Maverick Modules 11-16

Question 1

What is sound?

Answer 1

Series of repeating pressure waves that propagate through a medium
sound is mechanical

Question 2

How is sound measured?

Answer 2

pressure wave frequency (Hz) which is cycles per second

Question 3

What are the Hz frequencies for US?

Answer 3

2MHz - 20MHz

Question 4

What do high and low frequency probes image?

Answer 4

• High frequency probes images superfically
• Low frequency probes images deep

Question 5

you can have anywhere between ____ and ____ crystals in your transducer

Answer 5

128-512 (the more crystals will give you a sharper image)

Question 6

What are the acoustic impedance views of different materials?

Answer 6

Impedance is the measure of a material’s tendancy to transmit sound waves

Question 7

Structures with high propagation velocity will appear ____ in the US image

Answer 7

white

Question 8

Acoustic impedance is impacted by the ____ and ____ of the material

Answer 8

elasticity and density

Question 9

Homogeneous mediums reflect ____ sound

Answer 9

No sound is reflected (homogeneous like fluid)

Question 10

Loss of signal is also known as

Answer 10

attenuation

Question 11

What attenuation principle is depicted below?

Answer 11

Absorption

Question 12

What attenuation principle is depicted below?

Answer 12

Reflection

Question 13

What attenuation principle is depicted below?

Answer 13

Scattering

Question 14

What attenuation principle is depicted below?

Answer 14

Refraction

Question 15

What three factors affect how tissues reflect ultrasound waves?

Answer 15

• Acoustic Impedance Mismatch
• Angle of Insonation
• Smoother or Specular Reflections

Question 16

What is Anisotropy?

Answer 16

Objects that are 90 degrees to the US beam generate the best reflection

Question 17

Which angle below will give a better image of the nerve?
Why?

Answer 17

A2 due to Angle of Insonation (we want 90 degree angle of the structure, not the skin)

Question 18

What is “toeing in”?

Answer 18

this will make your probe and needle parallel to one another so the US beam is perpendicular to the needle
- you get a stronger reflection from the needle and weaker from the target

Question 19

What’s the most important safety tip when utilizing ultrasound?

Answer 19

Always see the needle tip

Question 20

Do we want a shallow or deep approach with our needle to see it with US the best?

Answer 20

Shallow, the more parallel the angle of insonation is, the more needle we see with the US

Question 21

What type of reflection is noted below?

Answer 21

Specular Reflection (large smooth surfaces reflect sound like a mirror)

Question 22

What type of reflection is noted in the image below?

Answer 22

Diffuse Reflection (bumpy surfaces change the way the sound is reflected b ack)

Question 23

What types of tissue/material are typically responsible for acoustic shadowing?

Answer 23

• Bones
• Calcifications
• Gas

Question 24

What type of material is typically responsible for posterior acoustic enhancement?

Answer 24

Homogenous Liquids (Cysts typically let the sound pass directly through it and have no reflection)

Question 25

What is Gain Artifact?

Answer 25

too much signal bouncing around and the picture appears very hyperechoic

Question 26

What artifact indicates that the ultrasound probe is perfectly parallel with your needle?

Answer 26

Needle Reverberation Artifact
- result of multiple echos or reflections from the delay of an echo before returning to the transducer
- parallel and in plane US beam

Question 27

Which axis is the most commonly used for nerve blocks?

Answer 27

Short axis view (transverse view)

Question 28

Instead of “find your needle” what should we do?

Answer 28

Make the needle find your beam