Chapters 1-4 Flashcards
(118 cards)
1
Q
What’s the basic beam profile?
A
transducer -> near field -> focal zone -> far field
2
Q
What’s another word for near field?
A
Fresnel
3
Q
What’s another word for far field?
A
Fraunhofer
4
Q
Define the focal zone.
A
The focal zone is the region around the focus where the beam is relatively narrow.
Reflections from the focal zone create images that are more accurate than from other depths.
5
Q
Depth of view
A
Describes the maximum distance into the body than an ultrasound system is imaging.
The markers along the edge of an image indicate depth.
6
Q
Define gain.
A
Receiver gain increases the amplitude of the returning signals
This creates a brighter image
7
Q
Define TGC.
A
Time Gain Compensation) adjusts gain according to depth
8
Q
Can transducers change from one frequency to another?
A
Yes. The Transducer is capable of switching from one frequency to another by changing the frequency of the “transmitter” voltage.
9
Q
What is Spatial Resolution?
A
Spatial resolution refers to how closely positioned two reflectors can be to one another and still be resolved as two different objects on the display
When structures are displayed as separate images we say that they are resolved
10
Q
What are 3 resolutions included in spatial resolution?
A
axial, lateral, and slice thickness resolution
These 3 resolutions are listed from best to worst
11
Q
What does image resolved mean?
A
objects have good resolution. aka the two objects can easily be told apart.
12
Q
What are the other names of Axial resolution?
A
L-A-R-R-D Longitudinal Axial Range Radial Depth
13
Q
Which direction is the axial resolution?
A
The y axis. From anterior to inferior. aka one above the other.
14
Q
What are the other names of Lateral Resolution?
A
L-A-T-A Lateral Angular Transverse Azimuthal
15
Q
What direction is lateral resolution?
A
x axis. From right to left. aka side by side
16
Q
What is lateral resolution determined by?
A
Lateral resolution is determined by the beam width
A narrow beam width gives a good lateral resolution
17
Q
What is Temporal resolution.?
A
The ability to depict the movement of structures accurately
Temporal resolution is very important in the depiction of moving objects, such as the heart
Temporal resolution is determined by the frame rate
If frame rate increases, so does the temporal resolution. Because more frames gives a better view like in tvs.
18
Q
What do multiple focal zones do?
A
decrease temporal resolution
improve lateral resolution
increase sensitivity of the sound beam
make the overall beam thinner
19
Q
Name the abdominal regions in their correct location/.
A
right hypochondrium, epigastrium, left hypochondrium.
right lumbar, umbilical region, left lumbar.
right iliac, hypogastrium, left iliac.
20
Q
Name the abdominal quadrants correctly. And which organs are located in each of them.
A
right upper quandrant, left upper quandrant.
right lower quadrant, left lower quandrant.
21
Q
Name body planes and directional terms.
A
Coronal plane. sagittal plane. transverse plane. lateral. medial. distal. proximal. superfical. deep. anterior. posterior.
22
Q
Name directions of the sagittal plane on monitor.
A
anterior (on top) and posterior (bottom).
superior (on left) and inferior (on right).
23
Q
Name directions of the transverse plane on monitor.
A
anterior (top) and posterior (bottom).
right (left) and left (right).
24
Q
Acoustic enhancement
A
enhancement“Increased echo amplitude” or “posterior through transmission” visualized posterior to a structure that does not attenuate (decrease, stop, impede, or absorb) the sound beam. Considered a type of sonographic artifact.
25
Acoustic impedance
The resistance a material provides to the passage of sound waves.
26
Acousting shadows (shadowing)
“Reduced echo amplitude” or echo “drop off” posterior to a structure that attenuates (decreases, stops, impedes, or absorbs) the sound beam. Margins of the shadow are generally sharp and well defined. Considered a type of sonographic artifact.
27
ALARA
as low as reasonably achievable.
The prudent use of diagnostic sonography; dictates that the output level and exposure time to ultrasound is minimized while obtaining diagnostic data.
28
Anechoic
Term used to describe an echo-free appearance on a sonographic image.
29
Anterior/ventral
Situated at or directed toward the front.A structure in front of another structure.
30
Artifact
Image artifacts are echo features or structures observed on ultrasound images that are unassociated with the object being imaged.
31
Ascites
Accumulation of serous fluid anywhere in the abdominopelvic cavity.
32
Attenuation
Decrease in the intensity of the sound beam as it passes through a structure, caused by absorption, scatter, or beam divergence.
33
Axial
At right angles to longitudinal sections. Term used to describe the section of a structure portrayed within a scanning plane image.
34
Beam divergence
Widening of the sound beam as it travels.
35
Calipers
Two or more measurement cursors that can be manipulated to calibrate the distance between echoes of interest on the imaging screen.
36
Color flow Doppler
Doppler shift information in a two-dimensional presentation superimposed on a real-time gray-scale anatomic cross-sectional image.
Flow directions are presented as different colors on the ultrasound display screen.
37
Complex mass
Abnormal mass within the body that is composed of both tissue and fluid.
38
Calculi/stones
Concentration of mineral salts that may accompany some disease processes.
some disease processes.Calculi are often visualized within the gallbladder as bright, movable structures that vary in size and cast posterior shadows.
39
Contralateral
Situated on or affecting the opposite side.
| The ovaries are contralateral organs.
40
Contrast
A comparison to show differences.
41
Coronal scanning planes
Any plane parallel to the long axis of the body and perpendicular to sagittal scanning planes.
42
Coupling agent
Substance used to reduce air between the ultrasound transducer and surface of the skin.
Gel is a typical coupling agent used in sonography.
43
Crura of diaphragm
Right and left crus or fibromuscular bands arising from the lumbar vertebrae that insert into the central tendon of the diaphragm.
44
Cystic
Describes the sonographic appearance of a fluid collection within the body that does not meet the criteria to be considered a true cyst.
45
Deep
Internal.Situated away from the surface.
46
Depth of penetration
Maximum distance the sound beam travels from the transducer through a medium.
47
Diffuse disease
Infiltrative disease throughout an organ that disrupts the otherwise normal sonographic appearance of organ parenchyma.
48
Distal
Situated farthest from the point of origin.
49
Doppler effect
Change in observed sound frequency caused by relative motion between the source of the sound or reflector and the observer.
Doppler is used to detect blood flow through vessels. It detects not only the presence of flow but also the direction of flow by measuring the difference in the frequency of the reflected sound compared with the transmitted sound.
50
echogenic
Describes a structure that is able to produce echoes or echo patterns on sonograms.
51
Echopenic
Few echoes.
52
Echo texture
Describes the sonographic appearance of soft tissue structures within the body.
Normal organ parenchyma (soft tissue) is characterized sonographically as homogeneous or uniform in echo texture. If disrupted or changed by disease, the parenchyma typically assumes an irregular or heterogeneous echo texture or pattern. The nature of this change may be diffuse disease (infiltrative; focal) or localized disease (a mass or multiple masses circumscribed to a specific area).
53
Extraorgan pathology
Abnormal disease process that originates outside of an organ.
54
Focal/multifocal change
Disease process confined to isolated area(s) of an organ.
55
Focal zone
The point at which the sound beam is the narrowest and the resolution is the best.
Different transducers have different depths where their focus or focal zone is optimal. Therefore, the depth of a structure (of interest) within the body determines which transducer should be used.
56
Gray scale
Sonographic display format where echo amplitude (intensity) is recorded and presented as variations in brightness of shades of gray.
57
Heterogeneous
Describes an irregular or mixed echo pattern on a sonographic image.
58
Homogeneous
Describes uniform or similar echo patterns on a sonographic image.
59
Hyperechoic
Comparative term used to describe an area in a sonographic image where the echoes are brighter or more intense compared to surrounding structures.
60
Hypoechoic
Comparative term used to describe an area in a sonographic image where the echoes are not as bright compared to surrounding structures.
61
Inferior/caudal
Toward the feet.Situated below or directed downward.A structure lower than another structure.
62
Infiltrative disease
Diffuse disease process that spreads throughout an entire organ.
63
Interface
The boundary between two materials or structures.
| Use the bright sonographic appearance of fat interfaces to differentiate body structures from each other.
64
Intraorgan pathology
Abnormal disease process that originates within an organ.
65
Intraperitoneal
```
Abdominopelvic structures enclosed in the sac formed by the parietal peritoneum.
The liver (except for the bare area posterior to the dome), gallbladder, spleen (except for the hilum), stomach, the majority of the intestines, and the ovaries are considered intraperitoneal.
```
66
Ipsilateral
Situated on or affecting the same side.
| The spleen and left kidney are ipsilateral.
67
Isogenic/isosonic
Comparative term used to describe an area in a sonographic image where the echo patterns are equal in echogenicity.
68
Lateral
Pertaining to the right or left of the middle or midline of the body. Describes a structure situated at, on, or toward the side.
69
localized disease
Represents a circumscribed mass or multiple masses.
70
long axis
Represents the longest length of a structure.
71
Longitudinal
Pertains to length; running lengthwise.
72
Mass
Circumscribed disease process.
73
Medial
Situated at, on, or toward the middle or midline of the body.
74
Medium
Any material through which sound waves travel.
| Most fluid collections are nonattenuating mediums, whereas bone is an attenuating medium.
75
Mesentery
A double fold of peritoneum that connects intraperitoneal organs to the abdominal cavity wall.
76
sagittal scanning planes
Any plane parallel to the long axis of the body and perpendicular to coronal scanning planes.
77
Mirror image artifact (non-doppler)
The sonographic image of a structure is duplicated in an atypical position and appears as a mirror image of the original.
78
Necrotic
Degeneration or “death” of tissue.
79
Neoplasm
New, abnormal growth of existing tissues; either benign or malignant.
80
Orthogonal
At right angles; perpendicular.
| Coronal planes are orthogonal to sagittal planes.
81
Parenchyma
Tissue composing an organ.
| Normal organ parenchyma appears homogeneous on an ultrasound image.
82
Peritoneum
Thin sheet of tissue that lines the peritoneal cavity and secretes serous fluid, which serves as a lubricant and facilitates free movement between organs. Classified as parietal (portion of lining that forms a closed sac) and visceral (portion of lining that directly covers organs and various body structures). Characterized as intraperitoneal (inside the sac) and retroperitoneal (posterior or behind the sac).
Structures enclosed and generally covered by peritoneum include the liver, gallbladder, spleen, stomach, majority of the intestines, and ovaries. Structures behind and only anterior surfaces are covered by peritoneum include the pancreas, inferior vena cava, abdominal aorta, urinary system, colon, and uterus.
83
Pleural effusion
A collection of fluid inside the lung.
| A pleural effusion appears anechoic and hypoechoic relative to the bright appearance of adjacent ribs.
84
Posterior/dorsal
Situated at or directed toward the back. A structure behind another structure.
85
Proximal
Situated closest to the point of origin or attachment.
86
Retroperitoneum
Area of the abdominopelvic cavity located behind or posterior to the peritoneum.
Structures posterior to the peritoneum include the pancreas, inferior vena cava, abdominal aorta, urinary system, adrenal glands, colon, and uterus. Only their anterior surfaces are in contact with the parietal peritoneal lining.
87
Reverberation
Ultrasound image artifact caused when sound waves pass through and beyond a structure whose acoustic impedance is noticeably different from an adjacent structure, causing a huge amount of reflection back to the transducer.
88
Septations
Thin, membranous inclusion(s) within a mass.
89
Solid mass
Abnormal mass within the body composed of one thing, tissue.
90
Superficial
External.Situated on or toward the surface.
91
Superior/cranial
Toward the head.Situated above or directed upward.A structure higher than another structure.
92
Systemic
Pertains to the body as a whole.
93
TGC (time-gain compensation)
Increase in receiver gain with time to compensate for loss in echo amplitude, usually due to attenuation, with depth.
94
Through transmission
“Increased echo amplitude” or “acoustic enhancement” visualized posterior to a structure that does not attenuate (decrease, stop, impede, or absorb) the sound beam. Considered a type of sonographic artifact.
A true cyst must exhibit posterior through transmission.
95
Transmission
Term implying passage of energy through a material
96
Transverse scanning planes
Any plane perpendicular to the long axis of the body.
97
True cyst (simple cyst)
Abnormal mass within the body composed of fluid
98
Transducer/probe
A device capable of converting electrical energy to mechanical energy, and vice versa.
99
What does the design of the transducers assume? What happens if any of these assumptions gets violated?
Sound travels in a straight line.
Echoes originate from objects located on the beam axis.
Amplitudes of returning echoes are related directly to the echogenicity of the objects that produced them.
Distance to echogenic objects is proportional to the round-trip travel time (13 µs/cm of depth).
If any of these assumptions is violated, an artifact occurs.
100
Name propagation artifacts.
```
Section thickness
Speckle
Reverberation
Mirror image
Refraction
Grating lobes
Speed error
Range ambiguity
```
101
Name attenuation artifacts.
Shadowing
| Enhancement
102
Name spectral doppler artifacts.
```
Aliasing
Nyquist limit
Range ambiguity
Mirror image
Noise
```
103
Name color doppler artifacts.
Aliasing
| Mirror image, shadowing, clutter, and noise
104
Increasing frequency improves both resolutions, whereas focusing improves
lateral
105
reverberation results in what?
results in the display of additional reflectors that are not real.
106
What are comet tails?
Comet tail artifacts are caused by closely spaced reverberations.
Comet tail is a particular form of reverberation with closely spaced, discrete echoes.
.
107
Ring down artifact.
Ring-down artifact appears similar to the comet tail but is fundamentally different.
Discrete echoes cannot be identified in a ring-down artifact because continuous emission of sound from the origin appears to be occurring.
This continuous effect is caused by a resonance phenomenon associated with the presence of a collection of gas bubbles.
also a form of reverberation.
108
Mirror-image artifact
Mirror-image artifact is also a form of reverberation.
| This artifact shows structures that exist on one side of a strong reflector as being present on the other side as well.
109
Refraction can cause a reflector to be positioned improperly on a sonographic display in what dimension?
laterally
110
Explain side and grating lobes.
Side lobes
Beams that propagate from a single transducer element in directions different from the primary beam
Grating lobes
Additional beams emitted from an array transducer thatare stronger than the side lobes of individual elements
Side and grating lobes weaker than the primary beam; normally do not produce echoes that are imaged, particularly if they fall on a normally echogenic region of the scan.
If grating lobes encounter a strong reflector such as bone or gas, their echoes may well be imaged, particularly if they fall within an anechoic region.
If this happens, they appear in incorrect locations.
111
speed error
Occurs when the assumed value for propagation speed (1.54 mm/µs, leading to the 13 µs/cm round-trip travel-time rule) is incorrect.
If the propagation speed that exists over a path traveled is greater than 1.54 mm/µs, the calculated distance to the reflector is too small, and the reflector will be displayed too close to the transducer.
Occurs because increased speed causes the echoes to arrive sooner.
If the actual speed is less than 1.54 mm/µs, the reflector will be displayed too far from the transducer because the echoes arrive later.
Refraction and propagation speed error also can cause a structure to be displayed with an incorrect shape.
112
range ambiguity
Sonography assumes that for each pulse, all echoes are received before the next pulse is emitted.
Range ambiguity is an artifact produced when echoes are placed too close to the transducer because a second pulse was emitted before they were received.
The maximum depth imaged correctly by an instrument is determined by its pulse repetition frequency (PRF).
To avoid range ambiguity, PRF automatically is reduced in deeper imaging situations.
This also causes a reduction in frame rate.
113
Shadowing
Shadowing is the reduction in echo amplitude from reflectors that lie behind a strongly reflecting or attenuating structure.
A strongly attenuating or reflecting structure weakens the sound distal to it, causing echoes from the distal region to be weak and thus to appear darker, like a shadow.
Of course, the returning echoes also must pass through the attenuating structure, adding to the shadowing effect.
Examples of shadowing structures include calcified plaque, bone, and stones.
114
enhancement
Enhancement is the strengthening of echoes from reflectors that lie behind a weakly attenuating structure.
Shadowing and enhancement result in reflectors being placed on the image with amplitudes that are too low and too high, respectively.
Brightening of echoes also can be caused by the increased intensity in the focal region of a beam because the beam is narrow there.
This is called focal enhancement or focal banding.
Focal banding can also be caused by incorrect gain and TGC settings.
115
Noise
Noise, generated internally or from external sources like electronic equipment, can also produce artifacts.
116
aliasing
Is the most common artifact encountered in Doppler ultrasound.
The word alias comes from Middle English elles, Latin alius, and Greek allos, which mean other or otherwise.
Aliasing in sonography indicates improper representation of information that has been sampled insufficiently.
117
methods of reducing or eliminating aliasing.
```
Shift the baseline.*
Increase the pulse repetition frequency.*
Increase the Doppler angle.
Use a lower operating frequency.
Use a continuous wave device.
* most common
```
118
What's the most common color doppler artifact?
aliasing
