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Flashcards in Lesson 11 Deck (26)
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1

What does the reflection between 2 different boundaries depend on?

Media impedance

2

What is the result of a large difference between impedances?

A large reflection

3

What would happen if you injected air into a liver?

You would get a large reflection
- air vs solid

4

What are 2 examples of contrast agents?

1. Levovist
2. SonoVue

5

What are 4 characteristics of contrast agents?

1. Easy administration
2. Nontoxic
3. Stable
4. Small enough to perfuse through blood vessels (capillaries)

6

What do most contrast agents contain?

Microbubbles of air

7

What stabilizes contrast agents? (3)

1. Protein
2. Lipid
3. Polymer shell

8

What are contrast agents?

Dye that get injected to be bale to make structures more visible

9

How do reflections from blood show up as?

Weak echoes
- increases with contrast agents

10

What will high IRC show up as on an ultrasound?

As bright echoes

11

What do contrast agents produce?

Strong harmonics

12

When are harmonics produced?

When sound is produced non-linearly

13

What will introduction of contrast agents do with tissues?

Increase the echogenicity
- normally makes the tissue brighter and lesion darker, but can sometimes be the other way around

14

What is another use of contrast agents?

Perfusion rate

15

What can the ultrasound do at higher amplitudes to the bubbles?

Pop them

16

How is perfusion rate used in U/S?

Using high U/S to pop the bubbles and then using low amplitude to watch the organ fill back up

17

Perfusion rate

How fast the organ is getting blood back

18

What 2 pieces of information does the machine need to position the echo on display?

1. The direction the echo came from
2. The distance to the reflector/structure that created the echo

19

What can the transducer no do directly?

Measure distance

20

What does the transducer measure?

The travel time
- round trip

21

What is speed assumed to be?

1540m/s
- 1.54mm/us

22

What is the formula for distance?

Speed x Time

23

What is the formula for time?

Distance/Speed

24

What is the formula for speed?

Distance/Time

25

What is the formula for distance for range?

d = 1/2 v x t
d = 1/2 c x t

26

What is the round trip travel time in soft tissues?

13us/cm