Ultrasound Physics Review 4

Front 1

While evaluating the liver vasculature with color doppler, you are unable to obtain signals from the deeper vessels, what should you do to enhance your ability to demonstrate flow in the deeper vessels?

Back 1

Decrease doppler frequency

Front 2

What is the maximum velocity limit for a 3MHz CW Doppler unit operating at a depth of 4cm: 40cm/s,200cm/s, 2.5m/s, 4m/s, none

Back 2

CW has range ambiguity so none

Front 3

Aliasing of the doppler spectrum occurs whenever the frequency shift exceeds what?

Back 3

1/2 the PRF

Front 4

During a hepatic sonogram using color doppler imaging, there is no color signal detected within the portal vein, what could you do to improve sensitivity to slow flow?

Back 4

Decrease the wall filter, Increase packet size, Increase color gain, Decrease the frequency

Front 5

The ensamble lenght in color doppler refers to the number of what?

Back 5

Pulses per scan line

Front 6

While performing a doppler study of the SMA, your measurement of the Doppler angle if incidence was underestimated, what error will result from this mistake?

Back 6

The velocity estimatio will be inacurate

Front 7

A commonly used process for determining the direction in a doppler instrument is what?

Back 7

Phase Quadrate Detection

Front 8

What method is used to steer the color beam with a linear array transducer?

Back 8

Elecrronic time delays

Front 9

When color doppler is active, how many pulses per scan line are used to create the underlying B-mode image

Back 9

One

Front 10

What doppler technique does not provide range resolution?

Back 10

CW doppler

Front 11

You have obtained a color doppler image of the common carotid artery after employing a red/blue map. WITHOUT using invert, if the frequency is greater than the transmitted frequency, which of the following would be correct: Color encoding red/negative doppler shift, color encoding blue/negative doppler shift, Color encoding red/positive doppler shift, color encoding blue/positive doppler shift, or No doppler shift?

Back 11

Color encoding red/positive doppler shift

Front 12

Ailiasing is a potential problem in PW doppler, why?

Back 12

Because of intermittent sampling

Front 13

What does the power spectrum depict?

Back 13

Relative importance of each frequency in the doppler signal

Front 14

What is the result of increasing the wall filter during doppler sampling?

Back 14

Reduce display of low frequency shifts

Front 15

You have increased the packet size while using color doppler to evaluate flow in the thyroid gland, what negative result will occur from this action?

Back 15

Decreased frame rate

Front 16

You have increased the packet size while using color doppler to evaluate flow in the thyroid gland, what negative result will occur from this action?

Back 16

Decreased frame rate

Front 17

What positive result will occur from the action taken when You increased the packet size while using color doppler to evaluate flow in the thyroid gland

Back 17

Improved signal to noise ratio

Front 18

What method is most commonly used to perform spectral analysis for pulsed doppler?

Back 18

FFT Fast Fourier Transform

Front 19

What is the doppler frequency shift defined as?

Back 19

The difference between the transmitted and recieved frequencies

Front 20

According to the doppler equation which of the following is not true: Increasing doppler frequency will increase the frequency shift, Increasing doppler interrogation angle will increase the frequency shift, Decreasing the reflector speed will decrease the frequency shift, No frequency shift is detected when the doppler beam strikes the reflector with perpendicular incidence, or Velocity information can be obtained from the frequency shift if the angle of incidence is known?

Back 20

Increasing doppler interrogation angle will increase the frequency shift is false.

Front 21

The Nyquist limit describes what?

Back 21

The aliasing frequency

Front 22

What information does the z axis (brightness) on the doppler spectrum provide?

Back 22

Amplitude

Front 23

A waveform in the ICA obtained at a doppler angle of 45degrees shows aliasing, which of the following choices will NOT help you to unwrap this waveform: Increase the angle of incidence, Decrease the high pass filter, Lower the zero baseline, Increase the PRF, or Decrease the doppler frequency

Back 23

Decrease the high pass filter

Front 24

While performing a color doppler exam in the abdomen you have adjusted several system controls and notice that the frame rate has decreased, which of the following adjustments can you make to improve the color frame rate: Increase the packet size, Decrease the PRF, Decrease the color box, Increase scan line density, or Increase the wall filter

Back 24

Decrease the color box

Front 25

You are performing a carotid duplex examination with the following: 5MHz doppler freq, 6KHz, 4cm depth, and a 1.5mm sample volume length, what is the aliasing frequency?

Back 25

3KHz, One half the PRF (OPERATING FREQUENCY 6KHz)

Front 26

The orapid technique used in most color doppler systems to obtain the mean soppler frequency shift is known as what?

Back 26

Autocorrelation

Front 27

What aspect of the doppler spectrum is color encoded with power doppler?

Back 27

Amplitude

Front 28

You have encountered spectral broadening of the ICA waveform, this most likely indicates what?

Back 28

Turbulent flow

Front 29

What term describes the number of pulses that are used to determine the velocity along a color line of sight?

Back 29

Packet size

Front 30

Which of the following methods will help you to demonstrate flow turbulence with color doppler: Autocorrelation, Variance, FFT, Zero crossing detection, or Phase quadrate detection?

Back 30

Variance

Front 31

What parameter describes the axial lenght of the sample volume for a color pixel?

Back 31

Color gate

Front 32

What type of Doppler device uses two transducers, one to reeive and one to transmit?

Back 32

CW doppler

Front 33

What is spectral analysis used to do?

Back 33

Determine the distribution and magnitude of frequency shifts in the reflected doppler signal

Front 34

Color flash artifact is obscuring the anatomy of interest in an exam of the Abd AO. What can you do to reduce the impact of the flash: Increase the color gain, Decrease the PRF, Increase the wall filter, Increase packet size, or Increase the doppler frequency?

Back 34

Increase the wall filter

Front 35

CW ultrasound can: sample specific areas, Sample a range of large areas, Can measure high velocities of blood flow, or has limitation of nyquist limit?

Back 35

It can measure high velocities of blood flow

Front 36

When the velocity of blood flow exceeds the doppler nyquist limit, what occurs?

Back 36

Aliasing

Front 37

An advantage of CW doppler over PW doppler is: Range resolution, Peak nyquist limit, Peak velocity detection, or Aliasing can be detected?

Back 37

Peak velocity detection

Front 38

When ultrasound waves travel through a medium which contains many small scatterers, the amount of sound that is scattered would do what?

Back 38

Increase sharply with increasing frequency

Front 39

The doppler shift frequency from moving reflectors is what?

Back 39

The difference between the transmitted and received ultrasonic frequencies

Front 40

Will Aliasing occur in: PW doppler, CW doppler, or Color doppler?

Back 40

PW and Color doppler, not CW doppler

Front 41

What factors are velocity calculations dependant on?

Back 41

Speed of sound in tissue, Doppler angle, and Transmitted frequency

Front 42

Color flow imaging utilizes what type of Doppler?

Back 42

PW doppler

Front 43

WAt what angle is the maximum doppler frequency shift detected?

Back 43

60 degrees

Front 44

The difference between the transmit frequency and the received frequency is called what?

Back 44

Doppler shift

Front 45

True or False: Aliasing is a diagnostic parameter for severe disease?

Back 45

False

Front 46

Power doppler is also referred to as what?

Back 46

Amplitude imaging

Front 47

Color flow doppler provides what type of velocity information?

Back 47

Average/Mean

Front 48

The Nyquist limit is equal to what?

Back 48

1/2 the PRF

Front 49

True or False: In laminar flow the blood is faster near the vessel walls?

Back 49

False

Front 50

No flow in a vessel would be indicated by what color?

Back 50

Black

Front 51

What is the simplified bernouli equation?

Back 51

4V2

Front 52

CW doppler utilizes how many elements?

Back 52

Two

Front 53

Color frame rate is affected by all of the following except what: Sector size, Color box size, Color gain, or PRF

Back 53

Colro gain

Front 54

What are the two catagories of energy that make up total fluid energy?

Back 54

Potential and kinetic energy

Front 55

What type of processing is utilized with most color flow systems?

Back 55

Autocorrelation

Front 56

True or False: Power doppler can detect flow direction?

Back 56

False

Front 57

Power mode differes from color dopppler by evaluating what?

Back 57

The amplitude of the signal

Front 58

Window filling of the spectral tracing is due to what?

Back 58

Turbulent flow, Sample gate too large, SV placed too close to the vessel wall, Gain to high

Front 59

What angle provides the maximum doppler shift angle?

Back 59

Zero

Front 60

All of the following are true regarding power doppler except which: Greater sensitivity than color doppler, Doppler angle has little effect on flow detection, slower image rates, or less flash artifact?

Back 60

Less flash artifacts

Front 61

What do you expect to see with a high reynolds number?

Back 61

Turbulent flow

Front 62

True or False: Blood flow is most turbulent proximal to a stenosis?

Back 62

False

Front 63

True or False: A minimum of 3 pulses per scan line is required to assign color?

Back 63

True

Front 64

True or False: Vascular resistance is determined by the radius of the blood vessel?

Back 64

True

Front 65

There is no turbulence of blood whan the Reynolds number is less than what?

Back 65

2000

Front 66

True or False: Potential energy may be increased when blood changes speed and direction?

Back 66

False

Front 67

What color assignment to flow towards the transduce?

Back 67

Red

Front 68

What are the units of measure for doppler shift?

Back 68

KHz

Front 69

True or False: Color aliasing is seen when the red and blue are seperated by black?

Back 69

False

Front 70

What is the minimum number of pulses required for color to be displayed using autocorrelation technique?

Back 70

3

Front 71

True or False: Color dopppler has less velocity information than spectral doppler?

Back 71

True

Front 72

All of the following are true regarding color doppler except: Color doppler will not alias, color doppler is qualitative data, color doppler is a pulse doppler technique, or color doppler uses autocorrelation processing?

Back 72

Color doppler will not alias is flase

Front 73

True or False: The return signal in color doppler is an average of the signals from many blood cells?

Back 73

True

Front 74

Which technique allows the display of amplitude signals from the blood cells?

Back 74

Power doppler

Front 75

True or False: Amplitude imaging takes a long time to process compared to color doppler?

Back 75

True

Front 76

All are true regarding amplitude imaging except: It is a quantitative technique, it has good sensitivity to slow flow, it is not angle dependent, or it can not display direction of flow?

Back 76

It is a quantitavie technique is false

Front 77

The amplitude of returning signals is dependent upon which factors?

Back 77

Density of RBCs, blood/tissue signal separation, size of vessels in relation to sample volume size, attenuation

Front 78

Low velocity high amplitude signals can be eliminated from spectral tracing how?

Back 78

By use of the wall filter

Front 79

Lowering the doppler transmit frequency will provide increased penetration and will provide what type of reflected frequency shifts?

Back 79

Smaller

Front 80

Reflections from the blood are known as what?

Back 80

Rayleigh scattering

Front 81

True or False: Color doppler does not display mean frequency, direction of flow and turbulence

Back 81

False

Front 82

True or False: Spectral doppler displays flow direction turbulence and peak velocity information?

Back 82

True

Front 83

True or False: Power doppler displays existence of flow but no direction information?

Back 83

True

Front 84

Is Vascular resistance: Directly, Inversely, Logithimically, or not proportional to the radius of the vessel?

Back 84

Directly

Front 85

The flow of blood through the body is affected by which of the following factors: Density, Size of the vessel, pressure gradient, or all of them

Back 85

All of them

Front 86

What is the difference between FFT and autocorrelation doppler techniques?

Back 86

Autocorrelation can olnly provide mean values of doppler shift

Front 87

In order to increase the Nyquist limit and correct aliasing you would: Increase PRF, not change PRF, or Decrease PRF?

Back 87

Increase PRF

Front 88

The color image and spectrum analysis provided are indicative of a high grade stenosis because of what?

Back 88

Elevated peak velocity and post stenotic turbulence

Front 89

By increasing the doppler angle between the incident beam and the direction of blood flow, the result would be an increase in what?

Back 89

Increased potential for error in calculating velocity

Front 90

Which statement is not true regarding color doppler imaging: color doppler requires a min of 3 pulses per scan line, color doppler can alias and has limitations, color doppler is a quantitative technique, or color doppler utilizes PW doppler?

Back 90

Color doppler is a quantitative technique