1
Q
What are the 3 types of ultrasound imaging?
A
A mode (measures distance between sound beam and receptor), B mode, M mode
2
Q
Which type of imaging provides range ambiguity?
A
Continuous wave; there’s no specificity due to the lack of a sample gate
3
Q
What do the X and Y axes signify in M mode?
A
X is time, Y is depth
4
Q
When color aliasing is present within a vessel with the appropriate settings, what flow is it likely representing?
A
Turbulent blood flow
5
Q
Describe the characteristics of a mechanical transducer (shape, # elements, steering, focus, image shape, damaged element consequences).
A
Shape: circular
Elements: 1 (small footprint)
Steering: physical rotation of the crystal
Focus: fixed depth
Image shape: fan/sector
Damaged element: entire image loss
6
Q
What are transducer arrays?
A
Arrangement of multiple crystals where each one is paired with its own wire; includes phased and sequential arrays
7
Q
What is the difference between phased vs sequential array transducers?
A
Phased = all crystals fire at the same time, top of image different shape than bottom
Sequential = one scan line present, top and bottom of the image are the same shape
8
Q
Describe the characteristics of a linear phased array transducer (shape, # elements, steering, focus, image shape, damaged element consequences).
A
Shape: rectangular
# elements: 100-300 (small footprint)
Steering: phasing, angling out like wheel spokes
Focus: electronic (adjustable by the sonographer)
Image shape: fan/sector Damaged element
Damaged element: erratic focusing
9
Q
Describe the characteristics of a annular phased array transducer (shape, # elements, steering, focus, image shape, damaged element consequences).
A
Shape: disc / bullseye / onion
# elements: multi-ringed elements
Steering: physical rotation of the crystal
Focus: multi-focus
Image shape: fan/sector
Damaged element: horizontal band of image loss
10
Q
Describe the characteristics of a linear sequential array transducer (shape, # elements, steering, focus, image shape, damaged element consequences).
A
Shape: rectangular
# elements: 120-250 (large footprint)
Steering: some elements fire simultaneously/parallel
Focus: electronic (time delays)
Image shape: rectangular
Damaged element: vertical line of image loss
11
Q
Describe the characteristics of a curvilinear sequential array transducer (shape, # elements, steering, focus, image shape, damaged element consequences).
A
Shape: rectangular
# elements: 120-250 (large footprint)
Steering: some fire at the same time, not in parallel due to curved face of probe
Focusing: electronic (time delays)
Image shape: blunted fan/sector
Damaged element: top to bottom straight line of information loss
12
Q
Describe the characteristics of a vector array transducer (shape, # elements, steering, focus, image shape, damaged element consequences).
A
Shape: rectangular
# elements: 120-250 (small footprint)
Steering: some elements fired simultaneously, but in different directions
Focus: electronic (time delays)
Image shape: trapezoid
Damaged element: top to bottom straight line of information loss
13
Q
What is elevational resolution?
A
Aka slice thickness; the ability to distinguish two points along a perpendicular plane to the sound beam
14
Q
What is a common artifact related to elevational resolution?
A
Slice thickness artifact aka side/grating lobes
15
Q
How can you reduce side/grating lobe artifact?
A
Apodization; focusing the strength of the signal towards the center and weakening the outer crystals strength
Subdicing; physical division of a crystal into a group of smaller crystals that work as a single unit
16
Q
What is frame rate determined by?
A
Speed of sound in a medium
Imaging depth
17
Q
When the machine puts in more work, the frame rate ______________. When the machine puts in less work, the frame rate _____________.
A
Decreases, increases
18
Q
How is frame rate related to temporal resolution?
A
Directly
19
Q
What is temporal resolution?
A
The ability of the machine to distinguish structures at the right time and place
20
Q
When frame rate increases, what happens to temporal resolution? How about when frame rate decreases?
A
Increases, decreases
21
Q
What are 2 sonographer controlled settings that determine frame rate?
A
Imaging depth
Number of pulses in each picture (sector size, focal zones, and line density)
22
Q
How are Tframe and frame rate related?
A
Reciprocals/inversely - Tframe x frame rate = 1
23
Q
Describe what happens when imaging depth is shallow.
A
Short go-return time, less time being taken to generate an image
Shorter t frame
Higher frame rate
Superior temporal resolution
24
Q
Describe what happens when imaging depth is deeper.
A
Longer go-return time
Long t frame
Lower frame rate
Inferior temporal resolution
25
How are imaging depth and t frame related?
Directly
26
What factors affect the number of pulses per image?
Sector size
Focal zones
Line density
27
Describe how single vs multiple focal zones affect the image.
Single: one pulse per scan line, short t frame, high frame rate, better temporal resolution, poor lateral resolution
Multi: many pulses per scan line, longer t frame, low frame rate, poor temporal resolution, better lateral resolution
28
How does narrow sector size affect the image?
Fewer pulses per frame, short t frame, high frame rate, superior temporal resolution
29
How does a wide sector size affect the image?
Many pulses per frame, longer t frame, lower frame rate, inferior temporal resolution
30
How does a low line density vs high line density affect an image?
Low: fewer pulses, short t frame, high frame rate, high temporal resolution, poor spatial resolution
High: more pulses, longer t frame, lower frame rate, low temporal resolution, high spatial resolution
31
What does spatial resolution depend on?
Axial resolution
Lateral resolution
Elevational resolution/slice thickness
32
How are depth and frame rate related?
Inversely
33
What are the two major functions of the machine?
Prepare and transmit a signal
Translate reception into something suitable for display and storage
34
What are the components of the machine that work together?
Master synchronizer
Pulser/beam former
Receiver
Digital memory
Display
Storage
35
What is the responsibility of the pulser?
Functions during transmission, altering the strength of the signal propagating into the patient
36
What does the pulser alter that affects the image?
The output power; less power = darker image, more power = brighter image
37
What kind of transducers does the beam former exist in?
Modern day arrays with multiple crystals
38
What is the normal voltage for a pulser to operate at?
0-500 volts
39
What ratio increases as we increase output power?
Signal to noise ratio
40
How are PRF and PRP a related to each other?
Reciprocals / inversely ; PRF = 1/PRP
41
When depth is increased, PRP ________ and PRF __________.
Increases, decreases
42
How does the beam former reduce side lobe artifacts?
Apodization
43
What are the order of receiver operations?
Amplification
Compensation
Compression
Demodulation (includes rectification and smoothing)
Reject
44
Describe the function of each receiver operation.
Amplification: making waves bigger by increasing overall gains
Compensation: making up for attenuation by adjusting TGCs
Compression: compresses signal into a range the machine can handle (I.e. zip file for storage) and into a version suitable for the human eye (controls the # of grey shades in the image)
Demodulation: rectification (converts negative voltages into positive ones above baseline) and smoothing (envelopes pulses)
Reject: getting rid of low level / unimportant information
45
What are 2 other ways to refer to TGCs?
Depth Gain Compensation (DGCs) or swept gain
46
At which point does the signal attenuate the most in reference to TGCs?
The knee of our TGCs (third ish to last slider)
47
What are 2 other names for compression?
Log compression and dynamic range
48
What is the difference between output power vs overall gains?
Output power affects ALARA and is only functional during transmission, while overall gains are adjustable after the image is taken and does not impact ALARA
49
Describe the difference between a bi-stable vs gray scale imaging.
Bi-stable: only black or white color
Gray scale: several shades of gray
50
When may bi-stable imaging be favored?
When imaging fluid filled structures, vessels, assessing for pleural effusion
51
Are bistable and gray scale imaging high or low contrast?
Bistable is high contrast, gray scale is low contrast
52
What is a scan converter?
Responsible for storing images while the scan is being created for viewing and record keeping, along with converting data to be viewed on the monitor as a live video
53
Describe the differences between analog scan converters vs digital scan converters.
Analog: monitors display information as raster lines, buffering this information as it converts into the other format
Digital: stores data as numbers/raw data that then needs to be converted back into an open exam
54
What are the cons of analog scan converters?
Inconsistent since image quality degrades after storage
55
What are 2 elements of scan converters?
1. Pixel density: # pixels per image
2. Bit: smallest amount of computer memory, valued at 0 or 1
56
What is a pixel?
The smallest portion of a digital image
57
When pixel density increases, what happens to the resolution?
Also increses
58
Define binary, byte, and word.
Binary - a group of bits, which presents as a series of 0s and 1s
Byte - group of 8 bits
Word - 2 bytes or 16 bits
59
How are the shades of gray displayed on an image related to bits?
2^n = # shades of gray displayed, where n = bits
60
What are analog scan converter images sensitive to?
Humidity and temperature
61
What kind of scan converters are modernly used?
Both analog and digital
62
What do A to D and D to A represent?
A to D is the analog signal input being processed for display/storage, while D to A is retrieving information stored for display
63
64
65
The scan converter has to write and read the information that it’s being fed. What are these called?
Preprocessing (write) and post processing (read)
66
What does preprocessing entail?
Adjusting settings prior to freezing the image along with write magnification (zooming in on an area of interest prior to capturing the image). This can also include adjusting color gains, scale, number of focal zones
67
What does post processing entail?
Adjusting the image after freezing along with read magnification (zooming in after freezing the image)
68
How does write and read magnification actually alter the image?
Write- smaller pixels, increase in pixel density and resolution since new data is actively being acquired
Read- enlarges pixels that are already thereand creates a coarse echo texture, no new data acquired
69
What is coded excitation?
Designed to shorten pulse length by distributing energy across a broad range of frequencies (wide bandwidth)
Basically shorter pulses with higher intensity
70
Where does coded excitation occur?
In the pulser
71
When frequency increases, what happens to the pulses?
They shorten
72
What does coded excitation use to output a short high amplitude pulse through pulse compression?
A modulated and long duration pulse
73
What is spatial compounding? Is it part of pre or post processing?
Averages multiple frames from different angles of insonation, improving visualization beneath highly attenuating structures
74
What does spatial compounding reduce?
Speckle and noise artifact
75
What is frequency compounding?
Multiple images that were taken with different frequencies are averaged into one image; there’s a large bandwidth of frequencies being reflect back towards the transducer
76
77
What does sub band frequencies refer to?
Frequency compounding (many frequencies are being sent into tissue space)
78
What does frequency compounding reduce?
Speckle and noise artifact
79
What is edge enhancement?
Post processing and digital technique that enhances pixels and their neighbors to reduce edge shadowing and speckle noise artifacts
80
What is temporal compounding?
Spatially averaging image frames to create an image
81
What does temporal compounding decrease?
Frame rate and temporal resolution
82
What is pixel interpolation?
Assigns a brightness value to missed pixels in an empty blind spot area, mimicking the pixels surrounding it
83
What is panoramic imaging?
Expands an image past the normal limits, building on data continuously
84
What is elastography?
Measures the stiffness of tissue, usually of the breast and liver
85
What is dynamic range?
The extent at which a signal can vary and still be processed
86
How is dynamic range expressed?
As a ratio between the largest and smallest signals in dB
87
Individual components of the ultrasound system have different dynamic ranges. What is the widest to narrowest of the system?
Transducer (120 dB)
Receiver (100-120dB)
Scan converter (40-50dB)
Display (20-30dB)
Archive (10-30dB)
88
Dynamic range _____________ as the data moves through processing.
Decreases
89
Describe a compressed vs uncompressed signal. How does it relate to dynamic range?
Compressed: signal is made smaller
Uncompressed: original signal
We can calculate the strength of the original signal or the compressed signal by adding / subtracting accordingly I.e if a signal is 70 db fate being compressed 40 db, the strength of the original signal is 110db
90
What are harmonics?
High frequency sound waves that are generated by the tissue due to nonlinear behavior by the fundamental frequency
91
Sound waves travel ___________ during compressions and ____________ during rarefactions.
Slower, faster
92
What does harmonics improve?
Axial and lateral resolution, reduces noise
93
What are the 2 ways harmonics can be utilized?
Tissue harmonic imaging
Contrast
94
What is fundamental frequency vs harmonic frequency?
Fundamental= original frequency
Harmonic= 2x the fundamental frequency returning back to the probe
95
In which field are the best tissue harmonic effects? Why?
Mid field; harmonics are not yet generated in near field, but in far field they attenuate faster than they are produced
96
What does tissue harmonic imaging decrease?
Temporal resolution and frame rate
97
What are contrast agents? How can contrast harmonics play a role in improving the image?
Microbubbles that are entrapped within a strongly reflective shell, either swallowed or administered via IV.
Harmonics are created during reflection off the microbubbles, NOT during transmission as seen with tissue harmonics
98
What are contrast harmonics determined by?
The shell and gas being used as the contrast agents
99
As mechanical index increases, what happens to harmonics?
Low MI - no harmonics
Mid - some harmonics
High- a lot of harmonics
100
Describe flow volume rate vs velocity.
Flow volume rate = Volume of blood moving at a particular time I.e Liters/min
Velocity = the speed at which flow is moving I.e cm/s
101
What are the forms of flow and their contributing factors?
Pulsatile - arterial, due to heart contractions
Phasic - venous, due to respiration
Steady - venous, only in MPV as normal flow / abnormal (nonocclusive DVT)
102
Where do we see laminar flow?
High flow and high pressure vessels I.e. aorta
103
How does blood flow travel through a stenosis?
Laminar flow before, stenosis will spike the velocity of blood flow, then flow becomes turbulent
104
What is necessary for fluid to flow from one place to another?
A pressure/energy gradient
105
What are the 3 forms of energy?
Potential (pressure) energy: not moving
Kinetic: determined mass and speed
Gravitational: also potential energy but at an elevated surface
106
What are the 3 factors of energy loss?
Viscosity
Friction
Inertia
107
Where there are high velocities, there is __________ pressure.
Low
108
What are the 3 characteristics of a stenosis?
Elevated velocities
Post stenotic
Spectral broadening
109
How is pressure gradient related to flow and resistance?
PG = FLOW X RESISTANCE
110
How does Ohm’s Law relate to look flow through the body?
They are both like circuits
Ohms law states voltage=resistance x current
Blood flow is pressure = resistance x flow
111
What is hydrostatic pressure?
The weight of a column of blood against the vessel wall upon standing
112
How does hydrostatic pressure increase with each foot below the heart?
By 22 mmhg
113
What is the hydrostatic pressure for a patient that is supine?
0
114
What would be the most accurate representation of true circulatory pressure?
Supine and at the level of the heart
115
What inspiration occurs….
Thoracic pressure decreases, abdominal pressure increases, upper extremity venous blood flow increases and lower extremity venous blood flow decreases
116
When expiration occurs…
Thoracic pressure increases, abdominal pressure decreases, upper extremity venous blood flow decreases, and lower extremity venous blood flow increases
117
Which of the following transducers creates a rectangular-shaped image?
Linear sequential
Linear phased
Curvilinear sequential
Annular
Linear sequential
118
Which of the following terms also describes sequential?
Switched
Phased
Array
Steered
Switched
119
Which of the following transducers creates a shape like the spokes of a wheel radiating from a single point? (2 answers)
Linear sequential
Linear phased
Curvilinear sequential
Annular phased
Linear and annular phased
120
Which of the following transducers creates a trapezoid image shape?
Curvilinear sequential
Vector array
Annular phased
Linear phased
Vector array
121
Which of the following transducers creates an image by permitting parallel lines that are the same size as the transducer face when lined up?
Linear phased array
Linear sequential array
Annular phased array
Vector array
Linear sequential array
122
Which of the following transducers electronically focus the sound beam?
Linear phased
Mechanical
Vector array
Curvilinear sequential array
Linear phased
Vector array
Curvilinear sequential array
123
Which of the following transducers creates a multiple transmit focal zones through the use of its unique phased technology?
Annular phased array
Curvilinear sequential array
Linear sequential array
Vector array
Annular phased array
124
A transducer with a combination of both linear sequential and linear phased is called?
Vector array
Annular array
Phased array
Curvilinear array
Vector array
125
Multiple disc shaped elements similar to rings of a bulls eye target is which one of the following transducers?
Linear phased array
Vector array
Curvilinear sequential array
Annular array
Linear sequential
Annular array
126
This transducer has a small footprint / small square where the beam is steered and focused electronically.
Annular phased
Linear phased
Convex array
Linear sequential
Linear phased
127
This transducer has a fan or sector shaped image and when it malfunctions, only a portion of the image is lost in a horizontal side to side band of dropout.
Linear phased
Vector array
Annular phased array
Convex array
Annular phased array
128
Linear switched array transducers are steered and focused by which of the following methods?
Mechanical
Electronic
Fixed
Lens and mirrors
Electronic
129
Describe a clinical situation where a sonographer may sacrifice temporal resolution in order to have better lateral resolution with multiple focal carats in place.
If they’re trying to detail a specific area of interest that is stationary, such as a mass or organ
130
What is the sonographically equivalent to the size of a painters canvas?
Sector size
131
A sonographer adjusts the depth from 5 to 10 cm. What happens to the frame rate?
It is halved
It doubles
It increases from 5 to 10 MHz
It is unchanged
It is halved
132
A sonographer adjusts the depth from 5 to 10 cm. If the frame rate remains the same, which one of the following also occurs?
Increased line density
Wider sector
Multi focus imaging turned on
Narrower sector
Narrower sector
133
A sonographer adjusts their sector size from 90 to 45 degrees. What happens to the frame rate?
It is doubled
It is halved
It is tripled
It remains unchanged
None of the above
It is doubled
134
Using a phased array transducer, a sonographer turns off the multi focus feature. What is the most likely consequence of this action?
Frame rate decreases
Temporal resolution decreases
Imaging depth increases
Temporal resolution improves
None of the above
Temporal resolution improves
135
A sonographer increases the line density from 1 to 3 in a given sector. What is the most likely consequence of this action?
Frame rate increases
Temporal resolution decreases
Imaging quality decreases
Temporal resolution increases
Temporal resolution decreases
136
How does the addition of color Doppler affect frame rate?
Increases FR
Decreases FR
Frame rate unaffected
Decreases FR
137
Thresholding or suppression are other terms that mean…
Compression
Compensation
Demodulation
Reject
Reject
138
A receiver function that converts negative voltages into positive voltages is called…
Demodulation
Reject
Compression
Amplification
Demodulation
139
A function of the receiver that places an envelope around the electrical bumps to even the signals out is called…
Amplification
Demodulation
Smoothing
Compression
Smoothing
140
This function is designed to prevent electrical noise from contaminating tiny meaningful signals…
Amplification
Compression
Preamplification
Reject
Thresholding
Preamplification
141
Which of the following is not a component of the ultrasound system?
Pulser
Alternator
Transducer
Synchronizer
Receiver
Display
Alternator
142
Increasing the strength of the signals before they enter the body is performed by which of the following?
Receiver
Compensation
Output power
Overall gain
Compression
Output pwoer
143
Which of the follows statements is/are correct?
When the signal to noise ratio is high, image quality decreases
When the signal to noise ratio is low, the image quality increases
When the signal to noise ratio is high, the image quality increases
When the signal to noise ratio is high, the image quality increases
144
Which of the following controls the pulse repetition period?
Receiver
Pulser
Overall gain
Master synchronizer
Pulser
145
Dynamic range is a synonym for….
Compression
146
The smallest building block of a digital picture is called…
Byte
Converter
Bit
EOH
Pixel
Pixel
147
A series of 0s and 1sis called a…
Decimal
Binary number
Bit
Byte
Binary number
148
How many bits are required to store 9 shades of gray?
1
2
4
6
4
149
Converting information from the patients body to the ultrasound system during reception is called…
Digitizing
A to D converter
D to A converter
Post processing
A to D converter
150
When the signal is converted from the ultrasound system to the display it uses which of the following?
Digitizing
A to D converter
D to A converter
Post processing
D to A converter
151
When a sonographer zooms in on a particular ROI and the region is rescanned to acquire new information, what is it called?
Post processing
Read magnification
Write magnification
None of the above
Write magnification
152
Which of the following is the disadvantage of a laser or compact disc as storage media?
Stores huge amounts of data
Inexpensive
Requires a display system
Not erased by exposure to magnetic fields
Requires a display system Not erased
153
Which of the following correctly describes a typical television display?
Progressive scan
Interlaced
Bistable
Noninterlaced
Interlaced
154
When changes are made to an image after it is frozen, it is then considered…
Preprocessing or read magnification
Post processing or write magnification
Preprocessing of write magnification
Post processing or read magnification
Post processing or read magnification
155
T/F: Diaphragm movement during respiration causes variations in arterial flow away from the heart.
False
156
In which of the following would you expect to find less resistance to blood flow?
Long narrow segments
Short large segments
At bifurcation
In smaller vessels
Short large segments
157
During inspiration, the pressure in the thoracic cavity ________ and the pressure in the abdomen ________.
Decreases, increases
158
During expiration when the diaphragm moves upward, the venous flow in the lower extremities would…
Increase
159
Which of the following is a prorated of potential energy that provides flow by overcoming resistance?
Pressure energy
Kinetic energy
Gravitational energy
Pressure energy
160
Which of the following types of flow would be seen due to cardiac contraction?
Phasic flow
Pulsatile flow
Steady flow
Pulsatile flow
161
Which of the following would demonstrate the highest resistance waveform?
A large artery
A small artery
A large vein
A small vein
A small artery
162
Which of the following is a correct statement regarding pressure gradient?
A pressure gradient increases when flow or resistance increase
A pressure gradient Increases when flow increases or resistance decreases
A pressure gradient increases when flow decreases or resistance increases
A pressure gradient increases with flow or resistance decrease
A pressure gradient increases when flow or resistance increase
163
How is blood flow related to resistance?
Directly proportional
Inversely proportional
Indirectly related
Unrelated
Inversely proportional
164
Which of the following is not a force that opposes blood flow and is not a major source of resistance?
Vessel diameter
Vessel length
Friction
Blood viscosity
Oxygen content
Oxygen content
165
Which one has the lowest mechanical index?
Fundamental imaging
Harmonic imaging
Fundamental imaging
166
What would be the harmonic frequency of a 2 MHz transducer?
4 MHz
167
T/f: Contrast harmonics are created during reflection by nonlinear behavior, related to MI, and determined by the contrast agent.
True
168
T/f: When using contrast harmonics, the mechanical index will increase with lower frequencies and higher pressure.
True
169
Contrast agents are also known as?
Microbubbles
Shells
Reflections
Energy
Microbubbles
170
An image created by reflectors at two times the transmitted frequency is called a __________.
Harmonic image
Fundamental image
Tissue Doppler
Contrast
Harmonic image
171
Which of the following statements are correct about dynamic range?
Narrow DR, more shades of gray, high contrast
Wide DR, more shades of gray, low contrast
Narrow DR, fewer shades of gray, low contrast
Wide DR, fewer shade of gray, high contrast
Wide DR, more shades of gray, low contrast
172
A signal that is too weak for the system to record is said to no meet the systems
Saturation
Threshold
Accuracy
Range equation
Threshold
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