Principles of Doppler ultrasoundSamir Haffar M.D.Department of Internal Medicine
 General principles Spectral-specific parameters Color-specific parameters Power Doppler imaging Normal flow in arter...
 General principles of Doppler ultrasound
Christian Doppler (1803 – 1853)Famous for what is called now the “Doppler effect”1841 Professor of mathematics & physicsPr...
The Doppler effectProposed by Christian Doppler in 1842• Change in frequency of a wave for an observer movingrelative to t...
What is the Doppler phenomenon?Thrush A, Hartshorne T. Peripheral vascular ultrasound: how, why and when.Elsevier Churchil...
What is the Doppler phenomenon?Doppler shift frequency (fd): ft – frThrush A, Hartshorne T. Peripheral vascular ultrasound...
Doppler equation∆ F Doppler shift frequency (kHz)F0 Ultrasound transmission frequency (MHz)V Blood cell velocity (cm/sec)C...
Goals of Doppler• Detection flow in a vessel• Detection direction of flow• Detection type of flow: Arterial or venousNorma...
Types of Doppler Continuous wave Doppler Spectral Doppler (duplex) Spectral & color Doppler (triplex) Power Doppler
All Doppler ultrasound examinations shouldbe performed with:Tahmasebpour HR et al. RadioGraphics 2005 ; 25 : 1561 – 1575.•...
 Spectral-specific parameters
Spectral DopplerAngle correctioncursorBeam pathSample volumeBaselineEDVThrush A, Hartshorne T. Peripheral vascular ultraso...
Doppler shift frequency & angle of insonationThrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Els...
Use of spectral baselineNormal baselineInverted baselineDropping baseline
Sample volume lengthLarge sample volume lengthSmall sample volume lengthThrush A, Hartshorne T. Peripheral vascular ultras...
Optimizing gate size & positionKruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.Wide gate including PV (above baseline...
Doppler equation∆ F Doppler shift frequency (kHz)F0 Ultrasound transmission frequency (MHz)V Blood cell velocity (cm/sec)C...
Percentage error in velocity measurements& angle of insonationIn order to minimize this error,angles of insonation > 60% s...
Optimizing Doppler angleLarger the angle, greater the error• Ideally should be zero Usually not possible• Smallest angle p...
Doppler angle measurementAngle: 60PSV: 110 cm/secEDV: 41 cm/secAngle: 44PSV: 74 cm/secEDV: 27 cm/secThrush A et al. Periph...
Changing position of the transducerIntercostalTransabdominal SubcostalKruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.
Adjusting spectral velocity scaleSpectral scale: 200 cm/sec Spectral scale: 50 cm/secKruskal JB et al.RadioGraphics 2004 ;...
Adjusting spectral Doppler gainGain setting 0% Gain setting 38%Gain setting 77% Gain setting 100%Kruskal JB et al.RadioGra...
Spectral wall filterWall filter 75 HzWall thump removedWall filter 550 HzFilter frequency too highAltered waveformWall fil...
Spectral aliasingCCADropping baseline Increasing scalePeaks cross baselineRubens DJ et al. Doppler artifacts & pitfalls.Ul...
 Color-specific parameters
Color mapBaselineWall filter
Changing color baselineKruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.When color baseline changed → color velocity r...
Examples of different color mapsThrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchi...
Inversion of color flowKruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.Reversal of this inversionAppropriate directio...
Inversion of spectral flowKruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.
Color box size / OverlayKruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.Oversized color box↑ frame rate & ↓ resolutio...
Doppler angle effectsThrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingst...
Color box steeringChanging angle of insonationLarge angleUnusable imageSmall angleGood imageModerate angleFlow is not opti...
Color box steered in more than one direction todemonstrate flow in the whole vesselColor box steeringThrush A et al. Perip...
Adjusting color velocity scaleKruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.Color velocity scale 2 cm/secColor alia...
Color Doppler aliasingVelocity scale range 12 cm/sec Velocity scale range 23 cm/secRubens DJ et al. Doppler artifacts & pi...
Portal vein pseudo-clotVelocity scale: 20 cm/s Velocity scale: 7 cm/s
Adjusting color gainKruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.Color gain should be set as high as possiblewitho...
Adjusting color gainFlow „bleeding out‟ of the vesselColor gain set too highThrush A, Hartshorne T. Peripheral vascular ul...
Adjusting color wall filterFilter setting displayed on color scale (horizontal arrow)Filter too highRemoving low flowFilte...
Pseudo-thrombosis of main PVAdjusting velocity & angle of insonationVelocity: 24 cm/secWall filter: mediumAngle 90Velocity...
Doppler panel on console of manycontemporary US imagersEach parameter can be adjusted to optimize spectral orcolor Doppler...
Clinical & tissue-specific presets• Clinical option GeneralAdultObstetric (etc…)• Tissue-specific preset AbdomenRenalTrans...
Guidelines for optimal Doppler examination Adjust gain & filter Adjust velocity scale & baseline Doppler angle < 60 by ...
 Power Doppler imaging
Advantages of power mode Doppler• No aliasing• Angle independent• Increased sensitivity to detect low-velocity flowDisting...
Power Doppler imagingLarge plaque ulcerICANarrow flow channel in ICA“string sign” or “trickle flow ”
Disadvantages of power Doppler imaging• Do not provide velocity of flow• Do not provide direction of flowNew machines prov...
 Normal flow in arteries & veins
Flow at a curvature & bifurcationMyers KA & Clough A. Making sense of vascular ultrasound. Arnold, London, 2004.Apex of pa...
Flow around curves in a vesselTortuous ICAThrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevi...
Normal flow reversal zone in ICAOpposite to origin of the ECAHigh velocities near flow dividerReversal on opposite side to...
High & low resistance arterial flowHigh-resistance flowSFALow-resistance flowICAMyers KA & Clough A. Making sense of vascu...
Arterial high resistance flowTypical normal Doppler spectraNormal anterior tibial arteryTriphasic flow
Pulsatility indexMost commonly used of all indicesS SystolicD Minimum diastolicM MeanPI S – D / M
Effect of exercise on flowDorsalis Pedis Artery at restTriphasic flowThrush A, Hartshorne T. Peripheral vascular ultrasoun...
Arterial monophasic flow• HyperemicExerciseInfectionTemporary arterial occlusion by blood pressure cuff• Distal to severe ...
Tardus-Parvus waveDistal to severe stenosis or occlusionThrush A, Hartshorne T. Peripheral vascular ultrasound: How, why a...
Arterial low resistance flowTypical normal Doppler spectraNormal internal carotid artery
Pourcelot’s resistance indexRI S – ED / SNormal 50 – 70 %Abnormal > 80 %
Accleration Time (AT)or Rise Time (RT)• Length of time in seconds fromonset of systole to peak systole• Normal value: ≤ 0....
Acceleration indexAI =X (KHz)Probe frequency (MHz)Normal value: > 3.8 cm/s2
Aacleration time & PSVEarly systolic pickAJR - Dec 1995Biphasic with late systolic pickMonophasic with late systolic pick
AT & AI according to degree of stenosisModerate stenosis50 – 85%Normal Severe stenosis> 85 %
Measurement of volume flowVolume = Cross-sectional area Mean velocity 60(ml/min) (cm2) (cm/sec)Cross-sectional area (cm2):...
Doppler equationConverting Doppler shift frequency to velocity∆ F Doppler shift frequency (kHz)F0 Ultrasound transmission ...
∆ FF0V ?Cos ӨC∆ F = 2 F0 V Cos Ө / C50 cm/s1.6 kHz5 MHz601 540 m/secThrush A, Hartshorne T. Peripheral vascular ultrasound...
Blood flow & PSV changes relatedto severity of arterial stenosisMyers KA & Clough A. Making sense of vascular ultrasound. ...
Flow through a stenosisThrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Living...
Pic Systolic Velocity ratioRobbin ML et al. Ultrasound Clin 2006 ; 1 : 111 – 131.Proximal: 2 cm proximal to stenosisSame D...
Post-stenotic zone/Spectral broadeningProportional to severity of stenosis• Cannot be precisely quantified (evaluated visu...
Spectral broadeningImmediate post-stenotic zone
Pseudospectral broadening• High gain setting• Vessel wall motion• Site of branching• Abrupt change in vessel diameter• ↑ v...
Color Doppler bruitExtensive soft tisuue color Doppler bruit surroundsthe carotid bifurcation with 90% ICA stenosis
Venous valveTwo cups of a valve clearly seenIt is uncommon to see venous valves with this clarity
Normal venous flow Spontaneity Spontaneous flow without augmentation Phasicity Flow changes with respiration Compressio...
Normal venous flow Spontaneity Spontaneous flow without augmentation Phasicity Flow changes with respiration Compressio...
PhasicityFlow changes with respirationSlow ApneaRapid
Normal venous flow Spontaneity Spontaneous flow without augmentation Phasicity Flow changes with respiration Compressio...
Compressibility of veinsDo not press too hard since the normal vein collapsesvery easily making it difficult to find11
Incompressibility = ThrombusDo not compress vein more than necessary in recent thrombusFear of detaching thrombus to cause...
External compression of the veinRelaxation CompressionA
Normal venous flow Spontaneity Spontaneous flow without augmentation Phasicity Flow changes with respiration Compressio...
Augmented flow in popliteal veinAug Competent vein
Normal venous flow Spontaneity Spontaneous flow without augmentation Phasicity Flow changes with respiration Compressio...
Valsalva’s maneuverValsalva’s maneuverA VNormal respirationA V
Valsalva maneuverStartValsalvaEndValsalvaCompetent vein
Indicate on the report whetherthe examination was excellent, good or poorEmphasize if a scan is suboptimalMyers KA & Cloug...
ReferencesArnold – 2004 Elsevier – 2005 Elsevier Mosby – 2005
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Principles of Doppler ultrasound

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  • Ө (theta), also referred to as the Doppler angle,is the angle between the transmitted beam and the direction ofblood flow within the blood vessel (the reflector path). Converting Doppler shift frequencies to velocity measurements.
  • Ө (theta), also referred to as the Doppler angle,is the angle between the transmitted beam and the direction ofblood flow within the blood vessel (the reflector path). Converting Doppler shift frequencies to velocity measurements.
  • The larger the angle of insonation, the greater the potential source of error in velocity measurement.
  • Because each pixel is displayed either as gray-scale or color, increasing the color priority will permit color information to be displayed where low-intensity signals may be present, such as at the periphery of vessels. Alternatively, increasing the gray-scale priority will result in grayscale information being depicted and displacingcolor data. Depending on the manufacturer, many US imagers permit adjustment of the color priority on a scale that is often depicted adjacent to the color bar.
  • The frame rate is the rate per second at which complete images are produced.With pulse-echo imaging alone, the frame rate can exceed 50 images per second.However, the time required to produce color flow images is much longer, which significantly lowers the frame rate. The frame rate in color imaging is dependent on several factors.For example, the size and position of the color box have a great effect on the frame rate. The width of the box is especially important: The wider the box, the more scan lines are required and the longer it will taketo acquire the data to produce the image.
  • Arrow shows position of posterior artery wall
  • Tardus: slowed systolic accelerationParvus: low-amplitude systolic peak
  • AI: acceleration index Systolic upslope/transducer frequency (cm/s2)
  • Doppler spectrum showing the measurement of PSV &amp; EDV.Mean velocity can be calculated from the Doppler spectrum, displayed by the black line. A large sample volume allow the blood velocity at anterior and posterior walls, as well as in center of the vessel, to be estimated but may not detect the flow along the lateral wall. Time-averaged mean velocity (TAM) can be found by averaging the mean velocity over one or more complete cardiac cycles. Volume flow can be calculated by multiplying the TAM measurement by the cross-sectional area of the vessel.Reference:Thrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.
  • Ө (theta), also referred to as the Doppler angle,is the angle between the transmitted beam and the direction ofblood flow within the blood vessel (the reflector path). Converting Doppler shift frequencies to velocity measurements.
  • Ө (theta), also referred to as the Doppler angle,is the angle between the transmitted beam and the direction ofblood flow within the blood vessel (the reflector path). Converting Doppler shift frequencies to velocity measurements.
  • Turbulence in an artery causes its wall to vibrate and this produces a noise propagated through tissues that can be heard with a stethoscope or seen on an ultrasound scan.It may require an increase in velocity by exercising to reduce peripheral resistance to cause sufficient turbulence to allow a bruit to be heard.
  • Principles of Doppler ultrasound

    1. 1. Principles of Doppler ultrasoundSamir Haffar M.D.Department of Internal Medicine
    2. 2.  General principles Spectral-specific parameters Color-specific parameters Power Doppler imaging Normal flow in arteries Normal flow in veinsPrinciples of Doppler ultrasound
    3. 3.  General principles of Doppler ultrasound
    4. 4. Christian Doppler (1803 – 1853)Famous for what is called now the “Doppler effect”1841 Professor of mathematics & physicsPrague polytechnic1842 Published his famous book“On the colored light of the binary stars& some other stars of the heavens”1850 Head of institute of experimental physicsVienna UniversityAustrian physicist
    5. 5. 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
    6. 6. 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
    7. 7. What is the Doppler phenomenon?Doppler shift frequency (fd): ft – frThrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.ftfr
    8. 8. Doppler equation∆ F Doppler shift frequency (kHz)F0 Ultrasound transmission frequency (MHz)V Blood cell velocity (cm/sec)Cos Ө Cos of angle between US & flow directionC Speed of sound in soft tissue (1 540 m/sec)∆ F = 2 F0 V Cos Ө / C
    9. 9. Goals of Doppler• Detection flow in a vessel• Detection direction of flow• Detection type of flow: Arterial or venousNormal or abnormal• Measurement the velocity of flow
    10. 10. Types of Doppler Continuous wave Doppler Spectral Doppler (duplex) Spectral & color Doppler (triplex) Power Doppler
    11. 11. 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
    12. 12.  Spectral-specific parameters
    13. 13. Spectral DopplerAngle correctioncursorBeam pathSample volumeBaselineEDVThrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.PSV
    14. 14. Doppler shift frequency & angle of insonationThrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.
    15. 15. Use of spectral baselineNormal baselineInverted baselineDropping baseline
    16. 16. Sample volume lengthLarge sample volume lengthSmall sample volume lengthThrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.
    17. 17. Optimizing gate size & positionKruskal 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
    18. 18. Doppler equation∆ F Doppler shift frequency (kHz)F0 Ultrasound transmission frequency (MHz)V Blood cell velocity (cm/sec)Cos Ө Cos of angle between US & flow directionC Speed of sound in soft tissue (1 540 m/sec)∆ F = 2 F0 V Cos Ө / C
    19. 19. Percentage error in velocity measurements& angle of insonationIn order to minimize this error,angles of insonation > 60% should not be used
    20. 20. Optimizing Doppler angleLarger 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 resultsThrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.
    21. 21. Doppler angle measurementAngle: 60PSV: 110 cm/secEDV: 41 cm/secAngle: 44PSV: 74 cm/secEDV: 27 cm/secThrush A et al. Peripheral vascular ultrasound. Elsevier Churchill Livingstone, London, 2005.
    22. 22. Changing position of the transducerIntercostalTransabdominal SubcostalKruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.
    23. 23. Adjusting spectral velocity scaleSpectral scale: 200 cm/sec Spectral scale: 50 cm/secKruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.Color Doppler image, color bar, & color scale unchangedSpectral component is active
    24. 24. Adjusting spectral Doppler gainGain setting 0% Gain setting 38%Gain setting 77% Gain setting 100%Kruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.
    25. 25. Spectral wall filterWall filter 75 HzWall thump removedWall filter 550 HzFilter frequency too highAltered waveformWall filter 50 HzWall thumpThrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.
    26. 26. Spectral aliasingCCADropping baseline Increasing scalePeaks cross baselineRubens DJ et al. Doppler artifacts & pitfalls.Ultrasound Clin 2006 ; 1 : 79 – 109.
    27. 27.  Color-specific parameters
    28. 28. Color mapBaselineWall filter
    29. 29. Changing color baselineKruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.When color baseline changed → color velocity range changedRange of depicted velocities remains constant
    30. 30. Examples of different color mapsThrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.Velocity range(cm/sec)Inversion ofcolor mapColor writepriorityBaselinewall filter
    31. 31. Inversion of color flowKruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.Reversal of this inversionAppropriate directional flow notedPortal venous flow appears blueFalsely suggests flow reversal
    32. 32. Inversion of spectral flowKruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.
    33. 33. Color box size / OverlayKruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.Oversized color box↑ frame rate & ↓ resolutionReduced color box size↓ frame rate & ↑ resolutionColor box should be as small & superficial as possible
    34. 34. Doppler angle effectsThrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.
    35. 35. Color box steeringChanging angle of insonationLarge angleUnusable imageSmall angleGood imageModerate angleFlow is not optimalSteered either left or right by a maximum of 20 – 25Sensitivity of transducer decreases as beam is steeredThrush A et al. Peripheral vascular ultrasound. Elsevier Churchill Livingstone, 2nd edition, 2005.
    36. 36. Color box steered in more than one direction todemonstrate flow in the whole vesselColor box steeringThrush A et al. Peripheral vascular ultrasound. Elsevier Churchill Livingstone, 2nd edition, 2005.
    37. 37. Adjusting color velocity scaleKruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.Color velocity scale 2 cm/secColor aliasing in PV & its branchesHigh color velocity scale (69 cm/sec)Apparent absence of flow in PVColor velocity scale 30 cm/secNormal flow in a patent PV
    38. 38. Color Doppler aliasingVelocity scale range 12 cm/sec Velocity scale range 23 cm/secRubens DJ et al. Doppler artifacts & pitfalls.Ultrasound Clin 2006 ; 1 : 79 – 109.
    39. 39. Portal vein pseudo-clotVelocity scale: 20 cm/s Velocity scale: 7 cm/s
    40. 40. Adjusting color gainKruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.Color gain should be set as high as possiblewithout displaying random color specklesColor gain 44% Color gain 65% Color gain 100%
    41. 41. Adjusting color gainFlow „bleeding out‟ of the vesselColor gain set too highThrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.
    42. 42. Adjusting color wall filterFilter setting displayed on color scale (horizontal arrow)Filter too highRemoving low flowFilter setting reducedDisplay low flowThrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.
    43. 43. Pseudo-thrombosis of main PVAdjusting velocity & angle of insonationVelocity: 24 cm/secWall filter: mediumAngle 90Velocity: 7 cm/secWall filter: mediumAngle < 90Radiol Clin N Am 2006 ; 44 : 805 – 835.
    44. 44. Doppler panel on console of manycontemporary US imagersEach parameter can be adjusted to optimize spectral orcolor Doppler components of the examinationKruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.
    45. 45. 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 selectedpreset choices includes:
    46. 46. 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 motionRubens DJ et al. Doppler artifacts & pitfalls.Ultrasound Clin 2006 ; 1 : 79 – 109.
    47. 47.  Power Doppler imaging
    48. 48. Advantages of power mode Doppler• No aliasing• Angle independent• Increased sensitivity to detect low-velocity flowDistinguish pre-occlusive from occlusive lesionsSuperior depiction of plaque surface morphology• Useful in imaging tortuous vessels• Increases accuracy of grading stenosis
    49. 49. Power Doppler imagingLarge plaque ulcerICANarrow flow channel in ICA“string sign” or “trickle flow ”
    50. 50. 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
    51. 51.  Normal flow in arteries & veins
    52. 52. Flow at a curvature & bifurcationMyers KA & Clough A. Making sense of vascular ultrasound. Arnold, London, 2004.Apex of parabola moves awayfrom concave wall at a curveApex of parabola moves awayfrom outer wall at bifurcation
    53. 53. Flow around curves in a vesselTortuous ICAThrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.A BAPSV outside the bend 70 cm/secBPSV inside the bend 55 cm/sec
    54. 54. Normal flow reversal zone in ICAOpposite to origin of the ECAHigh velocities near flow dividerReversal on opposite side to flow dividerThrush A et al. Peripheral vascular ultrasound. Elsevier Churchill Livingstone, London, 2005.
    55. 55. High & low resistance arterial flowHigh-resistance flowSFALow-resistance flowICAMyers KA & Clough A. Making sense of vascular ultrasound. Arnold, London, 2004.
    56. 56. Arterial high resistance flowTypical normal Doppler spectraNormal anterior tibial arteryTriphasic flow
    57. 57. Pulsatility indexMost commonly used of all indicesS SystolicD Minimum diastolicM MeanPI S – D / M
    58. 58. Effect of exercise on flowDorsalis Pedis Artery at restTriphasic flowThrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.DPA following exerciseMonophasic hyperemic flow
    59. 59. Arterial monophasic flow• HyperemicExerciseInfectionTemporary arterial occlusion by blood pressure cuff• Distal to severe stenosis or occlusionLow velocityLonger rise time*Tardus-Parvus wave* Rise time: time between beginning of systole & peak systole
    60. 60. Tardus-Parvus waveDistal to severe stenosis or occlusionThrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.Tardus: Longer rise timeParvus: Low PSV
    61. 61. Arterial low resistance flowTypical normal Doppler spectraNormal internal carotid artery
    62. 62. Pourcelot’s resistance indexRI S – ED / SNormal 50 – 70 %Abnormal > 80 %
    63. 63. Accleration Time (AT)or Rise Time (RT)• Length of time in seconds fromonset of systole to peak systole• Normal value: ≤ 0.07 second
    64. 64. Acceleration indexAI =X (KHz)Probe frequency (MHz)Normal value: > 3.8 cm/s2
    65. 65. Aacleration time & PSVEarly systolic pickAJR - Dec 1995Biphasic with late systolic pickMonophasic with late systolic pick
    66. 66. AT & AI according to degree of stenosisModerate stenosis50 – 85%Normal Severe stenosis> 85 %
    67. 67. Measurement of volume flowVolume = Cross-sectional area Mean velocity 60(ml/min) (cm2) (cm/sec)Cross-sectional area (cm2): π d2 / 4d: diameter
    68. 68. Doppler equationConverting Doppler shift frequency to velocity∆ F Doppler shift frequency (kHz)F0 Ultrasound transmission frequency (MHz)V Blood cell velocity (cm/sec)Cos Ө Cos of angle between US & flow directionC Speed of sound in soft tissue (1 540 m/sec)∆ F = 2 F0 V Cos Ө / C
    69. 69. ∆ FF0V ?Cos ӨC∆ F = 2 F0 V Cos Ө / C50 cm/s1.6 kHz5 MHz601 540 m/secThrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.Doppler equationConverting Doppler shift frequency to velocity
    70. 70. Blood flow & PSV changes relatedto severity of arterial stenosisMyers KA & Clough A. Making sense of vascular ultrasound. Arnold, London, 2004.
    71. 71. Flow through a stenosisThrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.Elsevier Churchill Livingstone, London, 2nd edition, 2005.Increased velocity through stenosisFlow reversal beyond stenosisCCAIJVICA Color from red to turquoise Posterior wall – deep blue
    72. 72. Pic Systolic Velocity ratioRobbin ML et al. Ultrasound Clin 2006 ; 1 : 111 – 131.Proximal: 2 cm proximal to stenosisSame Doppler angle if possible
    73. 73. 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 reductionHigh amplitude & low frequency signalLow amplitude & high frequency signalFlow reversal – Poor definition of spectral border• May be only sign of stenosis: calcified plaque
    74. 74. Spectral broadeningImmediate post-stenotic zone
    75. 75. 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, & FMD31AVF: Arterio-Venous Fistula2AVM: Arterio-Venous Malformation3FMD: Fibro-Muscular Dysplasia
    76. 76. Color Doppler bruitExtensive soft tisuue color Doppler bruit surroundsthe carotid bifurcation with 90% ICA stenosis
    77. 77. Venous valveTwo cups of a valve clearly seenIt is uncommon to see venous valves with this clarity
    78. 78. Normal venous flow Spontaneity Spontaneous flow without augmentation Phasicity Flow changes with respiration Compression Transverse plane Augmentation Compression distal to site of examinationPatency below site of examination Valsalva Deep breath, strain while holding breathPatency of abdominal & pelvic veins
    79. 79. Normal venous flow Spontaneity Spontaneous flow without augmentation Phasicity Flow changes with respiration Compression Transverse plane Augmentation Compression distal to site of examinationPatency below site of examination Valsalva Deep breath, strain while holding breathPatency of abdominal & pelvic veins
    80. 80. PhasicityFlow changes with respirationSlow ApneaRapid
    81. 81. Normal venous flow Spontaneity Spontaneous flow without augmentation Phasicity Flow changes with respiration Compression Transverse plane Augmentation Compression distal to site of examinationPatency below site of examination Valsalva Deep breath, strain while holding breathPatency of abdominal & pelvic veins
    82. 82. Compressibility of veinsDo not press too hard since the normal vein collapsesvery easily making it difficult to find11
    83. 83. Incompressibility = ThrombusDo not compress vein more than necessary in recent thrombusFear of detaching thrombus to cause PEMyers KA & Clough A. Making sense of vascular ultrasound. Arnold, London, 2004.
    84. 84. External compression of the veinRelaxation CompressionA
    85. 85. Normal venous flow Spontaneity Spontaneous flow without augmentation Phasicity Flow changes with respiration Compression Transverse plane Augmentation Compression distal to site of examinationPatency below site of examination Valsalva Deep breath, strain while holding breathPatency of abdominal & pelvic veins
    86. 86. Augmented flow in popliteal veinAug Competent vein
    87. 87. Normal venous flow Spontaneity Spontaneous flow without augmentation Phasicity Flow changes with respiration Compression Transverse plane Augmentation Compression distal to site of examinationPatency below site of examination Valsalva Deep breath, strain while holding breathPatency of abdominal & pelvic veins
    88. 88. Valsalva’s maneuverValsalva’s maneuverA VNormal respirationA V
    89. 89. Valsalva maneuverStartValsalvaEndValsalvaCompetent vein
    90. 90. Indicate on the report whetherthe examination was excellent, good or poorEmphasize if a scan is suboptimalMyers KA & Clough A. Making sense of vascular ultrasound. Arnold, London, 2004.
    91. 91. ReferencesArnold – 2004 Elsevier – 2005 Elsevier Mosby – 2005
    92. 92. Thank You

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