Lesson 23 (Part 1) Flashcards
What does spectral doppler detect? (4)
- Presence
- Speed
- Character
- Direction of flow
- Quantification of blood flow
- this is super important
When is the peak velocity?
During systolic
When is the end velocity?
During diastolic
What is spectral doppler also known as? (2)
- Pulsed doppler
2. Pulsed wave doppler
What does spectral doppler fire along?
A single scan line
How many pulses per cycle are there for spectral doppler?
5-30
Sample volume
Is a specific area that is being assessed
- the gate
Range gating
Being able to select information from a specific depth
What are you looking at in a smaller gate?
A higher velocity
What are 3 benefits for a smaller gate?
- Less noise
- Better quality
- More specific information
What is the formula for effective sample length?
1/2 SPL + gate length
What is another term for sample width?
Beam width
What is sample volume dependant on?
The user
- user defined
What is a larger gate used for?
To look for a vessel/signal
What is on the X axis for a graph of spectral doppler?
Time
What is on the y axis for a graph of spectral doppler?
Doppler shift/velocity
How does all blood move?
As a unit
When is a range of velocities obtained?
At any particular moment in time
Where does spectral doppler occur?
Within the signal processor
What is the known as the gate amplifier?
Beam former
What does quadrature phase detector allow?
Detection of bidirectional Doppler
- shows +/- shifts
What does a filter do?
Gets rid of the sum
What does the spectrum analyzer determine? (2)
- Each Doppler shift frequency
2. Its strength
Where does fast fourier transform occur?
Within the spectrum analyzer
Fast fourier transform
Mathematical technique to figure out the frequency spectrum
Where are the results form the fast fourier transform sent to?
Results sent to be displayed on the spectral display
FFT
Fast fourier transform
What does spectral display show?
Spectral waveforms
What does each point on the spectral display demonstrate? (3)
- Direction (+/-)
- Magnitude
- speed - Amplitude
- brightness
What factors can affect direction for spectral doppler?
- Whether it is positive or negative
- coming towards the transducer or away from it - Steering the transducer
What is everything above the baseline considered in spectral doppler?
Positive
What is everything below the baseline considered in spectral doppler?
Negative
Why is there 2 directions of flow?
Flow reversal
- this does not happen in every vessel (only in certain spots)
