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
2
Q
What is the cosine of 0?
A
Cosine or 0 = 1
(Beam is directly in line)
3
Q
What is the cosine of 90?
A
Cosine of 90 = 0
(Why perpendicular structures are not measured)
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)
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
6
Q
What is your Pulse Repetition Frequency with continuous wave doppler?
A
infiniti (Always sending signals)
7
Q
Theoretically, what is your nyquist limit with continous wave doppler?
A
Super high (does not limit)
8
Q
What is the aliasing veloicty of Continous wave doppler?
A
Doesnt have one
9
Q
What is the benefit of continous wave doppler?
A
You are able to measure very high peak velocities
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)
11
Q
How many crystals does continous wave doppler have?
A
Two
- One continously sending signals
- One continuously listening to signals
12
Q
What are the advantages of continous wave doppler?
A
- Velocity will not alias
- No nyquist limit
- Infinite pulses per minute
- High velocities measured
13
Q
What is the pulse wave doppler needed to measure diastolic function through the mitral valve?
A
- PWD ont he mitral tips (Inflow velocities) (E wave and A wave)
- Tissue doppler (Lower velocity but higher amplitude) (E’ and A’)
14
Q
What E’ is considered normal diastolic function?
A
E’ > 10 cm/sec
15
Q
What are the advantage of PWD?
A
- Range resolution (measure velocities at a specific location)
16
Q
What are the limitations of PWD?
A
- 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)
17
Q
How do high velocities on PWD appear?
A
Negative (Due to aliasing)
18
Q
What are the ways you could decrease aliasing?
A
- Use a low transmitted frequency
- Decrease the depth (increase Pulse Range Frequency PRF)
- Optimize the baseline
- Use Continous Wave Doppler
19
Q
How can you remember color flow doppler what is blue and red?
A
BART (to the probe)
Blue = Away
Red = Toward
20
Q
How does turbulent blood flow appear when it goes towards and away from the probe?
A
Away = Green
Toward = Yellow
BART
GAYT
21
Q
What are the limitations of Color Flow Doppler?
A
- Aliasing (Form of PWD)
- Decreased Temporal Resolution (Frame rate)
- Velocity measurements are estimates (Mean Velocity)
- Not as exact as PWD and CWD
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
23
Q
What is the optimal incidence angle for pulse wave doppler?
A
Parallel (Zero degrees) to blood flow
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
- 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)
25
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?
77 m/s
26
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?
C = **3000 Hz**
Highest doppler shift = Nyquist limit = Half of the PRF (Pulse wave frequency, which in this vignette is 6000 Hz)
27
What do wall filters function to do?
Filter out part of Doppler signals
28
What do **low pass** wall filters do?
**Filter out high velocities** (Allows low velocities to PASS)
29
What do **high pass** wall filters do?
Filters out **low velocities** (Allows high velocities to pass)
30
What are **low pass** wall filters used for?
**Tissue Doppler Imaging** (TDI)
TIssue movement = Low velocities, High amplitude signals
31
What are **high pass** wall filters used for?
Used for **blood flow** velocities
(HIgh velocity, Low amplitude signals with high pass filter on and low pass filter off)
32
What are the 5 functions of an ultrasound receiver?
1. Amplification
2. Compensation
3. Compression
4. Demodulation
5. Rejection
33
What does rejection do on echo?
**Rejects** *_low amplitude_* **2D, 3D and M-mode signals**
Is does *_NOT reject_* **doppler**
Very low level signals are ignored
34
What are the two other names for rejection in echo?
1. Threshold
2. Suppression
35
What frequency range is high pass wall filtering set at?
200 - 800 Hz
36
For tissue doppler
1. What filter is on?
2. What filter is off?
3. What amplitude signal is on?
4. What velocity?
For Tissue Doppler (TDI)
Low Pass filter **on**
High pass filter **off**
High **amplitude**
Low **velocity**
37
For **blood flow** velocities doppler
1. What filter is on?
2. What filter is off?
3. What amplitude signal is on?
4. What velocity?
For **blood flow** velocities doppler
Low Pass filter **OFF**
High pass filter **ON**
**Low** amplitude
**High** velocity
38
What is the difference from **rejection** vs. **Wall Filters**?
**Rejection** involves **amplitude** of the 2D signals
- Low amplitude signals are ignored
*_Wall Filters*_ acceptance/rejection of different _*doppler shifts_*
39
Again, what is the doppler equation?
Change in Frequency (Ft - Fr) = Blood flow velocity (cosine angle) \* 2Ft / C(speed of sound)
40
Why is "**2**" adjacent to the Frequency transmitted in the Doppler equation?
**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
41
What is a **power** doppler?
What does it **NOT** have? (2 things)
Only signifies presence of a doppler shift (Only tells you have a *_+/- Delta F_*
NO **Direction**
No **Speed**
42
What is power doppler known as? (**2 synonymous terms)**
1. Energy Mode
2. Color Angio
43
What are the 3 **advantages** of **Power** Doppler?
1. Increased sensitivity to low flow
2. Unaffeted by angle unless its exactly 90 degrees
3. Unaffected by aliasing since velocity is ignored
44
What are the 3 ***_disadvantages_*** of **Power** Doppler?
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
Wall filters function to filter out what?
**Part of the doppler shift** (*_Delta F_* which is approximately equatl to **velocities**)
46
What is the relationship between frequency and velocities in terms of low vs. high pass wall filters?
**Frequency** and **velocity** are inversely related
(See picture)
47
See picture to answer the question
***_Valve Clicks_*** = At 1
**Left** = Opening click
**Right** = Closing click
48
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
**Wavelength**
This is the ONLY parameter determine by the sounds **SOURCE** and the **MEDIUM**
49
Which of the following parameters is determined by the ultrasound source ONLY?
A. Period
B. Wavelength
C. Frequency
D. Amplitude
E. Velocity
F. Intensity
**Amplitude**
**Intensity**
50
Which of the following parameters is determined by the ultrasound medium ONLY?
A. Period
B. Wavelength
C. Frequency
D. Amplitude
E. Velocity
F. Intensity
**Velocity**
51
Velocity of the wavelength is determined by **what 2 attributes** of the medium?
1. *_Stiffness_* (As stiffness increases, velocity increases)
Stiff & Speed *_directly_* correlated
2. *_Density_* (As density increases, velocity decreases)
Density & Speed *_indirectly_* correlated
52
**RANK THE FOLLOWING SPEED THROUGH ULTRASOUND MEDIUMS?**
AIR
BONE
FAT
LUNG
SOFT TISSUE
BONE (FASTEST)
Soft Tissue
Fat
Lung
Air (Slowest)
53
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?
1. Peak E Velocity increases
2. E wave Deceleration time decreases
54
What velocity location should we use?
| (see image)
**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
Other than myocardial velocities with Tissue Doppler Imaging (TDI), what is the other utilization of TDI?
**Deformation Patterns** = Strain and Strain Rate
56
What is the function of the reject function?
Eliminates very low level (amplitude) signals decreasing noise on the 2D image
Rejection = Function of the Receiver
57
What is the other 2 names for rejection on echo imaging?
Threshold
Suppression
58
What is the difference in rejection vs. high pass wall filter?
Rejection = Low amplitude signals
HIgh pass = Deals with Delta F (Doppler signals)
59
**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.
**D = It eliminates low amplitude signals**
A-C are true
D refers to the reject function
60
What is the velocity of sound waves?
1540 m/sec
1.54 mm/ msec (microsecond)
61
How do you convert MHz to a function a microseconds (µsec)?
1 MHz = 1 cycle/1µsec
62
What is the wavelength of a 4 MHz TEE probe?
**0.39 mm**
Velocity = Frequency x Wavelength
Wavelength = Velocity / Frequency
Wavelength = (1.54 mm/micro second) / 4 MHz
**Wavelength = 0.39 mm**
63
Draw a CWD profile of HOCM through the aortic valve through Deep Transgastric Aortic Valve
Late peaking profile
64
Physiologically, why does a HOCM CWD have a late peaking profile?
**Late in systole** is when the heart is the **most empty** = *_Most obstruction_*
65
What is the CWD profile of aortic stenosis in deep TG view?
Looks like a tombstone image
66
How do you tell the difference between MR vs AS on CWD through a deep TG image through the aortic valve
**Timing of the peak**
AS = After QRS peak (occurs during ejection after isovolumetric contraction)
MR = Before the QRS peak (During isovolumetric contraction phase)
67
What are the 5 ways to decrease aliasing artifact?
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
What is this wave in the image?
What is the significance?
**L wave** = Signifies *_impaired relaxation*_ and _*high LAP_*
69
When you utilize PHT, what is the velocity of the 2nd point where pressure is half?
71%
70
What is PHT (Pressure half time)?
TIme it takes to go from Max P gradient (Max Delta P) to 1/2 Max Delta P
71
If you have a large hole (Lots of regurg), then will you have a smaller or larger equilization time?
Big hole = Faster equalization of P
72
What two valvular lesions is PHT useful for?
Mitral Stenosis
Aortic Regurgitation
73
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?
Continous Doppler
Diastolic Mitral Inflow (Bottom graph)
74
If you calculate PHT of 239, what is the mitral valve area?
**0.92 cm2**
MVA = 220/ PHT
75
What is the Mean Gradient (Delta P) mmHg for **Mild** Mitral Stenosis?
\<5 mmHg
76
What is the Mean Gradient (Delta P) mmHg for **Moderate** Mitral Stenosis?
5 - 10 mmHg
77
What is the Mean Gradient (Delta P) mmHg for **Severe** Mitral Stenosis?
\>10 mmHg
78
What is the PHT for a **normal** mitral valve when evaluating for mitral stenosis?
30 - 89
79
What is the PHT for a mitral valve when evaluating for **mild** mitral stenosis?
90 - 150
80
What is the PHT for a mitral valve when evaluating for **moderate** mitral stenosis?
151 - 219
81
What is the PHT for a mitral valve when evaluating for **severe** mitral stenosis?
\>220
82
What is the dimensions of a normal mitral valve area?
\> 2.5 cm2
83
What is the dimensions of a mitral valve area with **mild** Mitral Stenosis?
1.6 - 2.5 cm2
84
What is the dimensions of a mitral valve area with **moderate** Mitral Stenosis?
1.0 - 1.5 cm2
85
What is the dimensions of a mitral valve area with **severe** Mitral Stenosis?
\< 1.0 cm2
86
How does **A.I.** affect the Mitral stenosis PHT?
**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
How does **Decreased LV compliance** affect the Mitral stenosis PHT?
**Rapid equilibriation of P** = **Overestimate MVA** and **underestimate MS**
88
How does **impaired LV relaxation** affect the Mitral stenosis PHT?
Opposite of decreased compliance
We will have slower equilibriation pressures (increased PHT)
- **Underestimate** the degree of **MVA**
- **Overestimate** the degree of **MS**
89
How do you estimate AI with PHT?
CWD through deep TG aortic valve
- Look at diastolic flow (Measure the gradient)
90
What is the pressure half time for **Mild** AI?
\>500 ms
91
What is the pressure half time for **Moderate** AI?
200 - 500 ms
92
What is the pressure half time for **Severe** AI?
\<200 ms
93
What is the AI Jet/LVOT Diameter for **Mild** AI?
\<25%
94
What is the AI Jet/LVOT Diameter for **Moderate** AI?
25-64%
95
What is the AI Jet/LVOT Diameter for **Severe** AI?
\>65%
96
What is the AI Area/LVOT area for **Mild** AI?
\<5%
97
What is the AI Area/LVOT area for **Moderate** AI?
5-59%
98
What is the AI Area/LVOT area for **Severe** AI?
\>60%
99
What is the Jet Depth for **Trivial** AI?
LVOT
100
What is the Jet Depth for **Mild** AI?
Mid Anterior Leaflet of Mitral Valve
101
What is the Jet Depth for **Moderate** AI?
Tip of Anterior Leaflet of Mitral Valve
102
What is the Jet Depth for **Severe** AI?
Papillary Muscle head
103
What is the Vena Contracta for Severe AI?
(What two views do you evaluate)?
ME LAX **\>6 mm**
ME SAX Area (**\>7.5 mm2**)
104
What is the Slope of AR Jet decay for **Moderate** AI?
\>/= 2 m/s
105
What is the Slope of AR Jet decay for **Severe** AI?
\>/= **3 m/s**
106
Which of the following will increase the AI PHT?
A. Sodium Nitroprusside
B. Phenylephrine
C. IABP
D. Calcium
**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)_*
