Doppler edelman ch 19 and color doppler pp, spectral analysis pp

Question 1

doppler shift is also called _________

Answer 1

doppler frequency

Question 2

the process of extracting the low doppler frequency from the transducer carrier frequency is called ____________

Answer 2

demodulation

Question 3

doppler shift(Hz) equation

Answer 3

doppler shift(Hz)= reflected frequency - transmitted frequency

Question 4

if doppler shift is positive (frequency higher than the transmitted frequency), what does that mean

Answer 4

blood cells are traveling toward the transducer

Question 5

doppler frequencies indicate __________, not speed

Answer 5

velocity

Question 6

speed vs velocity

Answer 6

speed in magnitude
velocity is magnitude and direction

Question 7

when velocity is halved, the doppler shift is __________

Answer 7

halved

Question 8

flow towards transducer is where on baseline

Answer 8

above baseline

Question 9

simultaneous anatomic imaging and doppler is called _______________

Answer 9

duplex imaging

Question 9

what term is used for bidirectional doppler

Answer 9

phase quadrature or quadrature detection

Question 10

what is the most common error associated with doppler ultrasound

Answer 10

aliasing

Question 11

what is the very top or very bottom of the spectral display called

Answer 11

nyquist limit

Question 12

what is the part of the spectrum that appears on the the opposite side after reaching its limit

Answer 12

aliasing

Question 13

can aliasing happen with continuous wave doppler

Answer 13

No, only with pulsed doppler

Question 14

nyquist limit (hz) equaltion

Answer 14

= PRF(HZ) / 2

Question 15

2 ways to avoid aliasing are

Answer 15

raise the nyquist limit
reduce the doppler shift

Question 16

produces a continuously alternating voltage that drives the element

Answer 16

Oscillator

Question 17

detects the difference between source and reflected frequency & determines the Doppler shift (Doppler shift are normally in the audible range and are applied to a loudspeaker)

Answer 17

Doppler detector

Question 18

analyzes the spectrum for visual display

Answer 18

Spectrum analyzer

Question 19

Doppler detector that has the ability to determine positive and negative shifts contained in incoming echoes and to separate them into two channels for display
-Two output channels
-Represents forward (positive Doppler shift) and reverse flow (negative Doppler shift)

Answer 19

Phase quadrature detector

Question 20

Performed by a high-pass (wall) filter
-Eliminates high-intensity, low-frequency
Doppler shift echoes resulting from
vessel or heart wall motion
-Rejects strong echoes that obstruct
weaker echoes

Answer 20

Wall filter

ADJUST WALL FILTER WHEN NEAR WALL

Question 21

Same crystal to both transmit and receive

Presents one-dimensional information audibly and visibly

Has the ability to select listening depth

Answer 21

PULSED WAVE DOPPLER

Question 22

Allows operator to separate flow information from two vessels or to localize within a vessel
-Uses a “gate”
-When open, allows the passage of voltages representing echoes; when closed, prevents the passage of voltages
- Determined using echo-arrival time (corresponds to depth of reflector)
-Gate should be open to 1/2 width of the vessel to prevent artifactual spectral broadening

Answer 22

Range selectivity -

Question 23

Pulser generates pulses of ___________ cycles

PULSED WAVE DOPPLER

Answer 23

5-30 cycles

Question 24

Autocorrelation is a ______________ that is used to compare each echo to the corresponding echo from the previous pulse to determine motion Autocorrelation is used with color Doppler because of the enormous amount of Doppler information that requires processing. Typically 100 to 400 Doppler samples per scan line (more pulses = improved accuracy) Autocorrelation is slightly less accurate, but substantially faster, than FFT Decreases frame-rate as it is displayed as an over-lay on the gray scale image

Answer 24

digital process

Question 25

3 components of color flow

Answer 25

Hue Saturation Luminance

Question 26

perceived color, can demonstrate flow disturbances and turbulence

Answer 26

hue

Question 27

Hue used to indicate the ________________ Blue: negative shift (away from transducer) Red: Positive shift (towards transducer)

Answer 27

direction of flow

Question 28

_____________ – the amount of color in a mix with white, represents magnitude (# of RBCs) moving at that velocity

Answer 28

Saturation

Question 29

______________ – brightness of color represents echo amplitude (velocity)

Answer 29

Luminance

Question 30

top color indicates blood coming to/away from transducer

Answer 30

to

Question 31

how to increase color fill in......3 ways

Answer 31

Angle color box with vessel (decreases Doppler <) Decrease scale (too low if aliasing) Increase color Doppler gain until get “speckle” then decrease until speckle is gone

Question 32

___________ or color bleed artifact occurs when the color signal indicating blood flow extends beyond its true boundaries, spreading into adjacent regions with no actual flow.

Answer 32

Blooming

Question 33

The packet size is the number of sound bursts (pulses) transmitted per color scan line to determine blood velocities and assign a color. How Many? The number of pulses per line is termed: ensemble length, packet size, dwell time or shots per line (these are synonymous names). How Long: The number of pulses transmitted in one second is the pulse repetition frequency (PRF). How many of those pulses are fired on each scan line is the ensemble length.

Answer 33

Doppler (Color) Packets info just read

Question 34

color doppler energy Also called Ultrasound Angio, Power Doppler, Power Angio demonstrates or does not demonstrate direction?

Answer 34

does not

Question 35

Frequencies of complex signal separated through process of ____________

Answer 35

spectral analysis

Question 36

what does spectral mean

Answer 36

collection or assortment

Question 37

what does analysis mean

Answer 37

to analyze or examine

Question 38

The technique for identifying frequency components in a complex signal or waveform and spreading them out in frequency order

Answer 38

spectral analysis

Question 39

Spectral analysis is performed in a Doppler Instrument _________ and __________

Answer 39

electronically and mathematically

Question 40

spectral analysis is accomplished digitally by the __________

Answer 40

Fast Fourier Transform (FFT)

Question 41

A mathematical technique Identifies individual components that comprise the complex signal Process of separating a waveform into a series of single frequency sine-wave components

Answer 41

Fast Fourier Transform (FFT)

Question 41

___________ - each analysis presented as a single vertical line representing the bandwidth

Answer 41

Frequency

Question 42

__________ - represented by the various brightness levels; represents the number of RBCs moving at that velocity

Answer 42

Magnitude

Question 43

_________ - dimension of time obtained by sampling the Doppler signal repeatedly in small increments of a few milliseconds

Answer 43

Time

Question 44

Random movement of RBCs causes many different Doppler shift frequencies to be detected RBC Doppler shift frequencies normally grouped together, forming a spectral tracing that is narrow in systole and wide in late diastole

Answer 44

doppler waveform wording on board

Question 45

what are some organs with low resistant blood flow

Answer 45

brain, liver, kidneys will take all the blood they can get

Question 46

spectral window is good. when spectral window starts closing it means _________

Answer 46

stenosis

Question 47

________________ and window reduction are equivalent terms.

Answer 47

spectral broadening

Question 48

Narrow spectra are seen in the center of the vessel and broad spectra are seen near the walls (slower flow) Narrow spectra are seen in large vessels and broad spectra are seen in small vessels This is because in a small vessel we are forced to sample the fastest flow (center) because of the size of the vessel

Answer 48

dont quite understand it

Question 49

Spectral broadening can be produced artifactually by ____________________ Can also be produced by using a large gate (including flow across the vessel)

Answer 49

excessive Doppler receiver gain.

Question 50

_____________ provide information about flow at the site of measurement and distal to it (resistance) Peak flow speeds and degree of spectral broadening indicate the degree of stenosis

Answer 50

Spectral tracings

Question 51

Accurate identification of spectral tracing requires minimum __________ samples per second

Answer 51

two

Question 52

High velocities appear as negative sine - called _______________ A wrap-around of the Doppler signal

Answer 52

aliasing

Question 53

if you cant change nyquist limit scale anymore then change ______________

Answer 53

focal zone amount or depth

Question 54

3 parts of triphasic flow

Answer 54

Systole - high frequency; large forward velocity peak produced by systole Early diastole - Brief phase of flow reversal Late diastole - Low- velocity forward flow

Question 55

A _____________ will have abnormally high peak systolic frequency signal

Answer 55

stenosis

Question 56

___________ to stenosis or occlusion - single forward velocity component, flow remains above baseline (no reversal)

Answer 56

Distal

Question 57

(decreased/Increased) peripheral resistance - peak systolic frequency lower than normal, waveform flat and rounded

Answer 57

increased

Question 58

___________ ultrasound is the machines ability to display real time scanning with Doppler Spectral analysis at the same time.

Answer 58

Duplex

Question 59

____________ ultrasound is the machines ability to display real time scanning with Doppler Spectral analysis and color overlay all at the same time.

Answer 59

Triplex

Question 60

Boards: Tardus parvus refers to a pattern of Doppler ultrasound spectral waveform resulting from arterial stenosis. The phenomenon is observed downstream to the site of stenosis, and is due to reduced magnitude of blood flow through the narrowed vessel during ventricular systole

Question 60

type of waveform pulsatile, phasic, non phasic, aphasic

Answer 60

pulsatile

Question 61

type of waveform pulsatile, phasic, non phasic, aphasic

Answer 61

phasic

Question 62

type of waveform pulsatile, phasic, non phasic, aphasic

Answer 62

nonphasic

Question 63

type of waveform pulsatile, phasic, non phasic, aphasic

Answer 63

aphasic

Question 64

Pathologic causes of nonphasicity may be considered including: Cirrhosis Spectral broadening is due to the narrowed caliber of compressed hepatic veins Hepatic vein thrombosis (Budd-Chiari syndrome) hepatic vein thrombosis is much less common than portal vein thrombosis.

Question 65

When nyquist limit is increased so is _______

Answer 65

Prf

Question 66

Higher prf (increases/reduces) sensitivity to low velocities

Answer 66

Reduces

Question 67

The ___________ is a change in frequency that occurs when a wave hits a moving reflector

Answer 67

Doppler effect

Question 68

The change in frequency caused by motion is called the _____________________

Answer 68

Doppler shift frequency

Question 69

received freq minus source frequency =

Answer 69

doppler shift frequency

Question 70

2 things that makes the doppler shift frequency positive

Answer 70

received frequency greater than transmitted frequency If the RBC’s (a.k.a. scatterer, reflector, receiver) are approaching the transducer

Question 71

2 things that makes the doppler shift frequency negative

Answer 71

➢ If the received frequency is less than the transmitted frequency: negative shift ➢ If the RBC’s (a.k.a. scatterer, reflector, receiver) are moving away from the transducer: negative shift

Question 72

Know all three formulas for Doppler equation on p. 180 in Kremkau

Question 73

Doppler shift is proportional to:

Answer 73

➢ Flow speed ➢ Operating frequency

Question 74

The Doppler shift is dependant on the Doppler angle in the form of Cosine. ➢ The ___________ the Doppler angle the less the Doppler shift ➢ Said differently: If the Doppler angle increases the frequency decreases.

Answer 74

larger

Question 75

Typical Ranges ➢ Flow speeds: 10-100cm/s ➢ Doppler angles 30-60 ° ➢ Operating frequencies 2-10 MHz ➢ Doppler shifts in range of 100 Hz to 11kHz (vascular studies) ➢ Range of intensities 0.2-400 mW/cm2

Question 76

does continuous wave doppler have aliasing or nyquist limit?

Answer 76

no

Question 77

Aliasing occurs more easily with higher/lower transducer frequencies.

Answer 77

higher Lower frequency transducers are not as likely to reach the Nyquist limit.

Question 78

A Doppler instrument that can distinguish between positive and negative shifts is called _________.

Answer 78

bi-directional

Question 79

A pulse echo system should have a ______ Q factor. A ________ Q factor implies a short spatial pulse length, which means higher spatial resolution.

Answer 79

low

Question 80

At least ________ samples per cycle are required to accurately identify a sine or cosine wave.

Answer 80

two

Question 81

____________ means a vertical thickening of the spectral trace.

Answer 81

Spectral Broadening

Question 82

Duplex scanning

Answer 82

B scan and spectral analysis

Question 83

Triplex scanning

Answer 83

B scan, spectral and color all displayed

Question 84

These high intensity, low frequency Doppler shifted echoes from the wall are often called ____________

Answer 84

‘clutter’