Physics 17

Front 1

What are two significant advancements In diagnostic Ultrasound

Back 1

Harmonic imaging and contrast agents

Front 2

What is harmonic imaging

Back 2

It is the creation of an image from sound reflections at twice the frequency of the transmitted Sound

Front 3

Fundamental frequency

Back 3

The frequency of sound created by the transducer and transmitted into the body

Front 4

Harmonic frequency is also known as

Back 4

Second harmonic frequency

Front 5

Harmonic frequency is

Back 5

Twice the fundamental frequency

Front 6

Harmonic frequency sound waves aRise from

Back 6

Nonlinear behavior

Front 7

What is a fundamental image

Back 7

The image created by processing reflections that have the same frequency as the transmittedSound

Front 8

What is a harmonic image

Back 8

The image created by processing reflections that are twice the fundamental frequency

Front 9

Harmonic imaging is most useful in

Back 9

Improving poor quality images because harmonic frequency waves undergo list distortion then fundamental sound waves

Front 10

Two forms of harmonics are important in diagnostic sonography

Back 10

Tissue harmonics and contrast harmonics

Front 11

Linear means

Back 11

Proportional or symmetrical

Front 12

Linear systems respond In a

Back 12

Even manner and in a symmetrical manner

Front 13

Nonlinear behavior

Back 13

Non linear means irregular or diss proportionate

Front 14

Non-linear behavior is

Back 14

Asymmetrical

Front 15

Harmonic frequency sound arises from

Back 15

Non-linear behavior

Front 16

As a sound wave travels in the body, a minuscule amount of energy is converted from the fundamental frequency to the harmonic frequency disc conversion create

Back 16

Tissue harmonics

Front 17

A sound wave is a series of

Back 17

Compressions and rare fractions

Front 18

Sound travels faster through?

Sound travel slower through?

Back 18

Compressions

Rare factions

Front 19

During fundamental imaging, significant amounts of artifact arise with the first few centimeters of tissue. The strong artifacts appear for two reasons?

Back 19

The beam is very strong

The many different superficial and atomic layers distort the sun beam

Front 20

Tissue harmonic signals do not exist at

Back 20

Extremely superficial depths, they develop deeper in the tissue

Front 21

Because they do not exist in superficial Depths,Harmonic signals cannot

Back 21

Distort

Front 22

Do use of harmonics increases

Back 22

Signal to noise ratio

Front 23

With tissue harmonics, the relationship between the sound beam strength and harmonic creation is

Back 23

Also non-linear

Front 24

When sound beams are distorted, a small portion of the sound energy is

Back 24

Directed away from the beams main axis in the form of side lobes or grating lobes

Front 25

Beams that are most likely to create harmonics are

Back 25

Least likely to create artifacts

Front 26

Tissue harmonics are

Back 26

– Not present at soundwaves the transducer, they are created deeper in the tissues

– Created during transmission

– Created by Non-linear behavior

– Primarily created along the beams main axis

Front 27

PULSE inversion harmonics is

Back 27

An. Imaging technique specifically designed to utilize harmonic reflections, which are distortion free, what illuminating distorted fundamental reflections

Front 28

Reflections contain both

Back 28

Fundamental in harmonic frequencies

Front 29

Fundamental imaging create images from the portion of the reflected sound that has

Back 29

The same frequency as a transmitted sound

Front 30

Harmonic imaging creates

Back 30

Images only from the harmonic, which is twice the frequency of the transmitted Sound

Front 31

Pulse Inversion harmonics separate

Back 31

The harmonics from the fundamental frequency is more successfully

Front 32

With pulse inversion harmonics, Two consecutive ultrasound pulses are transmitted down each scanline the first is?The second is?

Back 32

A typical pulse

The second is an inverted copy that is out of phase with the first

Front 33

Where ever a compression exist in the first pulse?

Back 33

A rare faction exist in the second

Front 34

Since fundamental portions of the reflections exhibit linear behavior, the two inverse fundamental signals?

Back 34

Cancel each other out

Front 35

Since harmonics exhibit and non-linear behavior, the harmonic portions are the reflections are

Back 35

In phase and interfere constructively

Front 36

The disadvantage of Pulse Inversion harmonics is the

Back 36

To pulses Are transmitted down each scanline and twice the number of pulses are required to create each image

Front 37

The time required to create a frame

Back 37

Is doubled, the frame rate is have, and temporal resolution is reduced

Front 38

Power Doppler modulation is another imaging technique specifically designed to

Back 38

Augment harmonic reflections, which contain less distortion, while eliminating distorted fundamental reflections

Front 39

Contrast harmonics are created because

Back 39

Micro bubbles act in a nonlinear manner when struck by sound waves

Front 40

Contrast harmonics are created during

Back 40

Reflection, as energy is converted from the fundamental frequency to the harmonic frequency

Front 41

When a microbubble is with in a sound beam, the bubble?

Back 41

Grows And shrinks in relation to this pressure variations

Front 42

When exposed to sound beams of adequate strength, contrast harmonics are

Back 42

Created because of the nonlinear changes in bubble size

This uneven behavior is called resonance

Test question

Front 43

When exposed to the high-pressure component of a soundwave the bubble

(Compression)

Back 43

Shrinks and the pressure inside the bubble increases

Front 44

The bubble stabilizes, resisting further compression,

Back 44

which limits how small the bubble will become

Front 45

When exposed to the low-pressure component of a sound Been(rarefactions)

Back 45

The bubble expands

Front 46

Bubbles expand

Back 46

To a greater extent than they shrink

Front 47

Peak rare faction pressure, which expands the bubble, is

Back 47

Most important with regard to contrast harmonics

Front 48

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

Back 48

A number called the mechanical index

Front 49

Power modulation harmonics achieves the same goals as pulse in version but

Back 49

Uses different engineering approach

Front 50

The mechanical index depends on

Back 50

The frequency of the transmitted sound in the rear friction pressure of the soundwave

Front 51

The numerical value of the mechanical index, and therefore, harmonic production, increases with

Back 51

–Lower frequency sound, and

– Stronger sound waves (substantial pressure variation)

Front 52

Mechanical index =

Front 53

Micro bubbles the size of red blood cells resonate when exposed to sound in the

Back 53

2 to 4 MHz range

Front 54

Is there another form of nonlinear behavior of a microbubble that create contrast harmonics

Back 54

Yes, a second form of nine lean your behavior occurs with contrast agents

Front 55

Low mechanical index sound beams do not

Back 55

Create harmonics because the microbubbles expand and contract evenly in a linear fashion

Front 56

When mechanical index is less than 0.1, Bubbles create

Back 56

Only backscatter – similar to other biologic reflectors

Front 57

Beams with an intermediate mechanical index, 0.1 to 1.0, create?

Back 57

A relatively small amount of harmonics

Front 58

Beams with a Hi mechanical index (greater than 1.0) create

Back 58

Substantial harmonic signals

Front 59

Bubble disruption is an example of

Back 59

Nonlinear behavior, which creates a very strong harmonic reflections

Front 60

Mechanical index =

Back 60

Front 61

Two characteristics of contrast Agents are important

Back 61

-The nature of the outershell

– The gas that fills the microbubble

Front 62

The relationship between the shell and internally trapped gas determines the contrast agent stability and it’s long Jevity was circulating in blood

Back 62

–shells trap the gas and increase the life

– Shells are designed to be flexible so they can change shape

– The gas trapped in the interior of the shell determines the stability

Front 63

Since harmonics Exhibit non linear behavior the week or first reflection does not? The stronger second reflection contains?

Back 63

Does not contain harmonics

Contains harmonics

Front 64

During reception, The reflections from the first pulse are

Back 64

Doubled and then subtracted from the second reflection

Front 65

Since to pulses are transmitted don’t eat scanline, the frame rate is

Back 65

Halved, and the temporal resolution is reduced

Front 66

Country estate gents also called

Back 66

Micro bubbles, are gas bubbles encapsulated in a shell

Front 67

How do you use contrast agents

Back 67

They can be injected intravenously or ingested

Front 68

Contrast agents are designed to

Back 68

Create strong reflections that actually light up blood chambers, vessels, or other anatomical regions

Front 69

Contrast agents must meet the following five requirements

Test question

Back 69

-Safe

-Metabolically inert

-Long lasting

-Strong reflector of ultrasound

-Small enough to pass through capillaries

Front 70

How do the Strength of tissue and contrast harmonics compare?

Back 70

Contrast harmonics created by microbubbles are much stronger then tissue harmonics

Front 71

Contrast harmonics are

Back 71

– Created during reflection

– Created by nonlinear behavior

– related to the mechanical index

– Affected by the microbubbles shell and the gas within