Study guide Ch 16/17:quiz 1

Question 1

What are the five requirements for contrast agents?

Answer 1

Contrast agents must be:

1) safe
2) metabolically inert (metabolized throughout system and then removed)
3) long lasting
4) strong reflector of ultrasound
5) small enough to pass through capillaries

Question 2

If you know the fundamental frequency of a transducer, what is the harmonic frequency?

Answer 2

harmonic frequency is twice the fundamental frequency

Question 3

If you are in harmonic mode, what is the fundamental frequency?

Answer 3

fundamental frequency is 1/2 the harmonic mode

Question 4

What type of behaior creates harmonics?

Answer 4

nonlinear behavior

Question 5

Fewer shades of gray

Answer 5

few choices

black and white(bistable)

narrow dynamic range

high contrast

Question 6

many shades of gray

Answer 6

many choices

gray scale

wide dynamic range

low contrast

Question 7

Tissue harmonics

Answer 7

created during transmission in tissue

occurs as sound propagates in tissue

results from nonlinear behavior of transmitted sound beam

weaker harmonic signal

Question 8

Contrast harmonics

Answer 8

created during reflection off of microbubble

occurs only when contrast agents are present and with MIs > 0.1

results from nonlinear behavior of microbubble

stronger harmonic signal

Question 9

How is Mechanical Index calculated?

Answer 9

MI= peak rarefaction pressure/ square root of frequency

Question 10

Mechanical Index and Harmonics

Low MI:<0.1

Answer 10

No harmonics

backscatter

linear behavior

higher frequency sound

low beam strength

bubble expands very little

Question 11

Mechanical Index and Harmonics

Higher MI 0.1-1.0

Answer 11

some harmonics

resonance

nonlinear behavior

lower frequency sound

higher beam strength

bubble expands moderately

Question 12

Mechanical Index and Harmonics

Highest MI: >1

Answer 12

strongest harmonics

bubble disruption

extreme nonlinear behavior

lowest beam strength

bubble expands greatly

Question 13

What is pulse inversion?

Answer 13

Pulse inversion utilizes harmonic reflections while eliminating distorted fundamental reflections

Pulse inversion harmonics:

utilizes a wide range of frequencies, positive and negative reflections are combined

Disadvantages:

time required to create a frame is doubled, frame rate is halved, temporal resolution is reduced