Ultrasound Physics - 19\doppler Part Ii

Front 1

The following factors relate to what type of doppler?
- range resolution
- sample volume
- limited maximum velocity (Nyquist)
- aliasing

Back 1

Pulsed Doppler

Front 2

The following factors relate to what type of doppler?
- range ambiguity
- region of overlap
- unlimited maximum velocity
- no aliasing

Back 2

CW Doppler

Front 3

The following factors relate to what type of transducer?
- at least one crystal
- damped PZT
- low Q-factor
- wide bandwidth
- lower sensitivity

Back 3

Pulsed Doppler Transducer

Front 4

The following factors relate to what type of transducer?
- at least two crystals
- undamped PZT
- high Q-factor
- narrow bandwidth
- higher sensitivity

Back 4

CW Doppler Transducer

Front 5

The following factors relate to what general type of modality?
- normal incidence
- higher frequency
- pulsed wave only
- minimum of 1 crystal

Back 5

Imaging

Front 6

The following factors relate to what general type of modality?
- 0/180 degrees
- lower frequency
- pulsed or CW
- min of 1 (pulsed) or 2 (CW) crystals

Back 6

Doppler

Front 7

In this modality, velocity information is coded into colors and superimposed on a 2D grayscale, anatomic image

Back 7

Color Flow Doppler

Front 8

Is spectral doppler considered qualitative or quantitative?

Back 8

Quantitative

Front 9

Is color flow doppler considered qualitative or quantitative?

Back 9

Qualitative

Front 10

Since color flow doppler is based on ___ techniques, it has the same advantages (___) and disadvantage (___)

Back 10

Pulsed Wave
+ Range Resolution/Specificity
- Aliasing

Front 11

What type of velocities does color doppler report?

Back 11

Average/Mean Velocities

Front 12

What does RABT stand for?

Back 12

Red Away Blue Towards

Front 13

What does BART stand for?

Back 13

Blue Away, Red Towards

Front 14

What type of velocities does PW and CW doppler report?

Back 14

Peak Velocities

Front 15

In color doppler, the color represents what?

Back 15

Flow Direction

Front 16

What does black represent in color doppler?

Back 16

No doppler shift

Front 17

Colors above the black stripe represent blood cells moving in what direction?

Back 17

Toward the Transducer

Front 18

Colors below the black stripe represent blood cells moving in what direction?

Back 18

Away from the Transducer

Front 19

Flow toward the transducer is what kind of doppler shift?

Back 19

Positive Doppler Shift

Front 20

Flow away from the transducer is what kind of doppler shift?

Back 20

Negative Doppler Shift

Front 21

Colors closer to the black stripe represent what?

Back 21

Slower speeds

Front 22

Colors farther away from the black stripe represent what?

Back 22

Faster speeds

Front 23

In addition to direction and velocity, what additional information does variance mode offer?

Back 23

Laminar vs Turbulent Flow

Front 24

In variance mode, what do the colors on the left side represent?

Back 24

Laminar Flow

Front 25

In variance mode, what do the colors on the right side represent?

Back 25

Turbulent Flow

Front 26

In color doppler, multiple pulses are used to accurately determine blood velocities. What are these multiple pulses called?

Back 26

Packets
Ensembles

Front 27

The following advantages apply to what type of packets/ensembles?
- more accurate velocity measurements
- more sensitive to low flow

Back 27

Larger Packets
Longer Ensemble Lengths

Front 28

The following disadvantages apply to what type of packets/ensembles?
- more time needed to acquire data
- reduced frame rate
- decreased temporal resolution

Back 28

Larger Packets
Longer Ensemble Lengths

Front 29

Flows detected at angles closer to 0 degrees will be ___ than those detected closer to 60 degrees

Back 29

Brighter

Front 30

This modality only identifies the presence of a doppler shift, not speed or direction

Back 30

Power Doppler
Energy Mode
Color Angio

Front 31

In this modality, the strength/amplitude of the reflected signal is processed, which is directly related to the number of moving blood cells

Back 31

Power Doppler
Energy Mode
Color Angio

Front 32

What are 3 advantages of power doppler?

Back 32

1. increased sensitivity to low velocities
2. unaffected by doppler angles (unless 90 degrees exactly)
3. no aliasing

Front 33

What are 3 disadvantages of power doppler?

Back 33

1. no velocity or direction information
2. lower frame rates / temporal resolution
3. susceptible to motion / flash artifacts

Front 34

In addition to moving blood, very low frequency doppler shifts may be produced by ___ or ___

Back 34

Moving Anatomy
Pulsating Vessels

Front 35

On spectral displays, low frequency doppler shift artifacts called what?

Back 35

Clutter

Front 36

On color displays, low frequency doppler shift artifacts are called what?

Back 36

Ghosting

Front 37

How is clutter or ghosting eliminated?

Back 37

Wall Filter

Front 38

These exclude low frequency doppler shifts around the baseline, but have no effect on higher doppler frequency shifts commonly created by blood cell motion

Back 38

Wall Filters

Front 39

This is a special form of mirror image artifact that only appears with spectral doppler; while the flow pattern appears identical above and below the baseline, the true pattern in unidirectional

Back 39

Crosstalk

Front 40

The following cause what type of artifact?
- doppler receiver gain too high
- incident angle near 90 degrees between the beam and the flow direction

Back 40

Crosstalk

Front 41

This is the tool that breaks up a complex signal into the individual velocities which make up the reflected doppler signal

Back 41

Spectral Analysis

Front 42

This doppler analysis tool is exceedingly accurate and displays all individual velocity components from the reflected signal; it is used with PW and CW doppler

Back 42

FFT (Fast Fourier Transform)

Front 43

Using FFT, a laminar flow will produce what in the display?

Back 43

Spectral Window

Front 44

Using FFT, a turbulent flow will produce what in the display?

Back 44

Spectral Broadening

Front 45

When the spectral window is filled in, this is called what? and results from what?

Back 45

Spectral Broadening
Turbulent Flow

Front 46

This doppler analysis tool is less accurate but substantially faster than FFT; it is used with color flow doppler

Back 46

Autocorrelation
Correlation Function

Front 47

Can a patient be so severely anemic that a doppler exam cannot be performed?

Back 47

No

Front 48

Is FFT quantitative or qualitative?

Back 48

Quantitative

Front 49

Is autocorrelation quantitative or qualitative?

Back 49

Qualitative

Front 50

This ratio is a quantitative, doppler-derived measurement of the vascular resistance of a segment of the arterial system. It requires min/max velocities

Back 50

Resistivity Index (RI)

Front 51

This ratio is a quantitative, doppler-derived measurement of the vascular resistance of a segment of the arterial system. It requires min/mean/max velocities

Back 51

Pulsatility Index (PI)

Front 52

The following are advantages of what?
- based on mathematical measurements
- based on waveform shapes; unaffected by doppler angles

Back 52

Resistivity Index (RI)
Pulsatility Index (PI)

Front 53

The doppler effect is presented as a ___ when the source and the receiver are ___

Back 53

Frequency Shift
Moving relative to each other

Front 54

Starting from the same point, the sound source is moving east at 12 miles/hour and the receiver is moving west at 10 miles/hour. The doppler shift is ___

Back 54

Negative

Front 55

Starting from the same point, the receiver is moving west at 12 miles/hour and the source is moving west at 10 miles/hour. The doppler shift is ___

Back 55

Negative

Front 56

Doppler shift produces information about ___

Back 56

Velocity

Front 57

At what angle between the sound beam and the direction of motion will the doppler shift be at a maximum?

Back 57

0/180 degrees

Front 58

At what angle between the beam and the direction of motion will the doppler shift be a minimum?

Back 58

90 degrees

Front 59

What is the difference between speed and velocity?

Back 59

Speed = magnitude
Velocity = magnitude & direction

Front 60

What is the current method of processing doppler signals?

Back 60

FFT for spectral doppler
Autocorrelation for color doppler

Front 61

What is the typical range of doppler shift found in diagnostic imaging?

Back 61

20 Hz - 20 kHz (in the audible range)

Front 62

The phenomenon where high velocities appear negative is called what?

Back 62

Aliasing

Front 63

The frequency at which aliasing occurs is called what?

Back 63

Nyquist Limit

Front 64

The area of interrogation in a pulsed doppler exam is called what?

Back 64

Sample Volume

Front 65

T/F: the higher the emitted frequency, the more likely a pulsed wave signal is to alias

Back 65

T

Front 66

T/F: shallower sample volumes result in more aliasing

Back 66

F

Front 67

T/F: only pulsed wave doppler exams have a sample volume

Back 67

T

Front 68

An 8 MHz transducer with a PRF of 5,000 Hz is imaging to a depth of 7 cm. What is the Nyquist frequency?
A. 4 MHz
B. 3.5 Hz
C. 2.2 kHz
D. 2.5 dB
E. 5 kHz

Back 68

C

Front 69

An 8 MHz transducer with a PRF of 5,000 Hz measures a doppler shift of 7 kHz. The study is repeated with a 4 MHz transducer. What doppler shift will be measured?
A. 4 MHz
B. 3.5 Hz
C. 4 kHz
D. 3.5 dB
E. 3,500 Hz

Back 69

E