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Assessment > Ultrasound > Flashcards

Ultrasound Flashcards

1
Q

Ultrasound is defined sound with a frequency above _____ Hz,

A

20,000 Hz

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2
Q

humans, the range of audible sound is between ___Hz and ___Hz

A

20 Hz and 2000 Hz

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3
Q

Diagnostic US typically operates in a range between __ and __ megaHz.

A

2 and 18 megaHz
(2,000,000 Hz and 18,000,000 Hz)

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4
Q

Which probe functions at higher frequencies to offer higher resolution but sacrifices imaging at deeper depths?
What would you use this for?

A

Linear (high frequency probe)
For superficial imaging just below skin surface.
* vessels
* muscles
* tendons
* breast
* thyroid

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5
Q

Which probe has a broad range of frencies to image anatomy needing a wider and deeper field of view? What might you use this probe for?

A

Curved/ Curvilinear (medium to low frequency)
* Adominal exam
* OB/Pelvic Exam

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6
Q

Which probe has a smaller footprint that allows for scanning in small spaces. Has lower frequency allowing for deeper imaging but sacrifices resolution for superficial structures.
used to scan?

A

Phased (medium to low frequency)
* between ribs
* cardiac scanning
* Can be used in abdomen as well

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7
Q

What is the pizoelectric element?

A

When an electric impulse is applied to the pizoelectric elements with in the transducer, they will begin to vibrate and produce sound waves that are transmitted through the body.
(he said, “ it converts electricity to sound waves)

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8
Q

frequency relates to wavelength how?

A

frequency and wavelength are inversely related

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9
Q

Deeper imagaing is seen with ____ frequency.

A

low

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10
Q

Superficial imaging is seen with ____ frequency.

A

High

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11
Q

Does the US probe have constant wave out put?

A

no it is in pulses because there is a listening period for returning signals

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12
Q

What does sound waves travel through fastest?

A

bones

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13
Q

what does sound waves travel through slowest?

A

air

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14
Q

increased density = ____ speed

A

decreased

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15
Q

increased stiffness = ______ speed

A

increased

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16
Q

How to choose an US probe?

A
  • consider type of block or procedure (superficial v deep)
  • patients habitus
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17
Q

What are three types of probes used for US exam?

A

Linear
Curvilinear
Phased array

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18
Q

Beam sweep of linear probe?

A

Will produce and image as wide as the probe

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19
Q

Beam sweep of curvilinear probe

A

will produce image wider than the probe

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20
Q

Phased array beam sweep?

A

Doesn’t have one. It has pizoelectric elements in the center of probe. Creates a cone shape field of view, so they have a smaller footprint but are good for tight space

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21
Q

Focal point

A

the point at which the beam is the narrowest and beam intensity is the greatest

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22
Q

Focal zone, what is best here?

A

the area around the focal point and the lateral resolution is best within this zone

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23
Q

Fraunhofer zone, also called?
location?
Lateral resolution?

A
  • Far field
  • the area distal to focal point
  • Beam within this field diverges and creates gaps with in the beam
  • lateral resolution is greatly reduced
24
Q

Frensel field also called?
Location?
Lateral resolution?

A
  • Near field
  • Area proximal to the focal zone
  • Beam starts out same width as probe but then narrows
  • Lateral resolution is good in this field
25
Q

Describe the different zone locations of the beam.

A
26
Q

What is impedance and what does it determine?
what is the equation for impedance?
increased tissue density = ___ impedence.

A

Impedance is the resistance to ultrasound propagation as it moves through a specific medium.
* Impedance = Density × propagation speed of the sound wave.
* If the density of a tissue increases the impedance increases as well.
* Impedance determines whether sound waves reflect, refract, or attenuate.

27
Q

What is US reflection?
Coefficient of 0?

A

The US waves that return to the probe
0= no reflection at all just keeps moveing through it

28
Q

What has highest US reflection?

A

Soft tissue - air (99)
Soft tissue- bone (66)

29
Q

What has lowest US reflection?

A

Fat - muscle (1.08)
Muscle-Liver (1.5)

30
Q

What is mirror artifact?

A

When tissue is mirrored on the other side of a structure.
(Ex/ diaphragm appears to be on other side of liver)

31
Q

What is refraction?
how can you fix it?

A
  • occurs when sound waves strike two adjacent mediums with slightly different impedance values.
  • This causes the propagation speed to change somewhat and the sound waves change direction.
  • Change angle and push in (heeling)
32
Q

what is edge artifact?

A

it is a result of refraction. which are the visualization of black lines that generate from the edge of rounded fluid filled structures such as cysts, bladder and vessels.

33
Q

What is attenuation?
is high or low frequency more effected?
What are the 3 main causes?

A
  • losing intensity and amplitude of sound waves as they travel through tissue
  • high frequency waves are more affected
  • reflection, refraction and absorption
34
Q

What is absorption?
are higher or lower frequency sound waves effected more?

A
  • when a sound wave loses energy as it travels through a medium
  • higher
35
Q

What is echogenicity?

A

ability to transmit or reflect US waves in the context of the surrounding tissues

36
Q

what is Anechoic?
what structures are anechoic?

A
  • structures that appear black, meaning that there are no internal echoes.
  • typical of fluid filled structures like cysts, gallbladder, urinary bladder, blood vessels, anterior chamber of the eye
37
Q

Hypoechoic?
examples?

A
  • structures appear darker than surrounding structures; gives off fewer echoes.
  • Often seen in tissues with increased density such as fibrous masses.
  • Kidney
  • spleen
  • NERVES
38
Q

Hyperechoic?
Examples?
what is hyperechoic sometimes called?

A
  • structures that appear brighter than surrounding structures; these structures give off more echoes.
  • BONES, fascia, tendons, fatty tumors
  • echogenic (meaning they possess a large number of echoes)
39
Q

Isoechoic?
Examples?

A
  • used to describe a structure that gives off similar echoes relative to another structure in the same image.
  • Kidney/liver
39
Q

Isoechoic?
Examples?

A
  • used to describe a structure that gives off similar echoes relative to another structure in the same image.
  • Kidney/liver
40
Q

Shadowing artifact?

A

vast majority of the sound waves that strike solids are reflected back to the transducer, but the remaining sound waves attenuate very quickly causing a shadow

41
Q

Posterior Acoustic Enhancement?

A

posterior acoustic enhancement is essentially the opposite of shadowing.
It occurs when sound waves pass through a structure with a very low attenuation coefficient (fluid filled structures).
Because sound passes through fluid filled structures exceptionally well, there is an increase in the brightness of posterior echoes.

42
Q

Reverberation?
In imaging of what structure is this useful in?

A

occurs in the presence of highly reflective surfaces.
sound strikes the reflector and essentially bounces back and forth between the reflector itself and the ultrasound transducer. This causes the image to record and display multiple evenly spaced echoes on the screen which are not real.
The lungs, because it creates A-lines, which help define the pleural line of the lung

43
Q

What is gain?

A
  • kind of like contrast.
  • helps compensate for attenuation.
44
Q

what is 2D or B-mode?

A

standard gray scale imaging

45
Q

What is M-mode?
When is this used?

A
  • Motion mode, motion vs time display of a B-mode image along a chosen line.
  • calculating fetal heart rate
  • Looking at lungs to see if there is a pneumo
46
Q

Color Mode?
Positive doppler shift
Blood flow toward probe?
Blood flow away from probe?
Problem with this mode?

A
  • used to assess blood flow through arteries and veins, or determine a vascular from a non-vascular structure
  • toward is Red
  • Away is blue
  • If you have the probe turned the wrong way blue will be toward and red will be away so have to make sure you are using probe correctly
47
Q
A

Sliding : moving along its long axis (left to right)

48
Q
A

Sweeping: moving the transducer along its short axis, (up and down)

49
Q
A

Tilting/ fanning: While maintaining a fixed position on the body, the transducer is moved along its short axis to change the angle of incidence < 90°.

50
Q
A

Rocking/heeling: While maintaining a fixed position on the body, pressure is applied to one side of the transducer to move in the long axis and reduce the incident angle < 90°.

51
Q
A

Rotating: Turning the transducer in a clockwise or counterclockwise direction over a fixed point on the body to change between a short and long axis view

52
Q

What type of block has a 90% chance of hoerners syndrome?

A

interscalene block

53
Q

What view is this short or long?

A

Short axis, in the transverse plane

54
Q

What view is this short or long axis?

A

Long axis in the longitudinal plane

55
Q

Out of plane is the same as?

A

Short axis, it gives a cross section sort of view

56
Q

In plane view is the same as?

A

Long axis view, longitudinal

Assessment (4 decks)

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