Deck 5: Doppler Principles

Question 1

The difference between the emitted frequency and the echo frequency returning from a moving scatterer is called ________.

A) Doppler effect
B) Doppler shift
C) continuity rule
D) Bernoulli effect

Answer 1

B
The change in frequency caused by motion is called the Doppler shift or Doppler shift frequency.

Question 2

The Doppler equation relates the Doppler shift to the ________.

A) pressure and resistance
B) flow speed and frequency
C) flow speed and pressure
D) flow speed and resistance

Answer 2

B
The Doppler equation relates the Doppler shift to the flow speed and the frequency.

Question 3

Sound reflects totally at the wall-blood boundary once the Doppler angle is less than ________ degrees.

A) 30
B) 40
C) 50
D) 60

Answer 3

A
At a Doppler angle less than 30 degrees,the sound no longer enters the blood at all but is reflected totally at the wall-blood boundary.

Question 4

Resistance to flow offered by a fluid in motion describes ________.

A) velocity
B) pressure
C) viscosity
D) volumetric flow rate

Question 5

The volumetric flow rate is equal to ________.

A) pressure difference multiplied by the resistance
B) resistance of blood flow multiplied by the flow rate
C) average flow rate across the vessel multiplied by the cross-sectional area of the vessel
D) force per unit area

Question 6

Which matter is considered a fluid?

A) Gases.
B) Solids.
C) Liquids.
D) Gases and liquids.

Question 7

Turbulent flow is a form of ________ flow.

A) pulsatile
B) continuous
C) parabolic
D) nonlaminar

Question 8

A nonsteady flow with acceleration and deceleration over the cardiac cycle,is called ________.

A) plug flow
B) pulsatile flow
C) laminar flow
D) parabolic flow

Question 9

For a given flow,the greater the Doppler angle,the ________.

A) less the Doppler shift
B) higher the operating frequency
C) lower the speed of the scatterer
D) more accurate the Doppler information

Question 10

Doppler shift does not depend on the ________.

A) flow speed
B) flow direction
C) operating frequency
D) Doppler angle

Question 11

Gases,nutrients and waste products are exchanged through the walls of ________.

A) arteries
B) venules
C) arterioles
D) capillaries

Question 12

What is required for flow to occur?

A) Hydrostatic pressure
B) Pressure difference
C) Constant driving pressure
D) Variable driving pressure

Question 13

________ are the tiniest vessels in the human body.

A) Veins
B) Venules
C) Arterioles
D) Capillaries

Question 14

The state of the downstream arterioles is reflected in the ________.

A) arterial peak systole
B) arterial diastolic flow
C) venous flow rate during expiration
D) venous flow rate during inspiration

Question 15

________ describes the volumetric flow rate as a constant.

A) Bernoulli effect
B) Continuity rule
C) Poiseuille's law
D) Doppler equation

Question 16

If pressure differences in a straight vessel increase,the flow rate ________.

A) increases
B) decreases
C) does not change
D) changes direction

Question 17

The decreased pressure in regions of high flow speed is called ________.

A) Poiseuille's law
B) Bernoulli effect
C) continuity rule
D) volumetric flow rate

Question 18

What type of blood flow demonstrates layers of fluid sliding over each other?

A) Plug.
B) Helical.
C) Disturbed.
D) Laminar.

Question 19

Resistance of the blood flow depends on the radius of the ________.

A) tube to the fourth power
B) tube squared
C) tube divided by the length of the tube
D) tube

Question 20

What is the driving force behind blood flow?

A) Heart.
B) Gravity.
C) Pressure.
D) Flow rate.

Question 21

The amount of blood passing a point per unit of time defines ________.

A) velocity
B) viscosity
C) resistance
D) volumetric flow rate

Question 22

The fast Fourier transform derives the Doppler ________.

A) color scale
B) spectrum
C) variance maps
D) power display

Question 23

Which of the following Doppler techniques must be time shared?

A) Color Doppler
B) Duplex imaging
C) Spectral analysis
D) Continuous wave

Question 24

A Doppler shift at 60 degrees is ________ what it would be at 0 degrees.

A) twice
B) one half of
C) three times
D) two thirds of

Question 25

Which flow type demonstrates a flow velocity that is essentially constant across the vessel?

A) Plug
B) Helical
C) Laminar
D) Parabolic

Question 26

The horizontal presentation in the spectral display represents ________.

A) time
B) velocity
C) imaging depth
D) acceleration time

Question 27

The angle of incidence is not important with which Doppler display?

A) Color
B) Power
C) Duplex
D) Spectral

Question 28

The resistance of the ________ accounts for about one half of the total resistance in the systemic circulation.

A) blood flow
B) flow rate
C) arterioles
D) capillaries

Question 29

With color Doppler imaging,the priority control ________.

A) eliminates aliasing
B) filters out low-intensity echoes
C) selects the pulse repetition frequency
D) selects which gray-scale echo strength will demonstrate color

Question 30

Doppler measurements are not reliable at Doppler angles greater than ________ degrees.

A) 30
B) 40
C) 50
D) 60

Question 31

Variance color maps demonstrate a change of hues from ________.

A) left to right
B) right to left
C) bottom to top
D) top to bottom

Question 32

A change in frequency caused by motion of a source or reflector defines ________.

A) Doppler shift
B) Doppler effect
C) spectral analysis
D) Poiseuille's equation

Question 33

Which type of blood flow demonstrates a chaotic flow pattern?

A) Stenotic
B) Disturbed
C) Parabolic
D) Turbulent

Question 34

Which type of blood flow would demonstrate the narrowest range of Doppler shift frequencies?

A) Plug
B) Laminar
C) Parabolic
D) Disturbed

Question 35

Spectral broadening may be produced by ________.

A) low flow velocities
B) high wall filter settings
C) beam spreading in arrays
D) low Doppler gain settings

Question 36

The maximum normal flow speed in the circulation is ________ cm/s.

A) 75
B) 80
C) 100
D) 125

Question 37

Which system control eliminates low-frequency Doppler shifts?

A) Range gate
B) Wall filter
C) Dynamic range
D) Angle correction

Question 38

Vertical thickening of the spectral tracing is called ________.

A) turbulence
B) range ambiguity
C) Doppler effect
D) spectral broadening

Question 39

The width of the sample volume is determined by the ________.

A) beam width and sample volume depth
B) operating frequency and maximum penetration depth
C) thickness of the element and sample volume depth
D) number of focal zones utilized and maximum penetration depth

Question 40

What advantage does spectral analysis have when compared to other Doppler techniques? Spectral analysis ________.

A) is not angle dependent
B) is free of aliasing artifact
C) determines flow direction
D) displays peak systolic velocities

Question 41

Blood flows from the left and right ventricles into the aorta and pulmonary artery,respectively.

Question 42

Determining the direction of the Doppler shift voltages is accomplished by the ________.

A) autocorrelation
B) spectrum analyzer
C) fast Fourier transform
D) phase quadrature detector

Question 43

Continuous-wave Doppler shifts are detected within the ________.

A) range gate
B) near zone length
C) region of the transmitting beam
D) overlapped region of the transmitting and receiving beams

Question 44

The Doppler shift is proportional to the blood flow speed.

Question 45

In a stenosis,flow speed increases and pressure decreases.

Question 46

Which of the following pulsed Doppler techniques is the most likely to demonstrate slow flow velocities in deep vessels?

A) Color Doppler.
B) Duplex imaging.
C) Power Doppler.
D) Spectral analysis.

Question 47

Poiseuille's equation states that,if the flow rate increases,the ________.

A) tube length has increased
B) tube diameter has increased
C) pressure difference has decreased
D) viscosity of the fluid has increased

Question 48

Motion toward the transducer demonstrates ________.

A) spectral broadening
B) flow below the baseline
C) a positive Doppler shift
D) an antegrade flow pattern

Question 49

Poise is a unit given for ________.

A) density
B) velocity
C) viscosity
D) pressure

Question 50

Echoes arrive from the sample volume depth at a rate equal to ________.

A) the pulse repetition frequency
B) twice the pulse repetition frequency
C) one half of the pulse repetition frequency
D) one quarter of the pulse repetition frequency

Question 51

Volumetric flow rate is proportional to flow resistance.

Question 52

If the pressure difference between two points increases,the flow rate also increases.

Question 53

If the length of the tube increases,the flow rate also increases.

Question 54

Poiseuille's law deals with a long straight vessel without stenosis.

Question 55

The normal adult circulatory system contains ________ liters of blood.

A) 3
B) 4
C) 5
D) 6

Question 56

Disturbed flow is a form of laminar flow.

Question 57

The maximum detectable blood flow speed with pulsed Doppler imaging is determined by aliasing.

Question 58

Which of the following is an advantage of pulsed Doppler?

A) Sensitivity of low flow velocities is increased.
B) Higher operating frequencies can be utilized.
C) Depth of sample volume can be accurately selected.
D) Higher frequency shifts can be displayed without aliasing.

Question 59

According to Poiseuille's equation,if the radius of the tube increases,flow rate increases.

Question 60

Which of the following Doppler displays cannot determine flow direction?

A) Color
B) Power
C) Spectrum
D) Continuous wave

Question 61

If viscosity increases,flow rate increases.

Question 62

As flow energy increases,pressure energy increases.

Question 63

Power Doppler shifts are determined by the speed of the moving scatterers.

Question 64

In pulsed Doppler imaging,the operator of the ultrasound system controls the length and location of the sample volume.

Question 65

Increased flow speed through a stenosis can cause distal turbulence.

Question 66

Color Doppler displays utilize high frame rates.

Question 67

The Doppler shift is directly related to volumetric flow rate,not the flow speed.

Question 68

Pulsatile flow is uncommon in arterial circulation.

Question 69

If the source frequency increases,the Doppler shift increases.

Question 70

If the flow speed increases,the pressure decreases.

Question 71

Flow conditions downstream can be reflected in the spectral analysis slightly upstream.

Question 72

A decrease in pressure in regions of high flow speed is called the Poiseuille's effect.

Question 73

The variation in colors in different locations is caused by the changing Doppler angle.

Question 74

Higher operating frequencies produce larger Doppler shifts.

Question 75

Multiple foci are used in color Doppler imaging.