Intro to Ultrasound

Question 1

What is ultrasound

Answer 1

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

Question 2

What is the diagnostic ultrasound frequency?

Answer 2

1-30megaHz

Question 3

What are the physics of ultrasound?

Answer 3

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

Question 4

What is the propagation velocity of ultrsound waves?

Answer 4

1540m/sec

Question 5

What is the equation for ultrasound physics?

Answer 5

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

Question 6

What is the equation for velocity?

Answer 6

velocity= frequency (f) x wavelength

Question 7

Wavelength

Answer 7

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

Question 8

Frequency

Answer 8

cycles per second (hertz, Hz)

Question 9

Why are wavelength and frequency important?

Answer 9

Higher frequency gives higher resolution but lower penetration

Lower frequency gives lower resolution but deeper penetration

Question 10

Attenuation

Answer 10

loss of ultrasound

Question 11

What increases attenuation?

Answer 11

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

Question 12

What has a low acoustic impedance?

Answer 12

Air

Question 13

What has a high acoustic impedance?

Answer 13

Bone

Question 14

Acoustic Impedance

Answer 14

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

Question 15

What are the artifacts of ultrasound?

Answer 15

Acoustic shadowing 
Acoustic enhancement 
Edge shadowing 
Reverberation artifact 
Slice thickness artifact 
Mirror image artifact

Question 16

Acoustic Shadowing

Answer 16

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

Question 17

Clean Acoustic Shadowing

Answer 17

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

Question 18

Dirty Acoustic Shadowing

Answer 18

99% of the sound wave gets reflected

Acoustic shadow is dirty (inhomogenous/reverberation artifact)

Question 19

What causes Clean Acoustic Shadowing?

Answer 19

Bone

Plastic

Question 20

What causes Dirty Acoustic Shadowing?

Answer 20

Air

Question 21

Acoustic Enhancement

Answer 21

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

Question 22

Edge Shadowing

Answer 22

Small shadow at the edge of round structures

Question 23

Slice Thickness Artifact

Answer 23

at curved surfaces the machine averages

Question 24

Mirror Image Artifact

Answer 24

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

Question 25

What are the three types of transducers?

Answer 25

Liner Sector Convex

Question 26

What is in the transducer that emits and receives?

Answer 26

Peizoelectric-crystals

Question 27

How do you prepare a patient for an ultrasound?

Answer 27

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

Question 28

Where do you place the ultrasound machine and examiner?

Answer 28

on the left side of the table

Question 29

Where is the direction of the dog's head?

Answer 29

in the direction of the machine

Question 30

What are the two planes of scanning?

Answer 30

Sagittal or dorsal plane | Transverse plane

Question 31

Anechoic

Answer 31

homogenous black | Ex: Fluid

Question 32

Hypoechoic

Answer 32

Less echoic than other structures | "Darker" than other structures

Question 33

Isoechoic

Answer 33

"Same" echogenicity as another structure

Question 34

Hyperechoic

Answer 34

Higher echogenicity than other structures | "Brighter"

Question 35

Normoechoic

Answer 35

Returning signal as expected for this organ

Question 36

Compressible

Answer 36

Does it disappear with pressure

Question 37

Invaded

Answer 37

Tumor that is infiltrating the surrounding tissue

Question 38

What is the pneumonic for increasing echogenicity?

Answer 38

My Cat Loves Sunny Places

Question 39

Anechoic

Answer 39

Transudate

Question 40

Speckled/more echogenic

Answer 40

exudate, blood, chyle