Harmonics and Contrast Agents

Question 1

What is fundamental frequency?

Answer 1

frequency created by the transducer.

Question 2

What is harmonic frequency?

Answer 2

2x’s the fundamental frequency.

Question 3

How does harmonic frequency happen?

Answer 3

during nonlinear behavior

Question 4

What is fundamental imaging?

Answer 4

created by processing reflections that have the same frequency as transmitted sound.

Question 5

What are harmonic images?

Answer 5

Images created by processing reflections the are twice the fundamental frequency.

Question 6

What are 2 forms of harmonics?

Answer 6

1. Tissue harmonics
2. contrast harmonics

Question 7

Why is harmonic imaging helpful?

Answer 7

helps improve poor quality images, because harmonic frequency waves undergo less distortion.

Question 8

What does linear behavior mean?

Answer 8

proportional, linear systems respond in an even manner.

Question 9

What does nonlinear behavior mean?

Answer 9

Irregular, behaves unevenly.

Question 10

When are harmonics frequency created?

Answer 10

During transmission

Question 11

What is tissue harmonics?

Answer 11

The minuscule amount of energy is converted from fundamental frequency to harmonic frequency.

Question 12

Fundamental imaging will have what?

Answer 12

Lower quality imaging and have more noise.

Question 13

What is the significance of the gradual development of a harmonic signal?

Answer 13

The minuscule amount of energy that converts from fundamental frequency to harmonic frequency.

Question 14

Tissue harmonics do not exist where?

Answer 14

Superficial depths.

Question 15

What are some advantages of tissue harmonics?

Answer 15

1. improve signal to noise ratio

Question 16

Weak beams do not create what?

Answer 16

Tissue harmonics

Question 17

True of False, Harmonic strength weakens as it propagates deeper in the body?

Answer 17

True

Question 18

Where is the beam strongest?

Answer 18

At the focus, along the beams main axis.

Question 19

True or false, Harmonics are present as they leave the transducer?

Answer 19

False

Question 20

Narrow bandwidth creates degraded what?

Answer 20

Spatial resolution

Question 21

What is pulse inversion harmonic technique?

Answer 21

2 beams at 180 degrees out of phase completely deconstruct, leaving harmonic signal that the original resonant frequencies create.

Question 22

What is a disadvantage of pulse inversion harmonics?

Answer 22

frame rate is halved.

Question 23

What is power modulation?

Answer 23

Where during reception, the reflections from the first pulse is doubled then subtracted from the weaker second wave, completely canceling each other out.

Question 24

What are some advantages of power modulation?

Answer 24

1.less distortion
2. better spatial resolution

Question 25

Why is it so significant that only strong sound beams create harmonic signals?

Answer 25

creates less distortion and less noise.

Question 26

contrast agents are also known as what?

Answer 26

microbubbles

Question 27

Contrast agents meet what 5 requirements?

Answer 27

1. safe 2. metabolically inert 3. long lasting 4. strong reflector of ultrasound 5. small enough to pass through capillaries

Question 28

When is contrast harmonics created?

Answer 28

during reflection

Question 30

What is resonance?

Answer 30

the contraction and expansion of microbubbles

Question 31

Saline bubble study is used to evaluate what?

Answer 31

The right side of the heart.

Question 32

Contrast agents or micro bubbles are used to evaluate what?

Answer 32

the left side of the heart.

Question 33

What is the goal of using contrast agents?

Answer 33

to create a reflection that helps to delineate the left ventricle wall from blood.

Question 34

True or false, micro bubbles act in a nonlinear manner when struck by sound?

Answer 34

True

Question 35

True or false, the impedance of the contrast agent is the same as the impedance of soft tissue?

Answer 35

False, it is different.

Question 36

What expands the bubble in a contrast agent?

Answer 36

Peak rarefactions expand the bubble.

Question 37

True or False, grating lobes are capable of producing harmonic signals?

Answer 37

False

Question 38

The purpose of power modulation harmonic imaging is to.....?

Answer 38

Double and then subtract from the second reflection to remove the fundamental frequency.

Question 39

Within the first 2cm of tissue harmonics does not exist.

Answer 39

False

Question 40

What is the name of the image that processes reflections at the same frequency as the transmitted (or resonant) frequency?

Answer 40

Fundamental image

Question 41

True or False, tissue harmonics are created during harmonics?

Answer 41

True

Question 42

Agitated saline bubble contrast agents are used for:

Answer 42

Right side evaluation for shunts.

Question 43

The meaning of resonance with microbubbles contrast agents:

Answer 43

When exposed to beams of adequate strength contrast harmonics are created because of nonlinear changes in bubble size.

Question 44

The amount of contrast harmonics produced may be estimated by a number called?

Answer 44

Mechanical index

Question 45

The strength of a tissue harmonic wave grows as the transmitted sound travels deeper into the tissue?

Answer 45

True