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RUSVM Diagnostic Imaging 2016 > Intro to Ultrasound > Flashcards

Intro to Ultrasound Flashcards

1
Q

What is ultrasound

A

High frequency sound waves beyond the range of human hearing (20Hz-20 kilohertz)

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2
Q

What is the diagnostic ultrasound frequency?

A

1-30megaHz

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3
Q

What are the physics of ultrasound?

A

Mechanical energy as sound waves are transmitted through a patient and returning echoes are detected

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4
Q

What is the propagation velocity of ultrsound waves?

A

1540m/sec

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5
Q

What is the equation for ultrasound physics?

A

Acoustic impedance (z) = velocity (v) X tissue density (p)

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6
Q

What is the equation for velocity?

A

velocity= frequency (f) x wavelength

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7
Q

Wavelength

A

Distance between one peak or trough and the next peak or trough (mm)

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8
Q

Frequency

A

cycles per second (hertz, Hz)

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9
Q

Why are wavelength and frequency important?

A

Higher frequency gives higher resolution but lower penetration

Lower frequency gives lower resolution but deeper penetration

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10
Q

Attenuation

A

loss of ultrasound

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11
Q

What increases attenuation?

A

Increased distance from the transducer
Less homogenous medium to traverse due to increased acoustic impedance
Higher frequency (shorter wavelength) transducers

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12
Q

What has a low acoustic impedance?

A

Air

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13
Q

What has a high acoustic impedance?

A

Bone

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14
Q

Acoustic Impedance

A

characteristic of the propagation medium
a reflected sound wave is generated at the interface of an impedance mismatch
no reflections occur in a homogenous medium

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15
Q

What are the artifacts of ultrasound?

A 
Acoustic shadowing 
Acoustic enhancement 
Edge shadowing 
Reverberation artifact 
Slice thickness artifact 
Mirror image artifact
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16
Q

Acoustic Shadowing

A

Distal to highly reflective objects
Interface absorbs or reflects entire sound
Results in an anechoic area

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17
Q

Clean Acoustic Shadowing

A

at the tissue-bone interface
complete absence of reverberation artifacts
homogenous anechoic shadow produced

18
Q

Dirty Acoustic Shadowing

A

99% of the sound wave gets reflected

Acoustic shadow is dirty (inhomogenous/reverberation artifact)

19
Q

What causes Clean Acoustic Shadowing?

A

Bone

Plastic

20
Q

What causes Dirty Acoustic Shadowing?

A

Air

21
Q

Acoustic Enhancement

A

Fluid of homogenous acoustic impedance attenuates less sound than the surrounding tissue

22
Q

Edge Shadowing

A

Small shadow at the edge of round structures

23
Q

Slice Thickness Artifact

A

at curved surfaces the machine averages

24
Q

Mirror Image Artifact

A

At highly reflective air/fluid interfaces a false image is produced on the other side of the reflector

25
Q

What are the three types of transducers?

A

Liner
Sector
Convex

26
Q

What is in the transducer that emits and receives?

A

Peizoelectric-crystals

27
Q

How do you prepare a patient for an ultrasound?

A 
12 hour fasting 
Free access to water
Avoid stress --> Aerophagia
Shave fur
Dorsal recumbency
28
Q

Where do you place the ultrasound machine and examiner?

A

on the left side of the table

29
Q

Where is the direction of the dog’s head?

A

in the direction of the machine

30
Q

What are the two planes of scanning?

A

Sagittal or dorsal plane

Transverse plane

31
Q

Anechoic

A

homogenous black

Ex: Fluid

32
Q

Hypoechoic

A

Less echoic than other structures

“Darker” than other structures

33
Q

Isoechoic

A

“Same” echogenicity as another structure

34
Q

Hyperechoic

A

Higher echogenicity than other structures

“Brighter”

35
Q

Normoechoic

A

Returning signal as expected for this organ

36
Q

Compressible

A

Does it disappear with pressure

37
Q

Invaded

A

Tumor that is infiltrating the surrounding tissue

38
Q

What is the pneumonic for increasing echogenicity?

A

My Cat Loves Sunny Places

39
Q

Anechoic

A

Transudate

40
Q

Speckled/more echogenic

A

exudate, blood, chyle

RUSVM Diagnostic Imaging 2016 (27 decks)

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