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ICMS > Diagnostic Imaging - Image Formation > Flashcards

Diagnostic Imaging - Image Formation Flashcards

1
Q

Ultrasound frequencies are above…

A

human hearing range

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2
Q

Velocity is

A

frequency x wavelength

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3
Q

There is an inverse relationship between

A

frequency and wavelength

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4
Q

ultrasound transducers are assembled in an

A

array

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5
Q

What is an array?

A

group of piezoelectric effects within transducer housing which causes currents to regenerate and produce images

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6
Q

Electric current causes crystal to resonate at a certain frequency emitting…

A

an ultrasound wave of that frequency where the amount of returning echo produces an image

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7
Q

Types of array determine…

A

the type of transducer

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8
Q

Linear array transducers have a …. and are great for…

A

straight surface
great for tendons or rectal scans

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9
Q

Curvilinear array transducers have a … surface, which increases…

A

curved, wider surface
increases surface area

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10
Q

Phased array transducers are… and have a smaller… making it great for viewing …

A

blockier
footprint
between the ribs

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11
Q

Why do we use gel when doing an ultrasound?

A

Sound cannot pass through air so gel is used as a coupling agent

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12
Q

What types of frequencies can be found in a transducer/probe?

A
  • single frequency
  • range of frequencies
  • multiple frequencies simultaneously
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13
Q

What happens to the ultrasound beam inside the patient?

A

Reflection
Refraction
Absorption

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14
Q

What is axial resolution?

A

the higher the frequency, the greater the resolution, the poorer the depth penetration

low frequency, lower resolution, better penetration

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15
Q

what is the most ideal for axial resolution?

A

use the highest MHz with the best resolution of the image created

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16
Q

Higher frequency means

A

a thinner beam which means better lateral resolution

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17
Q

The focal point is …

A

the narrowest area of beam making for better lateral resolution

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18
Q

After the focal point, the beam gets

A

wider, leading to worse resolution

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19
Q

What are the various modes of scanning?

A

A- mode (aptitude)
B-Mode (brightness)
M-mode (Motion)

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20
Q

In B-mode, the brightness is proportional to…

A

the strength of the echo

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21
Q

B-mode is used to evaluate…

A

tissue echotexture

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22
Q

Define: Anechoic

A

Without echoes
appears black

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23
Q

Define: hypoechoic

A

some echoes present
appears dark grey

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24
Q

Define: hyperechoic

A

large number of returning echoes
appears bright grey

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25
Q

What is M-mode?

A

time against motion

26
Q

When is M-mode commonly used?

A

to assess the contractility of the heart

27
Q

What are some of the common controls found on an ultrasound machine?

A

depth
frequency
power
gain
TGC (time gain compensation)
focus

28
Q

Depth on ultrasound allows you to

A

scan with the least depth of tissue between it and the transducer

29
Q

When should frequency be changed on ultrasound?

A

based on the depth of the tissue

30
Q

What does power control on ultrasound?

A

general brightness of an image

31
Q

higher power means

A

a stronger beam

32
Q

too high of power means there are

A

more artefacts w/ meaningless echoes displayed in the image

33
Q

too low of power means

A

the returning echoes are not strong enough to create an adequate image so the image is too dark

34
Q

Power does not…, it just…

A

change the beam itself
amplifies the signal of returning echoes.

35
Q

What does TGC do?

A

each slider controls signal amplification within the corresponding band in the image

36
Q

TGC can be adjusted to achieve

A

even brightness

37
Q

Altering the focus on ultrasound allows you to

A

focus an area of interest and improve resolution

38
Q

The focus is the …

A

narrowest point of the beam

39
Q

Narrower beam means

A

higher resolution

40
Q

What types of artefacts can be found on ultrasound?

A

reverberations
comet tails
acoustic shadowing
acoustic enhancement
edge shadowing
mirror image
side lobe artifact
other…

41
Q

What type of artefact is demonstrated here?

A

Reverberations

42
Q

What artefact is present here?

A

Comet tails

43
Q

What artefact is present here?

A

Acoustic Shadowing

44
Q

What artefact is present here?

A

Acoustic enhancement

45
Q

What artefact is present here?

A

Edge shadowing

46
Q

What artefact is present here?

A

Mirror image

47
Q

What artefact is present here?

A

Side lobe artefact

48
Q

What is doppler used for?

A

to measure movement, usually blood flow

49
Q

What are the different types of doppler?

A
  • color flow doppler
  • continuous wave
  • pulsed wave
  • power doppler
50
Q

What does color flow doppler show?

A

color-codes the direction of flow

51
Q

What type of doppler uses this? What does it mean?

A

Color-flow doppler
Blue away, red towards
blue takes longer to move away from you, red means it is coming towards you/the probe
Tells you the direction of the flow of blood

52
Q

When using color flow doppler, what can it measure?

A

how long it is expected for blood to move vs how long it actually takes.

53
Q

when using color flow doppler, what is important to remember?

A

you must have the probe pointed parallel to the blood flow you are looking at.

54
Q

Continuous wave doppler shows the

A

direction and velocity of flow

55
Q

pulsed wave doppler shows

A

the direction and velocity of lower velocity flow in a limited ‘gate’ area

56
Q

What type of doppler is demonstrated here?

A

Pulsed wave doppler

57
Q

What should you remember when using PW and CW dopplers?

A

blood flow velocity cannot be overestimated, only underestimated

58
Q

Power doppler shows

A

flow and movement

59
Q

power doppler is good for viewing

A

vascularity in tumors

60
Q

What is an exception to a power doppler?

A

it does not give velocity or direction, but rather that there is flow

61
Q

Which doppler has an audible sound?

A

Power doppler

ICMS (22 decks)

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