Ch. 17-20 Final Exam Review

Question 1

The energy at the beginning of the vessel must be __ than the energy at the end of the vessel for blood to flow.

Answer 1

Greater

Question 2

Contrast agents are used to improve image quality by changing the __ properties of the tissue that it resides in.

Answer 2

Acoustic

Question 3

What is characterized by chaotic flow patterns in many different directions and at many different speeds?

Answer 3

Turbulent flow

Question 4

Blood flows from regions of __ energy to __ energy.

Answer 4

High; low

Question 5

What imaging technique sends a positive and then a negative pulse down each scan line?

Answer 5

Pulse inversion harmonics

Question 6

Where are harmonics generated?

Answer 6

In tissue

Question 7

Resistance to blood flow is primarily controlled by __.

Answer 7

The radius of the vessel

Question 8

MI is proportional to ___ pressure.

Answer 8

Rarefactional

Question 9

MI is inversely proportional to __.

Answer 9

Frequency

Question 10

What uses the amplitude of the Doppler shift and the intensity of the red blood cells to be able to generate color on the image independent of the angle of insonation.

Answer 10

Power Doppler

Question 11

What form of Doppler has a large sample volume that obtains signals from all vessels within?

Answer 11

CW Doppler

Question 12

What is the best obtainable angle of insonation to produce the most accurate Doppler shift information?

Answer 12

60 degrees

Question 13

When is Doppler shift the highest?

Answer 13

When the beam angle is parallel to the direction of flow

Question 14

What is the smallest number of crystals a PW Doppler device may have?

Answer 14

One

Question 15

According to Bernoulli Principle, where will you find the highest velocity in a vessel with stenosis?

Answer 15

At the site of stenosis

Question 16

If blood pressure increases with no change in resistance, what happens?

Answer 16

Increased flow rate

Question 17

What is the type of blood flow typically visualized in arteries?

Answer 17

Pulsatile

Question 18

What type of blood flow is normally associated with veins?

Answer 18

Phasic

Question 19

A Reynolds number __ indicates turbulent flow on color Doppler evaluation.

Answer 19

Greater than 2000

Question 20

Resistance increases in a vessel:

Answer 20

Smaller vessels, increased viscosity, longer vessels, and closer to the vessel wall

Question 21

What happens when spectral Doppler gain is too high?

Answer 21

Overmeasurement of the velocities

Question 22

Which controls affect the amount of color fill in a vessel evaluated with color Doppler?

Answer 22

Color Doppler scale settings, sample size, and sample angle

Question 23

Does aliasing occur with color Doppler?

Answer 23

Yes

Question 24

The brightness of the reflection on the Doppler tracing represents __.

Answer 24

The number of red blood cells moving at each velocity displayed

Question 25

What type of blood flow is predicted with a Reynold's number less than 1500?

Answer 25

Laminar flow

Question 26

Which mathematical processing technique is used to analyze the data and produce a spectral waveform?

Answer 26

Fast Fourier Transform

Question 27

What does increasing the PRF/scale setting on spectral Doppler do?

Answer 27

Decreases the potential for aliasing

Question 28

Can color Doppler measure peak systolic and end diastolic velocities?

Answer 28

No

Question 29

In tissue harmonic imaging, what frequency is used to produce the image?

Answer 29

Double the fundamental frequency

Question 30

What is the term used to describe the cocentric layers of blood flow within a normal vessel.

Answer 30

Laminar flow

Question 31

As blood vessel radius decreases, __.

Answer 31

The resistance increases

Question 32

Pressure __, when a vein is fully expanded?

Answer 32

Increases

Question 33

What is the cosine of 60 degrees?

Answer 33

0.5

Question 34

What can you do to eliminate aliasing?

Answer 34

Increasing PRF, increasing the Nyquist limit above the frequency shift, and decreasing the sample depth

Question 35

What are the benefits of harmonic imaging?

Answer 35

Improves image quality, aids in visualization of borders, and lateral resolution improves

Question 36

No flow is detected while performing a color Doppler evaluation of a normal patient vein. What will improve the color display?

Answer 36

Increase the color packet size

Question 37

What is the cosine of 90 degrees?

Answer 37

0

Question 38

What does the brightness of the dots that make up the spectral display represent?

Answer 38

The number of red blood cells present

Question 39

What is the term used to describe the thickness of blood?

Answer 39

Viscosity

Question 40

What is the name of the flat flow profile that is seen at the entrance of vessels

Answer 40

Plug flow

Question 41

What is defined as the specific area or location where Doppler shift information is being obtained.

Answer 41

Sample volume

Question 42

Blood flow that varies with respiration is __.

Answer 42

Phasic

Question 43

What is an abnormality that would lead to an increase in the Reynolds number?

Answer 43

Stenosis of the vessel

Question 44

What are the advantages of CW Doppler over PW Doppler?

Answer 44

Not limited by PRF, no aliasing, and the ability to evaluate deeper vessels

Question 45

What is the signal processing technique used for color Doppler that is not as accurate as, but is faster than the technique used for spectral Doppler?

Answer 45

Autocorrelation

Question 46

Blood flow at a focal stenosis will demonstrate:

Answer 46

Increased resistance, increased velocity, and decreased pressure

Question 47

What must be increased in order to see an increase in flow volume?

Answer 47

Pressure difference

Question 48

During inspiration the flow in the veins of the upper extremities __.

Answer 48

Increases

Question 49

The speed of sound in soft tissue is __ related to the Doppler shift.

Answer 49

Inversely

Question 50

In a standing patient, where is the hydrostatic pressure the highest?

Answer 50

In the feet

Question 51

The Doppler shift is lowest at what angle to flow?

Answer 51

90 degrees

Question 52

What happens if blood flow is sampled in the center of laminar flow?

Answer 52

There will be a higher velocity than if sampled towards the edges

Question 53

What is the filling in of the spectral window on a Doppler tracing that is caused by turbulence?

Answer 53

Spectral broadening

Question 54

What is the Nyquist limit if the PRF is 5000 Hz?

Answer 54

2.5 kHz

Question 55

If the harmonic frequency is 10 MHz, what most likely is the fundamental frequency?

Answer 55

5 MHz

Question 56

In a vessel with a focal stenosis, where is the lowest pressure point found?

Answer 56

At the narrowest point in the vessel

Question 57

What is defined as the physiology of blood flow?

Answer 57

Hemodynamics

Question 58

The sonographer may avoid aliasing by altering the __.

Answer 58

Image depth

Question 59

What is the point at which Reynolds number predicts turbulence?

Answer 59

2000

Question 60

The harmonic signal __.

Answer 60

Is produced by the patient (tissues)

Question 61

When imaging in tissue harmonic imaging __.

Answer 61

The fundamental frequency is filtered out

Question 62

Flow moving away from the transducer will be demonstrated __.

Answer 62

Below the baseline

Question 63

The low velocity component is missing on a spectral waveform. What should be adjusted to fix this?

Answer 63

Wall filter

Question 64

What does Bernoulli's Principle describe?

Answer 64

In a stenosis, velocity increases and pressure decreases

Question 65

The Doppler shift is zero when the angle between the incident and the flow direction is __.

Answer 65

90 degrees

Question 66

When a reflector moves toward the transducer, what will happen to the reflected frequency?

Answer 66

It increases

Question 67

Blood flow moves in layers with the highest velocity layer in the center of the vessel describes __.

Answer 67

Parabolic flow

Question 68

The green or yellow color on the variance color map indicates __.

Answer 68

Turbulent flow

Question 69

With normal circulation, inspiration:

Answer 69

Increases venous return from the heart to the upper body

Question 70

How many crystals are needed for CW doppler devices?

Answer 70

At least two

Question 71

In an exercising patient, what is the response to peripheral resistance with arteriolar dilation?

Answer 71

The peripheral resistance decreases

Question 72

Artifacts related to propagation speed occur because:

Answer 72

The machine assumes 1,540 m/s for all tissue

Question 73

If the reflector is moving away from the sound source, the resulting reflected waves will exhibit:

Answer 73

A decrease in frequency

Question 74

In order to maintain flow as a constant, if the area of a vessel increases what must happen to the velocity?

Answer 74

It decreases

Question 75

When evaluating a suspected arterial stenosis, a Doppler angle of __ degrees will produce the MOST accurate flow velocity.

Answer 75

0

Question 76

What is a disadvantage of power Doppler?

Answer 76

Lack of information of blood flow direction

Question 77

In order to assess low velocity flow, what system adjustment should be made?

Answer 77

Decrease the rejection and wall filter setting

Question 78

The term __ refers to when all layers of blood flow are moving relatively the same speed.

Answer 78

Plug flow

Question 79

Assuming flow is constant, what happens in a region of blood vessel narrowing?

Answer 79

There is an increase in the velocity along with a corresponding decrease in pressure

Question 80

What type of energy relates to hydrostatic pressure?

Answer 80

Gravitational

Question 81

Intravascular contrast agents __ the reflectivity of selected tissues?

Answer 81

Increase

Question 82

Pulse inversion harmonic imaging __ spatial resolution and __ temporal resolution.

Answer 82

Increases; decreases

Question 83

Harmonic waves behave in a __ fashion.

Answer 83

Nonlinear

Question 84

Frequency will __ if the sound source and/or reflector move towards each other.

Answer 84

Increase

Question 85

Audible flow is termed __, while palpable flow is termed __.

Answer 85

Murmur or bruit; thrill

Question 86

Where does the blood travel the fastest when there is a stenosis?

Answer 86

In the stenosis

Question 87

Name the two types of laminar flow.

Answer 87

Plug and parabolic

Question 88

If the number of ultrasound pulses per scan lines increases:

Answer 88

The color packet size will increase

Question 89

Why does aliasing NOT occur with CW Doppler systems?

Answer 89

CW probes use two separate elements so they are not limited by pulse echo parameters like PRF and the Nyquist limit

Question 90

What system adjustment would increase the size of the spectral window?

Answer 90

Changing from 4 mm to 2 mm sample size

Question 91

What is a system adjustment that is made when changing from a lower extremity arterial exam to a lower extremity venous exam on the same patient?

Answer 91

Decrease doppler scale

Question 92

What will increase spectral broadening on the image?

Answer 92

Increases sample volume size

Question 93

Pulse inversion harmonics uses __ bandwidth transducers.

Answer 93

Wide

Question 94

Harmonics are __ the transducer frequency.

Answer 94

Twice

Question 95

Why do contrast agents reflect sound?

Answer 95

Because the impedance of the agent is different than the impedance of soft tissue