within the vessel lumen.
 It is useful in identifying of-
- pulsatility of vessel by doppler waveform
- pattern of flow (laminar or disturbed flow)
- quantitive measurement of vascular index

7. Time is represented along the horizontal axis, and frequency shift (velocity) is
depicted along the vertical axis.
The width of the spectral line represents the range of velocities within a vessel.
The width may vary during the normal cardiac cycle, narrowing during systole
and widening in diastole.
The spectral window is the clear black zone between the spectral line and the
baseline. Widening of the spectral line and filling of the spectral window is
called spectral broadening. Spectral broadening is normally seen in the
presence of high flow velocity, at the branching of a vessel, or in small-diameter
vessels.

8. Laminar and disturbed flow
 Laminar flow: in arteries blood flow in center of
vessel move faster than blood at periphery. This is
called laminar as movement of blood is in parallel
lines.
In this majority of blood cells move at uniform speed
in sample volume. Doppler spectrum shows thin line
that outlines a clear space called spectral window.

9.  Disturbed flow : movement of blood is less
uniform and orderly than in laminar flow. Doppler
spectrum shows spectral broadening or widening
of spectral waveform.
Broadening { severity of flow disturbance}
-It often indicates vascular disease.
-may occur in normal vessels at kinks, curves,
arterial branching e.g. at carotid bulb.
-may occur spuriously when large sample volume
encompasses both the slow flow near the vessel
wall and rapid flow at the vessel center.

10. Pulsatility
Low pulsatility:-(low resistance vessel)
 waveforms have broad systolic peaks and forward flow
throughout the diastole.
 This is also called monophasic b/c flow is always forward
and entire waveform is either above or below the
transducer .
 These vessels feed the circulatory system with low
resistance to flow .
 e.g. carotid a.(CCA, ICA ), vertebral a.,celiac a. renal a.
-Broad systolic peak
-continuous forward
diastolic flow
-monophasic waveform

11. Moderate pulsatility :
- have waveform patterns b/w low resistance and high
resistance pattern.
- systolic peak is tall and sharp, forward flow is
present throughout diastole.
e.g. ECA, SMA(during fasting).

12. High pulsatility:-
 waveforms have tall, narrow, sharp systolic peak and
reversal or absent distolic flow.
 These vessels feed the circulatory system with high
resistance to flow.
 Classic example is triphasic flow pattern seen in
extremity artery.
 It has three phases: 1stphase-systolic peak
2ndphase-brief flow reversal
3rdphase-brief forward flow

13. INDICATIONS FOR CAROTID ULTRASOUND
 Evaluation of patient with transient ischemic
attack,cerebrovascular accident
 Evaluation of carotid bruits
 Follow up of known disease
 Monitor endarterectomy /stents results
 Preoperative screen prior to major vascular surgery
 Evaluation of potential source of retinal emboli
 Evaluation of pulsatile neck mass
 Follow up of carotid dissection

14. Position for scanning the carotid arteries
Thrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.
Elsevier Churchill Livingstone, London, 2nd edition, 2005.
•Patient lie down in supine or semi supine
position .Head hyperextended & rotated 45°
away from side being examined can be
varied for better visualization
•Higher frequency linear transducer(>7MHz)
are ideal for assessment of intima media
thickness and plaque morphology
•Lower frequency transducer <7MHz
preferred for doppler examination

15. Longitudinal scan to visualize carotid arteries
Anterior
Posterior
Lateral

16.  Begin each scan on same side, usually the right
 Avoid excess pressure on carotid bifurcation to avoid
– Stimulate carotid sinus Bradycardia
Syncope
Ventricular asystole
– Compress arteries to cause spurious high velocities
Myers KA & Clough A. Making sense of vascular ultrasound. Arnold, London, 2004.

17. EXAMINATION SEQUENCE
Step 1–Anterior/ postero-lateral approach – carotid vessels in
longitudinal view
Step 2–record a velocity spectrum in CCA. Following points
to be noted –
i. Measurement point 4 cm below carotid bulb
ii. Sample vol is squarely within the center of vessel
iii. Doppler angle < 60°
Step 3–survey the carotid bifurcation with color flow imaging
Step 4 – confirm the identity of ICA and ECA
Step 5 – scrutinize significant areas of plaque formation
Step 6 – record vel at stenotic area

18. Step 1 CAROTID ART VS JUGULAR VEIN
FEATURES CAROTID ART JUGULAR VEIN
Flow Towards head
and pulsatile
Towards feet and
typical venous
Caliber Fairly uniform Varies markedly
from moment to
moment/resp.
Wall Thick, distinct
intimal reflection
Thin, collapse on
pressure

19. STEP- 2 ACCURATE VELOCITY MEASUREMENT
 PSV increases about 9cm for each centimeter of distance
as we proceed proximally from the carotid bifurcation.
 So the recommendation to measure CCA velocity at a
standardized distance—4cm below the carotid
bifurcation.

20. High cardiac output: Hypertensive patients
Young athletes
High flow > 125 cm/sec in both CCAs
Poor cardiac output: Cardiomyopathies
Valvular heart disease
Extensive MI
Low flow < 45 cm/sec in both CCAs
Tahmasebpour HR et al. RadioGraphics 2005 ; 25 : 1561 – 1575.
Normal PSV in CCA (45 – 125 cm/sec)

21. Typical normal Doppler spectra
Common carotid artery
Internal carotid artery
External carotid artery
Zwiebel WL. Introduction to vascular ultrasonography.
W.B. Saunders, Philadelphia, USA, 4th edition, 2000.
PSV: 45 – 125 cm/sec
Difference between 2 sides < 15 cm/sec
PSV in ECA<100 cm/sec
PSV in CCA < 100 cm/sec

22. DOPPLER SPECTRUM AND VELOCITIES
RIGHT CCA LEFT CCA

23. DOPPLER SPECTRUM AND VELOCITIES
RIGHT ICA

24. DOPPLER SPECTRUM AND VELOCITIES
RIGHT ECA LEFT ECA

25. STEP- 3 Carotid bifurcation
Longitudinal B-mode image of carotid bifurcation
ICA & ECA seen in same plane
Thrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.
Elsevier Churchill Livingstone, London, 2nd edition, 2005.

26. RIGHT CCA BRANCHING AND BULB

27. STEP -4 Differentiation between ICA & ECA
Features ICA ECA
 Size Usually larger Usually smaller
 Temporal tap Usually negative Usually positive
 Pulsed
Doppler
Low resistance High resistance
 Orientation Posterior towards
mastoid
Anterior towards face
 Branches Rarely Yes

28. USG Assessment of carotid plaque
 Atherosclerotic plaque - revealed sonographically by an increase
in combined thickness of intima and media layers and
subsequently by echogenic material that encroaches on the
arterial lumen.
 The normal CIMT increases linearly with the age from a mean of
0.48 at age 40yrs to 1.02 at age 100 yrs and follows the
formula- (0.009*age)+0.116
 Intima –Media thickness of 0.9mm or more is abnormal and
likely to be associated with sonographically visible plaque.
 Extent - length of vessel affected by plaque
 Severity - thickness of plaque – best measure from transverse
images

29. Intima-Media complex
Normal value ≤ 0.8 mm
Myers KA & Clough A. Making sense of vascular ultrasound. Arnold, London, 2004.
Wall of CCA, bulb, or ICA
Best measured on far wall
Only intima & media included

30. RIGHT CCA CIMT

31. Plaque characterization
 The plaque can be characterized as low medium or high in
echogenicity or as homogenous or heterogeneous in
texture.
 Low echogenicity:- Fibrofatty plaque – containing large
amount of lipid material
 less echogenic than nearby sternomastoid muscle.
 US-difficulty overcomed with color flow or B flow imaging
because flow void is visible even if plaque is not well seen
 less cellular than more echogenic plaque
 associated with elevated serum level of LDL, plaque
ulceration and increased risk of cerebral ischemic
symptoms.

32. Moderate echogenicity:- As the collagen and
cellular content of plaque increases relative to the fat
content;echogenicity also increases.
 Its echogenicity equals or exceeds that of sternomastoid
muscle but is less echogenic than arterial adventitia.
 It is less associated with cerebral ischemic symptoms
than low echogenic plaque or heterogeneous plaque.
Strong echogenicity:- Dystrophic calcification occurs
in plaque and generates strong reflections accompnied by
distal acoustic shadows.
 Plaque calcification may be focal or diffuse and large
calcifications generates acoustic shadows that obscures the
arterial lumen interfering with the usg diagnosis.
 Calcified areas represents healed or dormant process ;
no immediate threat to fibrous cap or endothelium.

33. Appearance of atheromatous plaques
Homogeneous echolucent Homogeneous echogenic
Myers KA & Clough A. Making sense of vascular ultrasound. Arnold, London, 2004.
Heterogeneous plaque Cauliflower’ calcification

34. RIGHT CCA PLAQUE LEFT CCA PLAQUE
RYT CCA

36. Carotid plaque typeType Characteristics
Risk of symptoms
1. Uniformly echolucent
2. Predominantly Echolucent
(>50% of plaque structure)
3. Predominantly Echogenic
(>50% of plaque structure)
4. Uniformly Echogenic
5. unclassified due to calcification
or poor visualization.
 High
 High
 Lower
 Lowest
 Unknown

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

38. Assessment of carotid stenosis
Cardinal Doppler parameter to grade stenosis
Best documented Doppler parameter for carotid stenosis
Peak Systolic Velocity (PSV)
Quite valuable for detecting high-grade carotid stenosis
End Diastolic Velocity (EDV)
Avoid errors of collateralization
Avoid errors of physiological factors:
BP – Pulse rate – Cardiac output – Peripheral resistance
PSV ratio

39. PRE –STENOTIC AREA
 Majority of cases carotid stenosis or occlusion
occurs in the proximal ICA.
 If there is very high grade carotid stenosis or ICA
occlusion outflow is primarily through the high
resistance external carotid circulation.
 Under such circumstances the CCA waveform takes on
the high flow resistance characteristics of an ECA with
flow to zero or nearly zero in end diastole
 The CCA contralateral to an ICA stenosis or occlusion
may demonstrate increased flow velocity overall with
particular elevation of the EDV represents a
compensatory increase in blood flow volume in the
non obstructed ICA in response to reduced cerebral
perfusion.

40. Stenotic area
Locating the stenotic region:-the presence
of color shifts indicating high velocity flow and color
mosaics indicating poststenotic turbulence aid in
selecting potential areas for examination with the pulsed
doppler.
 As stenosis develops the PSV first becomes elevated
therefore PSV is a principal measure of stenosis
severity.
 EDV lags behind relatively but as stenosis progresses it
rises rapidly as stenosis becomes severe (diameter
reduction of >60%). The EDV is a good marker of high
grade stenosis.

41. Post stenotic area
 Damping of doppler velocity waveform is seen in the region
distal to carotid stenosis when the lesion is severe and flow
reducing.
1.Systolic acceleration is slowed
2.systolic peak is rounded
3.maximal systolic velocity is lower than normal
4.Diastolic flow is increased.
 Post-stenotic flow disturbance with spectral broadening found
in the area immediately distal to stenotic site.
 This waveform also called pulsus parvus-means overall low
velocity and pulsus tardus-means delayed arrival of systolic
peak.

42. POST STENOTIC

43. Pseudo-spectral broadening
 High gain setting
 Vessel wall motion
 Tortuous vessels
 Site of branching
 Abrupt change in vessel diameter
 ↑ velocity: athlete - high cardiac output - AVF1 -
AVM2
 Aneurysm, dissection, & FMD3
1AVF: Arterio-Venous Fistula
2AVM: Arterio-Venous Malformation
3FMD: Fibro-Muscular Dysplasia

44. Post-stenotic zone / Distal to site of
stenosis
Rohren EM et al. Am J Roentgenol 2003 ; 181 : 1695 – 1704.
Tardus-parvus waveform

45. Temporal tap maneuver

46. Abropoulos NL et al. Vasc Endovascular Surg 2007 ; 41 : 417 – 427.
Temporal tapping of ECA
“Saw-tooth” appearance
Small regular deflections (TT)
Frequency corresponds to rate of temporal tapping
Deflections best seen during diastole

47. Temporal tap
Internal & external carotid artery findings
ICA
temporal tap
ECA
temporal tap
Normal + / − +
Significant ICA stenosis − +
Significant ECA
stenosis
+ −
Robbin ML et al. Ultrasound Clin 2006 ; 1 : 111 – 131.

48. LEFT ECA TEMPORAL TAP
INCREASED VELOCITY

49. LEFT CCA EXTERNALISATION
TEMPORAL TAP

50. LEFT CCA EXTERNALISATION

52. Grading Carotid Artery stenosis
 Various factors that contributes to the clinical importance of a carotid
plaque are plaque composition, hemorrhage, ulceration the status of
fibrous cap overlying the plaque and severity of luminal reduction.
 Of these only severity of stenosis has been unequivocally demonstrated
to predict stroke.
 Sensitivity and specificity for doppler USG for detecting an ICA stenosis of
50% to 99% or greater are b/w 90% and 95%
 Normally the CCA has attributes of the ICA and ECA, the CCA will take on
the quality of the normal vessel (ICA or ECA) when the other is occluded.

53. Degree of ICA Stenosis in Doppler US*
Consensus Criteria(Society of radiologists in ultrasound)
ICA stenosis ICA PSV ICA EDV PSV ratio
(%) cm/sec cm/sec ICA/CCA
Normal < 125 < 40 < 2.0
< 50% < 125 < 40 < 2.0
50 – 69% 125 – 230 40 – 100 2.0 – 4.0
> 70% > 230 > 100 > 4.0
Near occlusion variable variable variable
Total occlusion detectable undetectable not applicable
* Diameter reduction
Grant EG et al. Radiology 2003 ; 229 : 340 – 346.

54. Stenosis of ECA
 PSV of ECA stenosis Minimal < 200 cm/sec
Moderate 200 – 300
cm/sec
Severe > 300 cm/sec
 ECA/CCA systolic ratio* < 2 ≤ 50% Ø stenosis
≥ 2 ≥ 70% Ø stenosis
* Päivänsalo MJ et al. Acta Radiologica 1996 ; 37 : 41 – 43.
Isolated ECA stenosis not clinically significant

55. FINAL INTERPRETATION
RYT LEFT
CCA PSV 127/36 111/ 25
ICA – PSV/ EDV 308/100
ECA 71.7 445/96
ICA/CCA PSV RATIO 2.4

56.  IN our case, there is significant stenosis of Right
ICA(70-99%), left ECA, and Left ICA seems to be
completely occluded.

62. THANKS

65. Occlusion of CCA
Tahmasebpour HR et al. RadioGraphics 2005 ; 25 : 1561 – 1575.
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

66. Occlusion of ICA
 Absence of flow by color, power & pulsed Doppler
 “Internalization” of ipsilateral ECA waveform
 Reversed flow in ICA or CCA proximal to occlusion
 Thrombus or plaque completely fills lumen of ICA
 Externalization of ipsilateral CCA or proximal ICA
 Higher velocities in controlateral CCA

67. 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

68.  Occluded vessel is irremediable whereas a nearly
occluded vessel may be treated with CEA if the
stenosis is localised and the distal vessel is good
caliber.(so the differentiation b/n these two is
important)
 A nearly occluded ICA often produces the
angiographic string sign.
 String sign result from pudding of the slow moving
contrast agent in the dependant portion of the arterial
lumen.

70. Diagnosis of idiopathic carotidynia
International Headache Society (IHS)1
 At least one of following over CA: Tenderness
Swelling
Increased pulsations
 Pain over affected side of neck that may project to head
 Appropriate investigations without structural abnormality
Recent publications demonstrate radiological
findings2
 Self-limiting syndrome of less than 2 weeks duration
1 International Headache Society. Cephalalgia 1988 ; 8 (Suppl 7) : 1 – 96.
2 Kosaka N et al. Eur Radiol 2007 ; 17 : 2430 – 2433.

71. Idiopathic carotidynia
US findings comparable to dissection
Kosaka N et al. Eur Radiol 2007 ; 17 : 2430 – 2433.
Enhanced tissue
around carotid artery
CE T1-weighted MRIUS of distal CCA
Hypo-echoic soft tissue
around carotid artery
Three months later
Resolution of abnormal
soft tissue

72. Spontaneous dissection & carotidynia
Spontaneous dissection Carotidynia
Location Beyoud bifurcation At or near bifurcation
Thickening layers One wall layer 2 wall layers
Stenosis May be detectable Not detectable
Pain Head Neck
MRI Native enhancement Enhancement after CAs
In unclear cases, MRI enables differentiation
Arning C et al. Ultraschall Med 2008 ; 29 : 576 – 599.

73. 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
Degree of stenosis indeterminate
Other modalities recommended

74. Carotid body tumor / Rare
Histology Paraganglioma of low malignant potential
Presentation Palpable neck mass – Headache – Neck pain
US Highly vascular mass in carotid bifurcation
Arteriography Performed preoperatively – Embolization
Treatment Resection to prevent local adverse events:
Laryngeal nerve palsy – carcinoma invasion
Result Local recurrence 6% – Distant metastasis 2%

75. Carotid body tumor
Highly vascular mass in carotid bifurcation
Zwiebel WL. Introduction to vascular ultrasonography.
W.B. Saunders, Philadelphia, USA, 4th edition, 2000.

76. Effect of extra-carotid diseases
 Idiopathic dilated cardiomyopathy
 Aortic regurgitation
 Aortic stenosis
 Stenosis of right innominate artery or origin of
LCCA
 High & low PSV in CCA
 Stenosis of intra-cranial ICA

77. Idiopathic dilated cardiomyopathy
Pulsus alternans
Rohren EM et al. Am J Roentgenol 2003 ; 181 : 1695 – 1704.
PSV oscillating between two levels on sequential beats
Cardiac rhythm remains regular throughout

78. Aortic regurgitation
Bisferious waveform [“beat twice” in Latin]
Kallman CE et al. Am J Roentgenol 1991 ; 157 : 403 – 407.
Rohren EM et al. AJR 2003 ; 181 : 169 5– 1704.
Two systolic peaks separated by midsystolic retraction
Dicrotic notch
Found also with hypertrophic obstructive cardiomyopathy

79. Aortic stenosis
Scoutta LM et al. Ultrasound Clin 2006 ; 1 : 133 – 159.
RCCA – Tardus-Parvus LCCA – Tardus-Parvus
RVA – Tardus-Parvus

80. Right inominate artery stenosis
Zwiebel WJ, Pellerito JS. Introduction to Vascular Ultrasonography.
5th ed. Philadelphia: Elsevier Saunders; 2005.
RICA : to-and-frow flow
RCCA : to-and-frow flow
RVA : reversed flow
RSCA : damped flow
Right carotid steal

81. ICA
High-grade stenosis distally (intracranial ICA)
Major occlusive lesions of cerebral arteries (MCA, ACA)
Massive spasm of cerebral arteries from intracranial hemorrhage
Stenosis of intra-cranial ICA
High resistance waveform
Abropoulos NL et al. Vasc Endovascular Surg 2007 ; 41 : 417 – 427.

82.  Internal carotid artery(ICA):-Anterior circulation to brain. In cervical
region it may be straight or curve tortuously as it travel to the base of
skull. There are no branches of ICA in the neck.
 Intracranial branches-
 1.carotympanic branches in petrous bone.
 2.menigohypophyseal branches in cavernous sinus region.
 3.Posrerior communicating arteries –eight millimeter beyond clinoid
process which anastomoses with PCA(br of VA).
 4.Finally it divides into Anterior carotid artery(ACA), Middle carotid
artery(MCA), Anterior choroidal artery and Ophthalmic A.
 External carotid artery(ECA):-normally supplies no blood to brain. It is
medial to ICA. Branches of ECA -1)ascending pharangeal 2)superior
thyroid 3)lingual A. 4)Maxillary A. 5)OccipitalA. 6)facial A.
7)Superficial temporal.