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Principles of Doppler ultrasound Samir Haffar M.D. Department of Internal Medicine
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Page 1: Principles of Doppler ultrasound

Principles of Doppler ultrasound

Samir Haffar M.D.Department of Internal Medicine

Page 2: Principles of Doppler ultrasound

General principles

Spectral-specific parameters

Color-specific parameters

Power Doppler imaging

Normal flow in arteries

Normal flow in veins

Principles of Doppler ultrasound

Page 3: Principles of Doppler ultrasound

General principles of Doppler ultrasound

Page 4: Principles of Doppler ultrasound

Christian Doppler (1803 – 1853) Famous for what is called now the “Doppler effect”

1841 Professor of mathematics & physics Prague polytechnic

1842 Published his famous book “On the colored light of the binary stars & some other stars of the heavens”

1850 Head of institute of experimental physics Vienna University

Austrian physicist

Page 5: Principles of Doppler ultrasound

The Doppler effectProposed by Christian Doppler in 1842

• Change in frequency of a wave for an observer movingrelative to the source of the wave

• Commonly heard when a vehicle sounding a sirenapproaches, passes, & recedes from an observer

• Received frequency Higher during approachIdentical at instant of passing byLower during recession

Page 6: Principles of Doppler ultrasound

What is the Doppler phenomenon?

Thrush A, Hartshorne T. Peripheral vascular ultrasound: how, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.

= ft

> ft

= ft

< ft

Page 7: Principles of Doppler ultrasound

What is the Doppler phenomenon?

Doppler shift frequency (fd): ft – fr

Thrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.

ft

fr

Page 8: Principles of Doppler ultrasound

Doppler equation

∆ F Doppler shift frequency (kHz)

F0 Ultrasound transmission frequency (MHz)

V Blood cell velocity (cm/sec)

Cos ӨCos of angle between US & flow direction

C Speed of sound in soft tissue (1 540 m/sec)

∆ F = 2 F0 V Cos Ө / C

Page 9: Principles of Doppler ultrasound

Goals of Doppler

• Detection flow in a vessel

• Detection direction of flow

• Detection type of flow: Arterial or venous Normal or

abnormal

• Measurement the velocity of flow

Page 10: Principles of Doppler ultrasound

Types of Doppler

Continuous wave Doppler

Spectral Doppler (duplex)

Spectral & color Doppler (triplex)

Power Doppler

Page 11: Principles of Doppler ultrasound

All Doppler ultrasound examinations shouldbe performed with:

Tahmasebpour HR et al. RadioGraphics 2005 ; 25 : 1561 – 1575.

• Gray-scale US

• Color Doppler

• Spectral Doppler

• Power Doppler

Page 12: Principles of Doppler ultrasound

Spectral-specific parameters

Page 13: Principles of Doppler ultrasound

Spectral Doppler

Angle correctioncursor

Beam path

Sample volume

Baseline

EDV

Thrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.

PSV

Page 14: Principles of Doppler ultrasound

Doppler shift frequency & angle of insonation

Thrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.

Page 15: Principles of Doppler ultrasound

Use of spectral baseline

Normal baseline

Inverted baseline

Dropping baseline

Page 16: Principles of Doppler ultrasound

Sample volume length

Large sample volume lengthSmall sample volume length

Thrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.

Page 17: Principles of Doppler ultrasound

Optimizing gate size & position

Kruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.

Wide gate including PV (above baseline) & HV (below baseline)

Gate should be positioned over central part of the studied vessel

Page 18: Principles of Doppler ultrasound

Doppler equation

∆ F Doppler shift frequency (kHz)

F0 Ultrasound transmission frequency (MHz)

V Blood cell velocity (cm/sec)

Cos ӨCos of angle between US & flow direction

C Speed of sound in soft tissue (1 540 m/sec)

∆ F = 2 F0 V Cos Ө / C

Page 19: Principles of Doppler ultrasound

Percentage error in velocity measurements & angle of insonation

In order to minimize this error,angles of insonation > 60% should not be used

Page 20: Principles of Doppler ultrasound

Optimizing Doppler angle Larger the angle, greater the error

• Ideally should be zero Usually not possible • Smallest angle possible Not under our control• Do not use angle > 60° Great error in velocity• Angle 90° Complete loss of flow

• Transducer position Obtain smaller angle

• Different US systems May be different results

Thrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.

Page 21: Principles of Doppler ultrasound

Doppler angle measurement

Angle: 60°PSV: 110 cm/secEDV: 41 cm/sec

Angle: 44°PSV: 74 cm/secEDV: 27 cm/sec

Thrush A et al. Peripheral vascular ultrasound. Elsevier Churchill Livingstone, London, 2005.

Page 22: Principles of Doppler ultrasound

Changing position of the transducer

IntercostalTransabdominal Subcostal

Kruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.

Page 23: Principles of Doppler ultrasound

Adjusting spectral velocity scale

Spectral scale: 200 cm/sec Spectral scale: 50 cm/sec

Kruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.

Color Doppler image, color bar, & color scale unchanged Spectral component is active

Page 24: Principles of Doppler ultrasound

Adjusting spectral Doppler gain Gain setting 0% Gain setting 38%

Gain setting 77% Gain setting 100%

Kruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.

Page 25: Principles of Doppler ultrasound

Spectral wall filter

Wall filter 75 Hz

Wall thump removed

Wall filter 550 Hz

Filter frequency too high

Altered waveform

Wall filter 50 Hz

Wall thump

Thrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.

Page 26: Principles of Doppler ultrasound

Spectral aliasing CCA

Dropping baseline Increasing scalePeaks cross baseline

Rubens DJ et al. Doppler artifacts & pitfalls. Ultrasound Clin 2006 ; 1 : 79 – 109.

Page 27: Principles of Doppler ultrasound

Color-specific parameters

Page 28: Principles of Doppler ultrasound

Color map

BaselineWall filter

Page 29: Principles of Doppler ultrasound

Changing color baseline

Kruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.

When color baseline changed → color velocity range changed

Range of depicted velocities remains constant

Page 30: Principles of Doppler ultrasound

Examples of different color maps

Thrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.

Velocity range(cm/sec)

Inversion ofcolor map

Color writepriority

Baselinewall filter

Page 31: Principles of Doppler ultrasound

Inversion of color flow

Kruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.

Reversal of this inversionAppropriate directional flow noted

Portal venous flow appears blueFalsely suggests flow reversal

Page 32: Principles of Doppler ultrasound

Inversion of spectral flow

Kruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.

Page 33: Principles of Doppler ultrasound

Color box size / Overlay

Kruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.

Oversized color box↑ frame rate & ↓ resolution

Reduced color box size↓ frame rate & ↑ resolution

Color box should be as small & superficial as possible

Page 34: Principles of Doppler ultrasound

Doppler angle effects

Thrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.

Page 35: Principles of Doppler ultrasound

Color box steeringChanging angle of insonation

Large angleUnusable image

Small angleGood image

Moderate angleFlow is not optimal

Steered either left or right by a maximum of 20 – 25° Sensitivity of transducer decreases as beam is steered

Thrush A et al. Peripheral vascular ultrasound. Elsevier Churchill Livingstone, 2nd edition, 2005.

Page 36: Principles of Doppler ultrasound

Color box steered in more than one direction to demonstrate flow in the whole vessel

Color box steering

Thrush A et al. Peripheral vascular ultrasound. Elsevier Churchill Livingstone, 2nd edition, 2005.

Page 37: Principles of Doppler ultrasound

Adjusting color velocity scale

Kruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.

Color velocity scale 2 cm/secColor aliasing in PV & its branches

High color velocity scale (69 cm/sec)Apparent absence of flow in PV

Color velocity scale 30 cm/sec Normal flow in a patent PV

Page 38: Principles of Doppler ultrasound

Color Doppler aliasing

Velocity scale range 12 cm/sec Velocity scale range 23 cm/sec

Rubens DJ et al. Doppler artifacts & pitfalls. Ultrasound Clin 2006 ; 1 : 79 – 109.

Page 39: Principles of Doppler ultrasound

Portal vein pseudo-clot

Velocity scale: 20 cm/s Velocity scale: 7 cm/s

Page 40: Principles of Doppler ultrasound

Adjusting color gain

Kruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.

Color gain should be set as high as possible without displaying random color speckles

Color gain 44% Color gain 65% Color gain 100%

Page 41: Principles of Doppler ultrasound

Adjusting color gain

Flow ‘bleeding out’ of the vesselColor gain set too high

Thrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.

Page 42: Principles of Doppler ultrasound

Adjusting color wall filter

Filter setting displayed on color scale (horizontal arrow)

Filter too high Removing low flow

Filter setting reduced Display low flow

Thrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.

Page 43: Principles of Doppler ultrasound

Pseudo-thrombosis of main PV Adjusting velocity & angle of insonation

Velocity: 24 cm/secWall filter: medium

Angle 90°

Velocity: 7 cm/secWall filter: medium

Angle < 90°

Radiol Clin N Am 2006 ; 44 : 805 – 835.

Page 44: Principles of Doppler ultrasound

Doppler panel on console of many contemporary US imagers

Each parameter can be adjusted to optimize spectral or

color Doppler components of the examination

Kruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.

Page 45: Principles of Doppler ultrasound

Clinical & tissue-specific presets

• Clinical option GeneralAdultObstetric (etc…)

• Tissue-specific preset AbdomenRenalTransplant (etc...)

Kruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.

Once a transducer selected

preset choices includes:

Page 46: Principles of Doppler ultrasound

Guidelines for optimal Doppler examination

Adjust gain & filter

Adjust velocity scale & baseline

Doppler angle < 60° by steering & probe position

Color box as small & superficial as possible

Sample volume size: 2/3 of vessel width in the center

Avoid transducer motion

Rubens DJ et al. Doppler artifacts & pitfalls. Ultrasound Clin 2006 ; 1 : 79 – 109.

Page 47: Principles of Doppler ultrasound

Power Doppler imaging

Page 48: Principles of Doppler ultrasound

Advantages of power mode Doppler

• No aliasing

• Angle independent

• Increased sensitivity to detect low-velocity flow Distinguish pre-occlusive from occlusive lesionsSuperior depiction of plaque surface morphology

• Useful in imaging tortuous vessels

• Increases accuracy of grading stenosis

Page 49: Principles of Doppler ultrasound

Power Doppler imaging

Large plaque ulcerICA

Narrow flow channel in ICA“string sign” or “trickle flow ”

Page 50: Principles of Doppler ultrasound

Disadvantages of power Doppler imaging

• Do not provide velocity of flow

• Do not provide direction of flowNew machines provide direction of flow in power mode

• Very motion sensitive (poor temporal resolution)Less suitable for rapid scan along vessels

Page 51: Principles of Doppler ultrasound

Normal flow in arteries & veins

Page 52: Principles of Doppler ultrasound

Flow at a curvature & bifurcation

Myers KA & Clough A. Making sense of vascular ultrasound. Arnold, London, 2004.

Apex of parabola moves away from concave wall at a curve

Apex of parabola moves away from outer wall at bifurcation

Page 53: Principles of Doppler ultrasound

Flow around curves in a vessel

Tortuous ICA

Thrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.

A B

A

PSV outside the bend 70 cm/sec

B

PSV inside the bend 55 cm/sec

Page 54: Principles of Doppler ultrasound

Normal flow reversal zone in ICA

Opposite to origin of the ECAHigh velocities near flow divider

Reversal on opposite side to flow divider

Thrush A et al. Peripheral vascular ultrasound. Elsevier Churchill Livingstone, London, 2005.

Page 55: Principles of Doppler ultrasound

High & low resistance arterial flow

High-resistance flowSFA

Low-resistance flowICA

Myers KA & Clough A. Making sense of vascular ultrasound. Arnold, London, 2004.

Page 56: Principles of Doppler ultrasound

Arterial high resistance flow

Typical normal Doppler spectra

Normal anterior tibial arteryTriphasic flow

Page 57: Principles of Doppler ultrasound

Pulsatility index

Most commonly used of all indices

S Systolic

D Minimum diastolic

M Mean

PI S – D / M

Page 58: Principles of Doppler ultrasound

Effect of exercise on flow

Dorsalis Pedis Artery at restTriphasic flow

Thrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.

DPA following exerciseMonophasic hyperemic flow

Page 59: Principles of Doppler ultrasound

Arterial monophasic flow

• HyperemicExercise Infection Temporary arterial occlusion by blood pressure cuff

• Distal to severe stenosis or occlusion Low velocity Longer rise time* Tardus-Parvus wave

* Rise time: time between beginning of systole & peak systole

Page 60: Principles of Doppler ultrasound

Tardus-Parvus waveDistal to severe stenosis or occlusion

Thrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.

Tardus: Longer rise time

Parvus: Low PSV

Page 61: Principles of Doppler ultrasound

Arterial low resistance flowTypical normal Doppler spectra

Normal internal carotid artery

Page 62: Principles of Doppler ultrasound

Pourcelot’s resistance index

RI S – ED / S

Normal 50 – 70 %

Abnormal > 80 %

Page 63: Principles of Doppler ultrasound

Accleration Time (AT) or Rise Time (RT)

• Length of time in seconds from

onset of systole to peak systole

• Normal value: ≤ 0.07 second

Page 64: Principles of Doppler ultrasound

Acceleration index

AI = X (KHz)

Probe frequency (MHz)

Normal value: > 3.8 cm/s2

Page 65: Principles of Doppler ultrasound

Aacleration time & PSV

Early systolic pick

AJR - Dec 1995

Biphasic with late systolic pick

Monophasic with late systolic pick

Page 66: Principles of Doppler ultrasound

AT & AI according to degree of stenosis

Moderate stenosis 50 – 85%

Normal Severe stenosis> 85 %

Page 67: Principles of Doppler ultrasound

Measurement of volume flow

Volume = Cross-sectional area × Mean velocity × 60 (ml/min) (cm2) (cm/sec)

Cross-sectional area (cm2): π d2 / 4d: diameter

Page 68: Principles of Doppler ultrasound

Doppler equationConverting Doppler shift frequency to velocity

∆ F Doppler shift frequency (kHz)

F0 Ultrasound transmission frequency (MHz)

V Blood cell velocity (cm/sec)

Cos ӨCos of angle between US & flow direction

C Speed of sound in soft tissue (1 540 m/sec)

∆ F = 2 F0 V Cos Ө / C

Page 69: Principles of Doppler ultrasound

∆ F

F0

V ?

Cos Ө

C

∆ F = 2 F0 V Cos Ө / C

50 cm/s

1.6 kHz

5 MHz

60°

1 540 m/sec

Thrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.

Doppler equationConverting Doppler shift frequency to velocity

Page 70: Principles of Doppler ultrasound

Blood flow & PSV changes relatedto severity of arterial stenosis

Myers KA & Clough A. Making sense of vascular ultrasound. Arnold, London, 2004.

Page 71: Principles of Doppler ultrasound

Flow through a stenosis

Thrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.

Increased velocity through stenosis Flow reversal beyond stenosis

CCA

IJV

ICA

Color from red to turquoise Posterior wall – deep blue

Page 72: Principles of Doppler ultrasound

Pic Systolic Velocity ratio

Robbin ML et al. Ultrasound Clin 2006 ; 1 : 111 – 131.

Proximal: 2 cm proximal to stenosis

Same Doppler angle if possible

Page 73: Principles of Doppler ultrasound

Post-stenotic zone/Spectral broadeningProportional to severity of stenosis

• Cannot be precisely quantified (evaluated visually)Fill-in of spectral window > 50% diameter reductionSeverely disturbed flow > 70% diameter reduction

High amplitude & low frequency signalLow amplitude & high frequency signalFlow reversal – Poor definition of spectral

border

• May be only sign of stenosis: calcified plaque

Page 74: Principles of Doppler ultrasound

Spectral broadeningImmediate post-stenotic zone

Page 75: Principles of Doppler ultrasound

Pseudospectral broadening

• High gain setting

• Vessel wall motion

• Site of branching

• Abrupt change in vessel diameter

• ↑ velocity: athlete, high cardiac output, AVF1, & AVM2

• Tortuous vessels

• Aneurysm, dissection, & FMD3

1AVF: Arterio-Venous Fistula2AVM: Arterio-Venous Malformation3FMD: Fibro-Muscular Dysplasia

Page 76: Principles of Doppler ultrasound

Color Doppler bruit

Extensive soft tisuue color Doppler bruit surrounds

the carotid bifurcation with 90% ICA stenosis

Page 77: Principles of Doppler ultrasound

Venous valve

Two cups of a valve clearly seenIt is uncommon to see venous valves with this clarity

Page 78: Principles of Doppler ultrasound

Normal venous flow

Spontaneity Spontaneous flow without augmentation

Phasicity Flow changes with respiration

Compression Transverse plane

Augmentation Compression distal to site of examination Patency below site of examination

Valsalva Deep breath, strain while holding breath Patency of abdominal & pelvic veins

Page 79: Principles of Doppler ultrasound

Normal venous flow

Spontaneity Spontaneous flow without augmentation

Phasicity Flow changes with respiration

Compression Transverse plane

Augmentation Compression distal to site of examination Patency below site of examination

Valsalva Deep breath, strain while holding breath Patency of abdominal & pelvic veins

Page 80: Principles of Doppler ultrasound

Phasicity

Flow changes with respiration

Slow ApneaRapid

Page 81: Principles of Doppler ultrasound

Normal venous flow

Spontaneity Spontaneous flow without augmentation

Phasicity Flow changes with respiration

Compression Transverse plane

Augmentation Compression distal to site of examination Patency below site of examination

Valsalva Deep breath, strain while holding breath Patency of abdominal & pelvic veins

Page 82: Principles of Doppler ultrasound

Compressibility of veins

Do not press too hard since the normal vein collapsesvery easily making it difficult to find

11

Page 83: Principles of Doppler ultrasound

Incompressibility = Thrombus

Do not compress vein more than necessary in recent thrombusFear of detaching thrombus to cause PE

Myers KA & Clough A. Making sense of vascular ultrasound. Arnold, London, 2004.

Page 84: Principles of Doppler ultrasound

External compression of the vein

Relaxation Compression

A

Page 85: Principles of Doppler ultrasound

Normal venous flow

Spontaneity Spontaneous flow without augmentation

Phasicity Flow changes with respiration

Compression Transverse plane

Augmentation Compression distal to site of examination Patency below site of examination

Valsalva Deep breath, strain while holding breath Patency of abdominal & pelvic veins

Page 86: Principles of Doppler ultrasound

Augmented flow in popliteal vein

Aug Competent vein

Page 87: Principles of Doppler ultrasound

Normal venous flow

Spontaneity Spontaneous flow without augmentation

Phasicity Flow changes with respiration

Compression Transverse plane

Augmentation Compression distal to site of examination Patency below site of examination

Valsalva Deep breath, strain while holding breath Patency of abdominal & pelvic veins

Page 88: Principles of Doppler ultrasound

Valsalva’s maneuver

Valsalva’s maneuver

A V

Normal respiration

A V

Page 89: Principles of Doppler ultrasound

Valsalva maneuver

Start Valsalva

End Valsalva

Competent vein

Page 90: Principles of Doppler ultrasound

Indicate on the report whether

the examination was excellent, good or poor

Emphasize if a scan is suboptimal

Myers KA & Clough A. Making sense of vascular ultrasound. Arnold, London, 2004.

Page 91: Principles of Doppler ultrasound

References

Arnold – 2004 Elsevier – 2005 Elsevier Mosby – 2005

Page 92: Principles of Doppler ultrasound

Thank You