Lecture 3 Flashcards
FFT
Breaks down the range and mixture of the Doppler signals into individual components.
Range Gated PWD
Only the velocities within the sample volume are represented
Normal Waveform
- Systole (PSV)
- Early Diastole
- Late Diastole (EDV)
What Information• Source of point of origin of Signal
- Source of point of origin of Signal
- Amplitude of returning echoes
- Pulsatility and wave characteristics of waveform during the cardiac cycle
- Acceleration Rate
- Direction of Flow
- Velocity of Flow
Gray scale spectrum of amplitude
White is the highest amplitude, black is the lowest or absence of amplitude.
spectral broadening
Distribution of amplitudes across the frequency spectrum is of considerable diagnosEc value.
narrow range of amplitude
laminar flow
wide range of amplitudes
spectral broadening
Three Basic Waveform Pulsatility Features
continuous
systolic
backflow
continuous waveform
Low pulsatility with relatively high levels of diastolic flow compared to the peak systolic velocity
found in arteries that supply organs (brain, kidney, liver)
systolic waveform
high pulsaElity with low diastolic flow components
backflow waveform
reverse flow pattern seen at end systole
acceleration rate
Rate of change in velocity, particularly noted on the leading edge of systole
most often used in intra renal arteries
tardus parvus
slow acceleration
what does delayed acceleration look like?
positive doppler shift
flow towards transducer
negative doppler shift
away from transducer
