2. General principles
Spectral-specific parameters
Color-specific parameters
Power Doppler imaging
Normal flow in arteries
Normal flow in veins
Principles of Doppler ultrasound
4. 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
5. The Doppler effect
Proposed by Christian Doppler in 1842
• Change in frequency of a wave for an observer moving
relative to the source of the wave
• Commonly heard when a vehicle sounding a siren
approaches, passes, & recedes from an observer
• Received frequency Higher during approach
Identical at instant of passing by
Lower during recession
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. 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
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 direction
C Speed of sound in soft tissue (1 540 m/sec)
∆ F = 2 F0 V Cos Ө / C
9. 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
10. Types of Doppler
Continuous wave Doppler
Spectral Doppler (duplex)
Spectral & color Doppler (triplex)
Power Doppler
11. All Doppler ultrasound examinations should
be performed with:
Tahmasebpour HR et al. RadioGraphics 2005 ; 25 : 1561 – 1575.
• Gray-scale US
• Color Doppler
• Spectral Doppler
• Power Doppler
14. Doppler shift frequency & angle of insonation
Thrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.
Elsevier Churchill Livingstone, London, 2nd edition, 2005.
15. Use of spectral baseline
Normal baseline
Inverted baseline
Dropping baseline
16. 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.
17. 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
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 direction
C Speed of sound in soft tissue (1 540 m/sec)
∆ F = 2 F0 V Cos Ө / C
19. Percentage error in velocity measurements
& angle of insonation
In order to minimize this error,
angles of insonation > 60% should not be used
20. 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.
22. Changing position of the transducer
IntercostalTransabdominal Subcostal
Kruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.
23. 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
24. 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.
25. 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.
26. Spectral aliasing
CCA
Dropping baseline Increasing scalePeaks cross baseline
Rubens DJ et al. Doppler artifacts & pitfalls.
Ultrasound Clin 2006 ; 1 : 79 – 109.
29. 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
30. 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 of
color map
Color write
priority
Baseline
wall filter
31. Inversion of color flow
Kruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.
Reversal of this inversion
Appropriate directional flow noted
Portal venous flow appears blue
Falsely suggests flow reversal
33. 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
34. Doppler angle effects
Thrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.
Elsevier Churchill Livingstone, London, 2nd edition, 2005.
35. Color box steering
Changing angle of insonation
Large angle
Unusable image
Small angle
Good image
Moderate angle
Flow 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.
36. 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.
37. Adjusting color velocity scale
Kruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.
Color velocity scale 2 cm/sec
Color 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
38. 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.
40. 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%
41. Adjusting color gain
Flow „bleeding out‟ of the vessel
Color gain set too high
Thrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.
Elsevier Churchill Livingstone, London, 2nd edition, 2005.
42. 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.
43. Pseudo-thrombosis of main PV
Adjusting velocity & angle of insonation
Velocity: 24 cm/sec
Wall filter: medium
Angle 90
Velocity: 7 cm/sec
Wall filter: medium
Angle < 90
Radiol Clin N Am 2006 ; 44 : 805 – 835.
44. 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.
45. Clinical & tissue-specific presets
• Clinical option General
Adult
Obstetric (etc…)
• Tissue-specific preset Abdomen
Renal
Transplant (etc...)
Kruskal JB et al.RadioGraphics 2004 ; 24 : 657 – 675.
Once a transducer selected
preset choices includes:
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 motion
Rubens DJ et al. Doppler artifacts & pitfalls.
Ultrasound Clin 2006 ; 1 : 79 – 109.
48. Advantages of power mode Doppler
• No aliasing
• Angle independent
• Increased sensitivity to detect low-velocity flow
Distinguish pre-occlusive from occlusive lesions
Superior depiction of plaque surface morphology
• Useful in imaging tortuous vessels
• Increases accuracy of grading stenosis
50. Disadvantages of power Doppler imaging
• Do not provide velocity of flow
• Do not provide direction of flow
New machines provide direction of flow in power mode
• Very motion sensitive (poor temporal resolution)
Less suitable for rapid scan along vessels
52. 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
53. 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
54. 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.
55. High & low resistance arterial flow
High-resistance flow
SFA
Low-resistance flow
ICA
Myers KA & Clough A. Making sense of vascular ultrasound. Arnold, London, 2004.
56. Arterial high resistance flow
Typical normal Doppler spectra
Normal anterior tibial arteryTriphasic flow
58. Effect of exercise on flow
Dorsalis Pedis Artery at rest
Triphasic flow
Thrush A, Hartshorne T. Peripheral vascular ultrasound: How, why and when.
Elsevier Churchill Livingstone, London, 2nd edition, 2005.
DPA following exercise
Monophasic hyperemic flow
59. Arterial monophasic flow
• Hyperemic
Exercise
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
60. Tardus-Parvus wave
Distal 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
65. Aacleration time & PSV
Early systolic pick
AJR - Dec 1995
Biphasic with late systolic pick
Monophasic with late systolic pick
66. AT & AI according to degree of stenosis
Moderate stenosis
50 – 85%
Normal Severe stenosis
> 85 %
67. Measurement of volume flow
Volume = Cross-sectional area Mean velocity 60
(ml/min) (cm2) (cm/sec)
Cross-sectional area (cm2): π d2 / 4
d: diameter
68. Doppler equation
Converting 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 direction
C Speed of sound in soft tissue (1 540 m/sec)
∆ F = 2 F0 V Cos Ө / C
69. ∆ 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 equation
Converting Doppler shift frequency to velocity
70. Blood flow & PSV changes related
to severity of arterial stenosis
Myers KA & Clough A. Making sense of vascular ultrasound. Arnold, London, 2004.
71. 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
72. 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
73. Post-stenotic zone/Spectral broadening
Proportional to severity of stenosis
• Cannot be precisely quantified (evaluated visually)
Fill-in of spectral window > 50% diameter reduction
Severely disturbed flow > 70% diameter reduction
High amplitude & low frequency signal
Low amplitude & high frequency signal
Flow reversal – Poor definition of spectral border
• May be only sign of stenosis: calcified plaque
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, & FMD3
1AVF: Arterio-Venous Fistula
2AVM: Arterio-Venous Malformation
3FMD: Fibro-Muscular Dysplasia
76. Color Doppler bruit
Extensive soft tisuue color Doppler bruit surrounds
the carotid bifurcation with 90% ICA stenosis
77. Venous valve
Two cups of a valve clearly seen
It is uncommon to see venous valves with this clarity
78. 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
79. 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
81. 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
82. Compressibility of veins
Do not press too hard since the normal vein collapses
very easily making it difficult to find11
83. Incompressibility = Thrombus
Do not compress vein more than necessary in recent thrombus
Fear of detaching thrombus to cause PE
Myers KA & Clough A. Making sense of vascular ultrasound. Arnold, London, 2004.
85. 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
87. 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
90. 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.
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.
AI: acceleration index Systolic upslope/transducer frequency (cm/s2)
Doppler spectrum showing the measurement of PSV & 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.
