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Ultrasound Physiscs > Final Flag Questions > Flashcards

Final Flag Questions Flashcards

1
Q

what does affect power Doppler signal?

A

the density/concentration of RBCs determines the amplitude

more RBCs = increased amplitude = brighter the image

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2
Q

what does FFT do?

A

a mathematical process to display various velocities of RBCs traveling through vessels as a graph of velocities over time.

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3
Q

what is wrong with this image?

A

improper color box steering

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4
Q

Doppler Artifacts

Mirror image occurs with spectral and color Doppler and can be caused by _______ or _______

A

too-high Doppler gain

angle too close to 90 degree

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5
Q

Doppler Artifacts

what kind of artifact is this?

A

color bruit

a stenosis, AV fistula, or pseudoaneurysm can cause a “thrill” or tissue vibration due to high velocity - this tissue motion is picked up by color Doppler

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6
Q

Fix this image

A

3: increase scale

*notice: aliasing

when you see aliasing, increase the scale!

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7
Q

what type of artifact is this?

A

reverberation

appears as multiple, equally spaced reflections on an image
caused by sound bouncing back and forth between two strong reflectors and then returning to the TDR
comet-tail & ring-down artifacts are the forms of reverberation artifacts

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8
Q

What type of artifact is this?

A

comet tail

called “twinkle artifact” in color

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9
Q

what type of artifact is this?

A

ring-down

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10
Q

What type of artifact is this?

A

refraction artifact/ghost image

*image above: refraction from rectus muscles cause duplication of aorta

*image below: the aorta on the right is ghost image

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11
Q

Grating lobes can be reduced by…..

A

subdicing: slicing an element into small sub-elements, wired so they act together as a single element apodization: elements receive different voltages when excited (higher voltage in the middle, lower voltage at outermost element) tissue harmonics:

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12
Q

what type of artifact is this?

A

slice thickness/section-thickness artifact

*note: the image below is the transverse plane of the same image above. notice that echo within the vessel is gone, which means the echoes in the image above is artifact caused by the elevation

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13
Q

what type of artifact is this?

A

enhancement

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14
Q

what type of artifact is this?

A

focal banding

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15
Q

what type of artifact is this?

A

electronic noise

*there’s nothing you can do about it

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16
Q

what type of artifact is this?

A

speckle

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17
Q

what type of artifact is this?

A

comet tail

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18
Q

what type of artifact is this?

A

multiartifact

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19
Q

what type of artifact is this?

A

refraction/ghost image artifact

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20
Q

what type of artifact is this?

A

reverberation artifact

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21
Q

what type of artifact is this?

A

mirror image

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22
Q

what type of artifact is this?

A

reverberation

*apparent pedunculated mass in the apex of the ventricle caused by reverberation artifact

*if there’s motion with reverberation artifact, the motion of the artifact will be in the same direction as the motion of the actual structure

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23
Q

what type of artifact is this?

A

clutter artifact

*in PSAX view of the PV and PA

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24
Q

what type of artifact is this?

A

ring down artifact

*caused by air in the biliary system

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25
Q

what type of artifact is this?

A

ring down artifact caused by air at the boundary of the diaphragm and lung

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26
Q

what type of artifact is this?

A

TEE image of comet tail artifact (asterisks) created by the two discs from a bileaflet St Jude mechanical prosthetic MV

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27
Q

what type of artifact is this?

A

reverberation (comet tail) artifact emanating from the catheter

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28
Q

what type of artifact is this?

A

spurious second aortic valve root caused by grating lobe artifact

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29
Q

what type of artifact is this?

A

speed error artifact

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30
Q

what type of artifact is this?

A

mirror of a calcification in liver from the diaphragm

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31
Q

what type of artifact is this?

A

mirror artifact (arrow) of the IVC across the diaphragm

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32
Q

what type of artifact is this?

A

large mirror artifact reflected across the trachea

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33
Q

what type of artifact is this?

A

mirror artifact with lines indicating u/s path which creates the mirror of the anterior MV leaflet

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34
Q

what type of artifact is this?

A

gallbladder with acoustic shadowing from a gallstone

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35
Q

what type of artifact is this?

A

mage of the liver and right kidney with acoustic shadowing caused by the ribs

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36
Q

what type of artifact is this?

A

shadowing and enhancement of the femoral artery

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37
Q

Doppler Waveform Classification

A

reduced biphaisc

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38
Q

Doppler Waveform Classification

A

triphasic

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39
Q

Venous pressure and flow are affected by:

A
  • calf muscle pump
  • venous valve
  • respiration
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40
Q

The term applied when only the information from the selected gate will be processed is:

A

range resolution

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41
Q

Noise in the Doppler signal that is generally caused by high amplitude, Doppler shifted echoes is called:

A

clutter

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42
Q

Signal processing of the Doppler signal is accomplished by the:

A

Fast Fourier Transform

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43
Q

The attribute of colors that permits classification into a color is termed:

A

hue

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44
Q

the artifact that interferes with the ability to detect a low-contrast object is known as:

A

acoustic speckle

*acoustic speckle often considered to be an artifact because one-to-one correspondence between image brightness and scanned objects does not exist

45
Q

acoustic energy emitted in a direction different than from the main axis of the sound beam is called:

A

side lobes

46
Q

Harmonics can be used to eliminate:

A

reverberation

47
Q

when the Doppler gain is too high, which one of the following artifacts can appear on the image?

  1. aliasing
  2. cross talk
  3. comet tail
  4. shadowing
A

cross talk

*mirror image or crosstalk: spectral Doppler shows waveform above and below the baseline. It occurs when the Doppler gain is set to high or the Doppler angle is close to 90 degree

48
Q

What will improve acoustic speckle

A

Use of frame rate
Use of compound imaging

49
Q

If you want to improve boarder definition, what imaging enhancement should you use

A

Spatial compound imaging

50
Q

What can you do to improve visualization of distal acoustic shadowing from calcification

A

tissue harmonic imaging

51
Q

What artifact is the result of reverberation

A

comet tail

52
Q

When you select harmonic imaging which artifact is less likely to be observed

A

grating lobe

53
Q

When you select compound imaging, which artifact is less likely to be observed

A

Refraction
Shadowing
Enhancement
Acoustic speckle

54
Q

Science of identifying and measuring sound beam potential for biological effects

A

Dosimetry

*parameter: intensity, pressure, power

55
Q

unit for pressure

A

Pascal

*force per unit area

56
Q

unit for intensity

A

W/cm2 or mW/cm2

*power per unit area

57
Q

Acoustic Exposure is determined by:

A
  • sound beam intensity
  • exposure time
58
Q

Current FDA regulatory limit SPTA =

A

720 mW/cm2

*SPTA: The Spatial Peak Temporal Average (SPTA) is the average intensity over a time and area

*SPTA: most common measurement for u/s bioeffects

59
Q

What are the mechanical effects?

examples of MI

A

Radiation forces

streaming

acoustic cavitation

60
Q

What is mechanical index (MI)?

A
  • Used to describe output in terms of possible cavitation
  • Relates to likelihood of harmful bioeffects from cavitation
61
Q

If MI is > 1

A

risk of cavitation must be weighed against benefits of exam

*Related to Temporal Peak; thus, longer exposure time at high intensities will produce mechanical index > 1 and possible cavitation

*If MI is < 1 = low risk

62
Q

Intensities ______ mW/cm2 will induce cavitation.

63
Q

AIUM accepted SPTA intensities range from ____mW/cm2 depending on application (grayscale, color Doppler, M-mode, pulsed Doppler)

64
Q

________ frequencies increase risk of cavitation

65
Q

To minimize non-thermal bioeffects…

A

Decrease output power

Decrease dwell time

66
Q

No adverse non-thermal bioeffects have been reported below ______ (MI) in tissues with existing gas bodies & contrast

A

0.4 MPa (≈ MI < 0.4)

67
Q

In tissues without existing gas bodies, no adverse non-thermal bioeffects have been reported with MI _____

68
Q

MI is proportional to _____ and related to ______

A

peak rarefactional pressure

Temporal Peak (TP)

69
Q

FDA max MI =

70
Q

Thermal index should be kept at what number?

A

Less than 1.0 during all examination

71
Q

What is TI?

A

Thermal Index

•Used to describe ratio between output power and the amount of power it takes to raise tissue temperature by 1o C.

72
Q

No confirmed bioeffects under _____ SPTA (unfocused beam)

A

100 mW/cm2

73
Q

Doppler at high power levels has been shown to cause bioeffects

T or F ?

74
Q

HID equation

75
Q

BUR

A

Beam uniformity ratio (How uniform is the beam?)

  • Also called SP/SA factor
  • BUR = SP/SA
76
Q

There are Six different intensities are used to describe the sound beam:

• SATA

• SPTA

• SAPA

• SPPA

• SATP

• SPTP

Which one of them is the most relevant with thermal bioeffect?

A

SPTA

*SP: spatial peak

*TA: temporal average (measures 100% of time)

77
Q

Which of the following intensity measurement is made during the PRP?

  1. SPPA
  2. SPTP
  3. SATP
  4. SPTA
78
Q

What is defined as the action of an acoustic field within a fluid to generate bubbles?

A

cavitation

79
Q

sensitivity equation & its definition

A

The ability of a test to detect disease

(How many times the test correctly said there was disease divided by the total number of times there was disease.)

80
Q

specificity equation & its definition

A

The ability of a test to detect the absence of disease

(How many times the test correctly said there was no disease divided by the total number of times there was no disease.)

81
Q

Accuracy equation & its definition

A

The percentage of times the test is correct.

82
Q

________ probes have smaller dead zones

A

Higher frequency

83
Q

If I wanted to evaluate the contrast resolution of a transducer or US system, I would buy a:

  1. Doppler phantom
  2. AIUM 100mm phantom
  3. Tissue equivalent phantom
  4. Beam profile phantom
A

3.

The tissue equivalent phantom has taken cysts/masses in it and useful for evaluating contrast resolution

84
Q

The middle rod group of the AIUM phantom scanned from the top measures the:

  1. axial resolution
  2. depth calibration accuracy
  3. lateral resolution
  4. sensitivity
85
Q

vertical and horizontal accuracy of the electronic calipers. calibration accuracy is performed by scanning the vertical and horizontal equidistant rods from the top.

A

range accuracy

86
Q

The testing device composed of a series of 0.75mm diameter stainless steel rods arranged in groups suspended in fluid is the:

  1. AIUM 100 mm test object
  2. string phantom
  3. tissue phantom
  4. Doppler tissue phantom
87
Q

Statistical analysis is used to:

  1. find out if the result of the phantom testing is accurate
  2. find out if the results of the test object is accurate
  3. find out if the results of their clinical testing is accurate
  4. find out if the results of their academic testing is accurate
88
Q

The following information is needed to find the positive predictive value:

  1. all of the positive
  2. all of the negatives
  3. both the positives and negatives
  4. only the true positives and true negatives
A

1

*Negative/Positive Predictive value: prevalence of disease

PPV (Positive Predictive Value) - measures how often the test is correct when positive for disease (only includes the positive parameters)

PPV = TP/(TP+FP)

89
Q

_______ measures the percentage of examinations that correlated or matched with the gold standard

A

accuracy

*Accuracy = (TP)+(TN)/(TP)+(FN)+(TN)+(FP)

*accuracy falls between the sensitivity and specificity values and PPV and NPV

90
Q

Which adjustment would result in a decrease in MI ?

A

increase TDR frequency

*higher frequency = higher amplitude = higher pressure = less risk of MI

91
Q

Briefly describe the relationship between frequency and MI

A

inverse relationship

*note: MI is the highest during rarefaction (the lowest pressure)

using higher frequency TDR increases TI and patient’s exposure due to attenuation

92
Q

What is HITU?

A

high intensity therapeutic ultrasound (HITU) has re-emerged as a minimally-invasive and non-ionizing therapeutic modality for the treatment of a variety of diseased tissues, including uterine fibroid, prostate, breast, and brain

93
Q

What sonography application has the lowest FDA approved SPTA values

A

Ophthalmic

94
Q

Which has the highest SPTA value

95
Q

Which intensity parameter is not applicable for continuous wave ultrasound

A

SPPA and SAPA

96
Q

Which intensity descriptor has the lowest numerical value for the characterization of a pulsed wave ultrasonic field

97
Q

In an ultrasound phantom, the targets typically used for measuring axial resolution are:

A: Multiple round fluid-filled structures
B: Multiple round Hyperechoic simulated lesions
C: Multiple equidistant rods
D: Closely spaced targets of varying distances
E: Long fluid-filled tubes

A

Closely spaced targets of varying distances

98
Q

What can you test with a doppler flow patttern

A

Range gate accuracy
Spectral doppler velocity accuracy
Color doppler penetration

99
Q

String objects are used to evaluate

A

Doppler accuracy

100
Q

Which of the following is not a clinical for elastography?

  1. atherosclerotic plaque
  2. dermatology
  3. transplant evaluation
  4. focal drug delivery
101
Q

Which of the following is NOT an advantage to using harmonics during imaging?

  1. decreases the amount of noise artifact
  2. improves lateral resolution
  3. improves axial resolution
  4. decreases the amount of grating lobes
A

3

Poor axial resolution but can be improved by pulse inversion

102
Q

By approximately how many decibels does a contrast agent increase the signal of blood?

  1. 10 dB
  2. 30 dB
  3. 5 dB
  4. 20 dB
103
Q

If the microbubbles in a contrast enhanced ultrasound burst during an exam, what effect is shown on the image display?

  1. Mid level grayscale representing blood flow
  2. Very bright echoes representing blood flow
  3. Grayscale tissue will display without blood flow
  4. Shadowing from increased reflectivity due to large acoustic impedance mismatch
104
Q

Which statement is true of grayscale elastography?

  1. cancers are usually soft and appear as white structures
  2. cancers are usually stiff and appear as dark structures
  3. cancers cannot be characterized using grayscale
  4. cancers usually have the same stiffness as surrounding tissue
105
Q

Which statement is true of the Schlieren Device used to test ultrasound equipment?

  1. It produces image artifacts
  2. visualize ultrasound beam as it interacts in a medium
  3. It detects rates of absorption
  4. It charts detected output power
106
Q

Which is not currently an approved clinical application for focused ultrasound?

  1. liver carcinoma
  2. fibroid tumors
  3. prostate cancer
  4. breast cancer
107
Q

A quality assurance device that is used to check for clusters of sound waves located outside the main ultrasound beam axis is a good description of which type of equipment?

A

Schlieren Device

108
Q

Dynamic Elastography

A
  • Vibration is applied by external vibrator
  • Several vibration waves are tracked as they travel in tissue
109
Q

Transient Elastography

A

Singe vibration is sent and tracked as it travels.

Ultrasound Physiscs (18 decks)

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