Kahoot - All Post Midterm Flashcards
The reflected frequency is higher than the transmitted frequency when there is a positive shift or
Source and receiver are moving towards each other
Doppler angle is between
Flow direction and sound beam
What is related to Doppler shift
Cosine angle between flow and sound beam
Velocity of RBC
Fundamental frequency
True or false
The larger the Doppler angle the larger the Doppler shift
False
True or false
The larger the operating frequency the larger the Doppler shift
True
True or false
The lower the operating frequency used the faster the calculated velocity
False
Check formula relationship
True or false
Incorporating angle with non-zero interrogations always brings the speed up
True
Speed of blood
10-100 cm/s
Doppler angle best range
30-60
Operating frequency range in MHz
2-10 MHz
Doppler shift range
100 Hz to 11 KHz
True or false
You can hear the Doppler shift
True
Number of cycles in a pulse in Doppler u/s
5-30
Without angle correct Fd= 16 KHz, what is the shift if you use angle correct at 60 degrees?
8 kHz
Why scanning at Doppler angle more than 60 degrees not a good idea?
Increases chance of error in velocity
Which is a digital processing technique used to process colour Doppler
Autocorrelation
Which one has the higher duty factor? Pulse US or CW Doppler ?
CW (no listening time)
No colour in vessel most likely due to
No Doppler shift
Doppler angle 90 degrees
PD in Doppler is higher than in B mode, which means typically period (T) in Doppler pulse is higher than in b mode
True or false
False
Power Doppler shows blood flow ____
Presence
Ensemble length for Doppler u/s
3-32
Large ensemble length leads to (3). What does it not do
- better accuracy of Doppler shifts
- degradation of temporal resolution
- better sensitivity/detecting echoes
DOES NOT increase imaging depth
To show faster speeds you need to ______
Increase PRF
If your PRF is 10 KHz which Doppler shift will create aliasing
1/2 PRF so anything above 5 KHz
Which of these parameters you can’t control in Doppler: Wall filter PRF Nyquist limit Baseline
Nyquist limit
This control sets up a cut off amplitude limit below which echoes will show in colour
Priority
Which control will eliminate clutter?
Wall filter
What type of blood flow demonstrates straight layers of fluid sliding over each other
Laminar
Resistance to flow offered by a fluid in motion describes
Viscosity
Driving force behind blood flow
Pressure difference
A nonsteady flow with acceleration and deceleration over the cardiac cycle is ______ flow
Pulsatile
____ describes volumetric flow rate as a constant
Continuity rule
Volumetric flow rate must be constant for the three regions : prox, at and distal to stenosis because blood is neither created or destroyed
Volumetric flow rate for a short segment
Q=V*A
Besides liquids which matter is considered a fluid
Gases
Turbulent flow is a form of ____ flow
Non-laminar
The state of downstream arterioles is reflected in the ____
Arteriole diastolic flow
The Doppler equation relates the Doppler shift to the _____
Flow speed and frequency
The decreases pressure in regions of high flow speed is called __\\
Bernoulli effect
For a given flow, the greater the Doppler angle, the
Smaller the shift
Sound reflects totally at the wall-blood boundary once the Doppler angle is less than
30 degrees
What is required for flow to occur?
Pressure diff
Doppler shift does not depend on the : Speed? Direction? Operating frequency? Doppler angle?
Choose one
Flow direction
The resistance of the _____ accounts for about one half of the total resistance in the systemic circulation
Arterioles
The max normal flow speed in the circulation is ____ cm/s
100 cm/s
Variance colour maps demonstrate a change of hues from
Left to right
Which of the following Doppler techniques must be time shared?
Duplex imaging
Which system control eliminates high-intensity low-frequency Doppler shifts
Wall filter
The width of the sample volume is determined by the ____
Beam width
What advantage does spectral analysis have when compared to other Doppler techniques
Displays peak systolic velocities
The angle of incidence is not important with which Doppler display?
Power
Vertical thickening of the spectral tracing is called
Spectral broadening
Which type of bf demonstrates a chaotic flow pattern
Turbulent
Which type of blood flow would demonstrate the narrowest range of Doppler shift frequencies
Plug
Because velocity is the same across all blood flow
FF Transform
Determines Doppler spectrum
Can show slow flows in deep or small vessels
Power Doppler
The horizontal presentation in spectral display represents
Time
The vertical axis in spectral display represents
Doppler shift
Velocity
Spectral broadening may be produced by
Beam spreading in arrays
Continuous wave Doppler shifts are detected within the
Overlap area of transmitted and received beams
Motion towards the TD demonstrates
Flow above baseline
Positive Doppler shift
Advantage of pulsed Doppler
Depth of sample volume can be accurately selected
Echoes arrive from sample volume depth at a rate equal to
PRF
Poiseuille’s equation states that if the flow rate increases the
Tube diameter has increased
True or false
The maximum detectable blood flow speed with pulsed Doppler imaging is determined by aliasing
True
True or false
The Doppler shift is directly related to volumetric flow rate
False
True or false
Multiple foci are used in colour Doppler imaging
False
Also colour Doppler does NOT utilize high frame rates
