Chap 3 Level 2

Question 1

What is echogenicity

Answer 1

Refers to the strength or type of signal reflection

Question 2

What is anechoic

Answer 2

• No echogenecity (no reflected signal)
• fluids, blood, bile, serous

Question 3

What is hypoechoic

Answer 3

• low echogenecity (low level reflected signals)
• fatty plaque, some masses

Question 4

What is hyperechoic

Answer 4

-high echogenecity (moderate to high reflected signals)

Question 5

What does Calcified mean in echo

Answer 5

• strongly echogenic
• usually has acoustic shadowing
• normally moving parts

Question 6

What is complex echoic

Answer 6

• mixed echogenecity (some bright, some dark)

Question 7

What are the 2 terms
That describe how uniform the signal appears

Answer 7

• homogenous implies signal is uniform
• heterogenous implies there’s variation in the image w/in the signal

Question 8

Plaque surface characteristics for smooth

Answer 8

• a continuous smooth surface that tends to be less symptomatic

Question 9

Plaque surface characteristics for irregular

Answer 9

Discontinuous surface structure that tends to be more symptomatic and like to embolize

Question 10

Soft tissue attenuation rate w/ formula

Answer 10

(0.5 dB/cm-MHZ)*(cm)(mhz)

Question 11

When frequency and depth increase, what else increases

Answer 11

Attenuation

Question 12

When does scattering occur

Answer 12

Scattering occurs when tissue is rough in respect to the wavelength

Question 13

What happens when waves go from a constructive interference to a destructive interference

Answer 13

Creates a finer speckle pattern

Question 14

What are two types of speckle patterns and their characteristics

Answer 14

• coarse speckle patterns: rough looking texture (larger black spaces)
• fine speckle pattern: smooth looking texture (smaller black spaces)

Question 15

%reflected and %transmitted equation

Answer 15

%reflected = (z2-z1/z2+z1)^2
%transmitted = 1 - (Z2-Z1/Z2+Z1)^2

Question 16

What does attenuation represent?

Answer 16

Transfer of energy through absorption and scattering

Question 17

What is absorption in the context of attenuation?

Answer 17

Conversion of wave energy into heat

Question 18

What is the dominant form of attenuation in soft tissue?

Answer 18

Absorption

Question 19

How does attenuation through absorption change with frequency?

Answer 19

Increases exponentially with higher operating frequencies

Question 20

What factors determine the amount of energy reflected?

Answer 20

Acoustic impedance mismatch, incident angle, type of reflection

Question 21

What are the three categorizations of reflection?

Answer 21

• Specular reflection
• Scattering
• Rayleigh scattering

Question 22

What determines specular reflection?

Answer 22

Smoothness and size of the reflector relative to the wavelength

Question 23

Is specular reflection angle dependent?

Answer 23

Yes, it is highly angle dependent

Question 24

What causes scattering?

Answer 24

Occurs from surfaces that are rough relative to the wavelength

Question 25

What is Rayleigh scattering?

Answer 25

Occurs when reflectors are small relative to the wavelength (RBC)

Question 26

What is the formula for acoustic impedance?

Answer 26

Z = Density x propagation velocity