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apex review > Ultrasound > Flashcards

Ultrasound Flashcards

1
Q

How fast does ultrasound propagate through soft tissue?
a. 343 m/sec
b. 1,540 m/sec
c. 3,051 m/sec
d. 4,892 m/sec

A

B. 1,540 m/sec

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2
Q

_____ forms the peak of the sound wave.

A

Compression (a region of high pressure)

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3
Q

______ forms the trough of the sound wave.

A

rarefaction (a region of low pressure)

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4
Q

A sound is simply a ______ that travels in a longitudinal wave.

A

pressure wave ( a form of mechanical energy)

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5
Q

Frequency is a measure of _______

A

pitch.

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6
Q

Frequency tells us how many

A

cycles occur in a given period of time

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7
Q

________ is the distance between two identical points on adjacent cycles.

A

Wavelength

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8
Q

______ frequencies produce shorter wavelengths, and _____ frequencies produce longer wavelengths

A

higher; lower

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9
Q

______ represents the sound’s loudness

A

Amplitude

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10
Q

Sound propagates through _____ at 343 m/sec and ____ at 3,000-5,000 m/sec

A

air; bone

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11
Q

Frequency is expressed in

A

hertz or cycles per second

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12
Q

When no medium is present (such as in a vacuum or outer space), there can

A

be no sound

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13
Q

Which concept BEST explains why lead zirconate titanate is commonly used in ultrasound transducers?
a. echolocation
b. doppler effect
c. Snell’s law
d. Piezoelectric effect

A

D. Piezoelectric effect

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14
Q

What is echolocation?

A

the use of sound and echoes to determine where objects are located in space.

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15
Q

A piezoelectric material can transduce

A

electric energy to mechanical energy and vice versa

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16
Q

The piezoelectrical material used by modern ultrasound transducers is called

A

lead zirconate titanate

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17
Q

What is the primary determinant of the vertical placement of each illuminated pixel on the ultrasound monitor?
a. time delay
b. resolution
c. acoustic impedance
d. doppler effect

A

A. time delay
the vertical placement of each dot is determined by how long it takes for the echo to return to the transducer (time delay)

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18
Q

The horizontal placement of each dot is determined by

A

the particular crystal that receives the returning echo

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19
Q

The vertical placement of each dot is determined by

A

how long it takes for the echo to return to the transducer (time delay)

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20
Q

The ultrasound transducer emits ultrasound waves into the body at a fixed rate, and then it listens

A

for echoes between each pulse- a process that repeats many times each second

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21
Q

______ produces high amplitude echos

A

Hyperechoic

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22
Q

_______ appear as dark shades of grey

A

hypoechoic

23
Q

________does not produce echos

A

Anechoic

24
Q

The brightness of each dot is determined by the

A

amplitude of the returning signal

25
Q

______ describes a tissue’s ability to transmit or reflect sound waves in the context of the surrounding tissues

A

Echogenicity

26
Q

______ structures appear bright

A

Hyperechoic
examples- bone

27
Q

____ produce weak (low amplitude) echoes

A

Hypoechoic
examples include solid organs, liver, skin, adipose, cartilage

28
Q

_____ appear black

A

anechoic

29
Q

Vascular structures appear as

A

black circles in short-axis and black tubes in long-axis

30
Q

______ pulsate, ______ do not

A

arteries; veins

31
Q

Peripheral nerves near the neuraxis tend to appear _________, but distal peripheral nerves are _______

A

anechoic; hyperechoic (white) with a characteristic honeycomb appearance

32
Q

Which process describes a sound wave that bounces off a tissue boundary that has a different acoustic impedance?
a. absorption
b. reflection
c. scatter
d. refraction

A

b. reflection

33
Q

______ is the process where a sound wave bounces off a tissue boundary of differing acoustic impedance

A

reflection

34
Q

_________ occurs as the ultrasound waves are lost to the body as heat

A

absorption

35
Q

______ occurs when the ultrasound wave encounters an object smaller than the wave

A

scatter

36
Q

________ is the bending of ultrasound wave that encounters a tissue boundary at an oblique angle

A

refraction

37
Q

Resolution is the ability to see

A

two separate things as two separate things

38
Q

The three types of resolution are

A

axial, lateral, and elevational

39
Q

Ultrasound waves leaving the transducer tend to

A

converge before diverging beyond a certain point
they don’t travel in a straight line

40
Q

The _____ is the region where the beam is the narrowest

A

focal zone

41
Q

The region between the transducer and the focal zone is called the ______

A

near zone (Fresnel zone)

42
Q

The region beyond the focal zone is called the

A

far zone (Fraunhofer zone)

43
Q

Examples of attenuation include

A

absorption, reflection, scatter, and refraction

44
Q

A _____ view looks at a structure in cross-section, while a _____ view looks at a structure along its length.

A

short-axis; long-axis

45
Q

As a sound wave propagates through the body, its strength naturally_____ and some of the sound waves never return to the transducer. These factors conspire to

A

decreases; reduce image quality through a process called attenuation

46
Q

Lower frequency transducers allows us to see_____________

A

Deeper inside the body but we sacrifice image resolution

47
Q

The array configuration describes the

A

Arrangement of piezoelectric crystals inside the ultrasound transducer

48
Q

The linear array transducer has a flat footprint that contains piezoelectric crystals arranged

A

In parallel

49
Q

The curvilinear array transducer has a convex footprint with the arrangement of piezoelectric crystals inside

A

Following suit

50
Q

A ____________ is very narrow in the near field and fans out with increasing depth

A

Phased array transducer

51
Q

Describe the frequency range, imaging depth, & application examples for a high frequency array US transducer

A

> 10 MHz, <3 cm below skin,
Interscalene, supraclavicular, axillary, forearm, ankle, wrist, femoral, ankle, superficial blood vessels

52
Q

Describe the frequency range, imaging depth, & application examples for A medium frequency array transducer

A

5-10 MHz, 3-6 cm below skin,
Infraclavicular, sciatic, popliteal, deeper blood vessels

53
Q

Describe the frequency range, imaging depth, & application examples for a low frequency array transducer

A

> 6 cm below skin,

apex review (224 decks)

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