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PTE Masters Ravi > Doppler Ultrasound > Flashcards

Doppler Ultrasound Flashcards

1
Q

Why do you need the spectral doppler aligned as much as you can with the cursor?

A

The probe only measured direct RBC that coming toward or away at a direct angle

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2
Q

What is the cosine of 0?

A

Cosine or 0 = 1

(Beam is directly in line)

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3
Q

What is the cosine of 90?

A

Cosine of 90 = 0

(Why perpendicular structures are not measured)

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4
Q

What is the doppler equation?

A

(Change in) Delta F (Doppler shift) = V (Cos Ø) 2FT/C

FT = Transmitted frequency

Cos Ø = Angle between velocity of probe and RBC flow

C = Speed of ultrasound in Soft tissue (1540 m/s)

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5
Q

What angle will you start to have errors in velocities when using spectral doppler cursors?

A

20-30 degrees off true alignment start to have Doppler shift errors

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6
Q

What is your Pulse Repetition Frequency with continuous wave doppler?

A

infiniti (Always sending signals)

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7
Q

Theoretically, what is your nyquist limit with continous wave doppler?

A

Super high (does not limit)

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8
Q

What is the aliasing veloicty of Continous wave doppler?

A

Doesnt have one

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9
Q

What is the benefit of continous wave doppler?

A

You are able to measure very high peak velocities

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10
Q

What can continous wave doppler not do?

i.e. What are the limitations of Continous wave doppler

A

Range ambiguity (Cannot tell if peak velocities coming from any point)

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11
Q

How many crystals does continous wave doppler have?

A

Two

  1. One continously sending signals
  2. One continuously listening to signals
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12
Q

What are the advantages of continous wave doppler?

A
  1. Velocity will not alias
  2. No nyquist limit
  3. Infinite pulses per minute
  4. High velocities measured
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13
Q

What is the pulse wave doppler needed to measure diastolic function through the mitral valve?

A
  1. PWD ont he mitral tips (Inflow velocities) (E wave and A wave)
  2. Tissue doppler (Lower velocity but higher amplitude) (E’ and A’)
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14
Q

What E’ is considered normal diastolic function?

A

E’ > 10 cm/sec

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15
Q

What are the advantage of PWD?

A
  1. Range resolution (measure velocities at a specific location)
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16
Q

What are the limitations of PWD?

A
  1. Nyquist limit (AKA max doppler shift) before aliasing velocity occurs

Aliasing = Limited Max Velocity

Nyquist limit = Nyquist frequency

Nyquist limit = Max Delta F = 1/2 Pulse Range Frequency (PRF)

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17
Q

How do high velocities on PWD appear?

A

Negative (Due to aliasing)

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18
Q

What are the ways you could decrease aliasing?

A
  1. Use a low transmitted frequency
  2. Decrease the depth (increase Pulse Range Frequency PRF)
  3. Optimize the baseline
  4. Use Continous Wave Doppler
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19
Q

How can you remember color flow doppler what is blue and red?

A

BART (to the probe)

Blue = Away

Red = Toward

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20
Q

How does turbulent blood flow appear when it goes towards and away from the probe?

A

Away = Green

Toward = Yellow

BART

GAYT

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21
Q

What are the limitations of Color Flow Doppler?

A
  1. Aliasing (Form of PWD)
  2. Decreased Temporal Resolution (Frame rate)
  3. Velocity measurements are estimates (Mean Velocity)
  4. Not as exact as PWD and CWD
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22
Q

What are the cosine values of:

Cosine 0 degrees

Cosine 30 degrees

Cosine 45 degrees

Cosine 60 degrees

Cosine 90 degrees

A

Cosine 0 degrees = 1

Cosine 30 degrees = [Square root of 3] / 2

Cosine 45 degrees = [Square root of 2] / 2

Cosine 60 degrees = [Square root of 1] / 2 = 1/2

Cosine 90 degrees = 0

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23
Q

What is the optimal incidence angle for pulse wave doppler?

A

Parallel (Zero degrees) to blood flow

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24
Q

An U/S probe interrogates a blood vessel with an incident angle of zero degrees. The probe emits a frequency of 10 MHz and the returning echos have a vessel frequency of 10.5 MHz. What is the velocity of the blood vessel

A
  1. Use Doppler Equation

Velocity = Delta F / [Cos angle * 2 FT / C]

Velocity = [10.5 - 10 MHz] / [Cos 0 degrees * 2 (10 MHz) / (1540 m/s)]

Answer = D (38.5 m/s)

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25
Q

An U/S probe interrogates a blood vessel with an incident angle of 60 degrees. The probe emits a frequency of 10 MHz and the returning echos have a vessel frequency of 10.5 MHz. What is the velocity of the blood vessel?

A

77 m/s

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26
Q

A 12 MHz transducer interrogates blood flow using PWD in a vessel with a blood flow velocity of 100 cm/sec and a pulse repetition frequency of 6000 Hz. Which of the following is the highest Doppler shift that can be measured?

A

C = 3000 Hz

Highest doppler shift = Nyquist limit = Half of the PRF (Pulse wave frequency, which in this vignette is 6000 Hz)

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27
Q

What do wall filters function to do?

A

Filter out part of Doppler signals

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28
Q

What do low pass wall filters do?

A

Filter out high velocities (Allows low velocities to PASS)

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29
Q

What do high pass wall filters do?

A

Filters out low velocities (Allows high velocities to pass)

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30
Q

What are low pass wall filters used for?

A

Tissue Doppler Imaging (TDI)

TIssue movement = Low velocities, High amplitude signals

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31
Q

What are high pass wall filters used for?

A

Used for blood flow velocities

(HIgh velocity, Low amplitude signals with high pass filter on and low pass filter off)

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32
Q

What are the 5 functions of an ultrasound receiver?

A
  1. Amplification
  2. Compensation
  3. Compression
  4. Demodulation
  5. Rejection
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33
Q

What does rejection do on echo?

A

Rejects low amplitude 2D, 3D and M-mode signals

Is does NOT reject doppler

Very low level signals are ignored

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34
Q

What are the two other names for rejection in echo?

A
  1. Threshold
  2. Suppression
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35
Q

What frequency range is high pass wall filtering set at?

A

200 - 800 Hz

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36
Q

For tissue doppler

  1. What filter is on?
  2. What filter is off?
  3. What amplitude signal is on?
  4. What velocity?
A

For Tissue Doppler (TDI)

Low Pass filter on

High pass filter off

High amplitude

Low velocity

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37
Q

For blood flow velocities doppler

  1. What filter is on?
  2. What filter is off?
  3. What amplitude signal is on?
  4. What velocity?
A

For blood flow velocities doppler

Low Pass filter OFF

High pass filter ON

Low amplitude

High velocity

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38
Q

What is the difference from rejection vs. Wall Filters?

A

Rejection involves amplitude of the 2D signals

  • Low amplitude signals are ignored

Wall Filters* acceptance/rejection of different *doppler shifts

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39
Q

Again, what is the doppler equation?

A

Change in Frequency (Ft - Fr) = Blood flow velocity (cosine angle) * 2Ft / C(speed of sound)

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40
Q

Why is “2” adjacent to the Frequency transmitted in the Doppler equation?

A

2 Doppler shifts

  • 1st Doppler shift occurs when sound wave strikes RBC (Reception of sound wave by the red cell by itself creates a doppler shift)
  • 2nd Doppler shift - Reception of the reflected sound wave by the transducer moving from the RBC
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41
Q

What is a power doppler?

What does it NOT have? (2 things)

A

Only signifies presence of a doppler shift (Only tells you have a +/- Delta F

NO Direction

No Speed

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42
Q

What is power doppler known as? (2 synonymous terms)

A
  1. Energy Mode
  2. Color Angio
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43
Q

What are the 3 advantages of Power Doppler?

A
  1. Increased sensitivity to low flow
  2. Unaffeted by angle unless its exactly 90 degrees
  3. Unaffected by aliasing since velocity is ignored
44
Q

What are the 3 disadvantages of Power Doppler?

A
  1. Lower frame rates than conventional color flow doppler
  2. No measure of velocity or direction
  3. Susceptible to motion of the transducer, patient, or soft tissues which may result in a burst of color or flash artifact
45
Q

Wall filters function to filter out what?

A

Part of the doppler shift (Delta F which is approximately equatl to velocities)

46
Q

What is the relationship between frequency and velocities in terms of low vs. high pass wall filters?

A

Frequency and velocity are inversely related

(See picture)

47
Q

See picture to answer the question

A

Valve Clicks = At 1

Left = Opening click

Right = Closing click

48
Q

Which of the following parameters is determined by the ultrasound source and the medium through which sound travels?

A. Period

B. Wavelength

C. Frequency

D. Amplitude

E. Velocity

F. Intensity

A

Wavelength

This is the ONLY parameter determine by the sounds SOURCE and the MEDIUM

49
Q

Which of the following parameters is determined by the ultrasound source ONLY?

A. Period

B. Wavelength

C. Frequency

D. Amplitude

E. Velocity

F. Intensity

A

Amplitude

Intensity

50
Q

Which of the following parameters is determined by the ultrasound medium ONLY?

A. Period

B. Wavelength

C. Frequency

D. Amplitude

E. Velocity

F. Intensity

51
Q

Velocity of the wavelength is determined by what 2 attributes of the medium?

A
  1. Stiffness (As stiffness increases, velocity increases)

Stiff & Speed directly correlated

  1. Density (As density increases, velocity decreases)

Density & Speed indirectly correlated

52
Q

RANK THE FOLLOWING SPEED THROUGH ULTRASOUND MEDIUMS?

AIR

BONE

FAT

LUNG

SOFT TISSUE

A

BONE (FASTEST)

Soft Tissue

Fat

Lung

Air (Slowest)

53
Q
  1. How does the PWD profile change if you place the gate more in the LA vs. right at the leaflet tips (Picture attached)?
  2. How does the Peak E velocity change?
  3. How does the E wave deceleration time change?
A
  1. Peak E Velocity increases
  2. E wave Deceleration time decreases
54
Q

What velocity location should we use?

(see image)

A

Answer = Location 1 (Max velocity we see going away from the probe)

Once this velocity is exceeded, then we see red (this is termed aliasing)

At location “C” = location 1

55
Q

Other than myocardial velocities with Tissue Doppler Imaging (TDI), what is the other utilization of TDI?

A

Deformation Patterns = Strain and Strain Rate

56
Q

What is the function of the reject function?

A

Eliminates very low level (amplitude) signals decreasing noise on the 2D image

Rejection = Function of the Receiver

57
Q

What is the other 2 names for rejection on echo imaging?

A

Threshold

Suppression

58
Q

What is the difference in rejection vs. high pass wall filter?

A

Rejection = Low amplitude signals

HIgh pass = Deals with Delta F (Doppler signals)

59
Q

Which is the following is least likely to be true with regard to the low pass wall filter utilized for Doppler ultrasound?

A. It eliminates high frequency signals (Larger doppler shifts)

B. It allows measurement of low velocities

C. It is utilized to measure tissue Doppler velocities

D. It eliminates low amplitude signals

E. All of the listed choices are true with regard to the low pass filter.

A

D = It eliminates low amplitude signals

A-C are true

D refers to the reject function

60
Q

What is the velocity of sound waves?

A

1540 m/sec

1.54 mm/ msec (microsecond)

61
Q

How do you convert MHz to a function a microseconds (µsec)?

A

1 MHz = 1 cycle/1µsec

62
Q

What is the wavelength of a 4 MHz TEE probe?

A

0.39 mm

Velocity = Frequency x Wavelength

Wavelength = Velocity / Frequency

Wavelength = (1.54 mm/micro second) / 4 MHz

Wavelength = 0.39 mm

63
Q

Draw a CWD profile of HOCM through the aortic valve through Deep Transgastric Aortic Valve

A

Late peaking profile

64
Q

Physiologically, why does a HOCM CWD have a late peaking profile?

A

Late in systole is when the heart is the most empty = Most obstruction

65
Q

What is the CWD profile of aortic stenosis in deep TG view?

A

Looks like a tombstone image

66
Q

How do you tell the difference between MR vs AS on CWD through a deep TG image through the aortic valve

A

Timing of the peak

AS = After QRS peak (occurs during ejection after isovolumetric contraction)

MR = Before the QRS peak (During isovolumetric contraction phase)

67
Q

What are the 5 ways to decrease aliasing artifact?

A
  1. Use CWD (infinite nyquist limit)
  2. Use lower transmitted Frequency (Delta F = V Cos (Angle) 2 Ft / C)
  • Lower Ft results in Delta F being lower)
    3. Decrease depth (increase PRF)
    4. Increase PRF (Nyquist limit is 1/2 of PRF)
    5. Adjust Baseline
68
Q

What is this wave in the image?

What is the significance?

A

L wave = Signifies impaired relaxation* and *high LAP

69
Q

When you utilize PHT, what is the velocity of the 2nd point where pressure is half?

70
Q

What is PHT (Pressure half time)?

A

TIme it takes to go from Max P gradient (Max Delta P) to 1/2 Max Delta P

71
Q

If you have a large hole (Lots of regurg), then will you have a smaller or larger equilization time?

A

Big hole = Faster equalization of P

72
Q

What two valvular lesions is PHT useful for?

A

Mitral Stenosis

Aortic Regurgitation

73
Q

For Mitral Stenosis, what spectral doppler profile are you going to use to determine Mitral valve area?

Do you use systolic (regurgitation) or diastolic (mitral inflow) to determine PHT?

A

Continous Doppler

Diastolic Mitral Inflow (Bottom graph)

74
Q

If you calculate PHT of 239, what is the mitral valve area?

A

0.92 cm2

MVA = 220/ PHT

75
Q

What is the Mean Gradient (Delta P) mmHg for Mild Mitral Stenosis?

76
Q

What is the Mean Gradient (Delta P) mmHg for Moderate Mitral Stenosis?

A

5 - 10 mmHg

77
Q

What is the Mean Gradient (Delta P) mmHg for Severe Mitral Stenosis?

78
Q

What is the PHT for a normal mitral valve when evaluating for mitral stenosis?

79
Q

What is the PHT for a mitral valve when evaluating for mild mitral stenosis?

80
Q

What is the PHT for a mitral valve when evaluating for moderate mitral stenosis?

81
Q

What is the PHT for a mitral valve when evaluating for severe mitral stenosis?

82
Q

What is the dimensions of a normal mitral valve area?

83
Q

What is the dimensions of a mitral valve area with mild Mitral Stenosis?

A

1.6 - 2.5 cm2

84
Q

What is the dimensions of a mitral valve area with moderate Mitral Stenosis?

A

1.0 - 1.5 cm2

85
Q

What is the dimensions of a mitral valve area with severe Mitral Stenosis?

86
Q

How does A.I. affect the Mitral stenosis PHT?

A

Decreased PHT and leads to overestimate of MVA (Underestimate the degree of MS)

The pressures equilibriate more rapidly during LV filling

PHT is shorter because AI increases the LV pressure rapidly during diastole causing a shorter equilibriation time

87
Q

How does Decreased LV compliance affect the Mitral stenosis PHT?

A

Rapid equilibriation of P = Overestimate MVA and underestimate MS

88
Q

How does impaired LV relaxation affect the Mitral stenosis PHT?

A

Opposite of decreased compliance

We will have slower equilibriation pressures (increased PHT)

  • Underestimate the degree of MVA
  • Overestimate the degree of MS
89
Q

How do you estimate AI with PHT?

A

CWD through deep TG aortic valve

  • Look at diastolic flow (Measure the gradient)
90
Q

What is the pressure half time for Mild AI?

91
Q

What is the pressure half time for Moderate AI?

A

200 - 500 ms

92
Q

What is the pressure half time for Severe AI?

93
Q

What is the AI Jet/LVOT Diameter for Mild AI?

94
Q

What is the AI Jet/LVOT Diameter for Moderate AI?

95
Q

What is the AI Jet/LVOT Diameter for Severe AI?

96
Q

What is the AI Area/LVOT area for Mild AI?

97
Q

What is the AI Area/LVOT area for Moderate AI?

98
Q

What is the AI Area/LVOT area for Severe AI?

99
Q

What is the Jet Depth for Trivial AI?

100
Q

What is the Jet Depth for Mild AI?

A

Mid Anterior Leaflet of Mitral Valve

101
Q

What is the Jet Depth for Moderate AI?

A

Tip of Anterior Leaflet of Mitral Valve

102
Q

What is the Jet Depth for Severe AI?

A

Papillary Muscle head

103
Q

What is the Vena Contracta for Severe AI?

(What two views do you evaluate)?

A

ME LAX >6 mm

ME SAX Area (>7.5 mm2)

104
Q

What is the Slope of AR Jet decay for Moderate AI?

105
Q

What is the Slope of AR Jet decay for Severe AI?

106
Q

Which of the following will increase the AI PHT?

A. Sodium Nitroprusside

B. Phenylephrine

C. IABP

D. Calcium

A

A. Sodium Nitroprusside

(Decreases SVR) and will enhance forward flow and decreased AI

As AI is decreases, the PHT is increased

(All other options worsen the AI and hence drop the PHT)

PTE Masters Ravi (45 decks)

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