Chapter 17

Question 1

____ ____ is the creation of an image from sound reflections at twice the frequency of the transmitted sound.

Answer 1

Harmonic imaging

Question 2

____ ____ is the transmitted frequency.

Answer 2

Fundamental frequency

Question 3

____ ____ is twice the transmitted frequency.

Answer 3

Harmonic frequency

Question 4

What type of behavior means proportional or symmetrical - systems respond in an even manner.

Answer 4

Linear behavior

Question 5

What type of behavior means irregular or disproportionate - systems respond in an uneven manner

Answer 5

Non-linear behavior

Question 6

Harmonic frequency sound waves arise from ____ behavior.

Answer 6

Non-linear

Question 7

Harmonic imaging can produce a more accurate image because harmonic frequency waves undergo less ____ than fundamental sound waves.

Answer 7

Distortion

Question 8

As a sound wave travels in the body, a small amount of energy is converted from the ____ frequency to the ____ frequency.

Answer 8

Fundamental; Harmonic

Question 9

Tissue harmonics to be created during ____.

Answer 9

Transmission

Question 10

A sound wave is a series of ____ and ____.

Answer 10

Compressions and rarefactions

Question 11

Sound travels faster through ____ and slower through ____.

Answer 11

Compressions; Rarefactions

Question 12

During ____ ____, (no harmonics) significant amounts of artifact arise within the first few centimeters of tissue

Answer 12

Fundamental imaging

Question 13

During ____ ____ imaging NO harmonic signals are generated at extremely superficial depths.

Answer 13

Tissue harmonic

Question 14

As sound travels ____ in tissue, the strength of the harmonic wave becomes larger.

Answer 14

Deeper

Question 15

____ sound beams do not create tissue harmonic.

Answer 15

Weak

Question 16

____ strength sound beams create a tiny amount of tissue harmonics.

Answer 16

Intermediate

Question 17

____ sound beams create significant tissue harmonics.

Answer 17

Strong

Question 18

Side lobes and grating lobes are usually ____ so little or no harmonics are created in them.

Answer 18

Weak

Question 19

____ ____ ____ use the distortion free harmonic reflections, while eliminating the distorted fundamental reflections.

Answer 19

Pulse inversion harmonics

Question 20

Pulse inversion Harmonics is a more successful method of separating ____ and ____ frequencies.

Answer 20

Fundamental and harmonic

Question 21

How does pulse inversion harmonics work?

Answer 21

Two pulses are transmitted down a scan line

• 1st pulse is a typical pulse
• 2nd pulse is an inverted copy (it’s opposite)

Where a compression occurs in the 1st pulse, a rarefaction occurs in the 2nd

Upon arriving back to the receiver, these pulses are combined.

Question 22

____ ____ (microbubbles) are gas bubbles encased in a shell that are injected into the circulation (I.V. typically) or swallowed.

Answer 22

Contrast agents

Question 23

Contrast agents must meet five requirements:

Answer 23

1. Safe
2. Metabolically inert –it won’t change in a biological system
3. Long lasting
4. Strong reflector of ultrasound
5. Small enough to pass through capillaries

Question 24

Constrast harmonics are created during ____.

Answer 24

Reflection

Question 25

This expanding and shrinking when a microbubble is in a sound beam is called ____.

Answer 25

Resonance

Question 26

What is the most important formation of contrast harmonics?

Answer 26

Rarefaction

Question 27

When a microbubble is exposed to the high pressure component of a sound wave, the microbubble ____.

Answer 27

Shrinks

Question 28

When a microbubble is exposed to the low pressure component of a sound wave, the microbubble ____.

Answer 28

Expands

Question 29

____ ____ is a number that estimates the amount of contrast harmonics produced.

Answer 29

Mechanical index (MI)

Question 30

The mechanical index increases with:

Answer 30

1. Lower frequency sound
2. Stronger sound waves

Question 31

Microbubbles the size of red blood cells just so happen to resonate in the ____MHz – ____MHz range

Answer 31

2 MHz – 4 MHz

Question 32

Two characteristics of contrast agents that are important are the ____ ____ and the ____.

Answer 32

Outer shell; Gas

Question 33

The shell needs to be ____ so the microbubbles can change shape.

Answer 33

Flexible

Question 34

The gas needs to be made of ____ molecules so that it remains trapped within the bubble, no leaking out!

Answer 34

Large