Term
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Definition
Echoes appearing on the sonographic image which do not correspond to the actual structure in the patient. Incorrect representation of anatomy or motion. Appear in some views and disappear in others vs. actual anatomy which is always visible
Some artifacts are produced by improper equipment operation or setting ( incorrect gain settings) |
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Term
| Artifacts include reflections that are: |
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Definition
No real
missing/not seen on the image
not in the correct position/improperly located
not the correct brightness
not the correct shape or size |
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Term
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Definition
| In order for programming of the ultrasound machine to work.The machine uses certain "facts" to determine what the "information" that the returning echo represents |
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Term
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Definition
| The transmitted wave travels along a straight-line path from the transducer to the object and back to the transducer. |
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Definition
| The imaging plane is very thin and reflected echoes only come from structures located in the beam's main axis. |
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Definition
2D
all signals are from XY axis only |
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Term
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Definition
| The amplitude(strength) of the reflected sound is related to the characteristics of the tissue creating the reflection. |
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Definition
| the ultrasound wave travels in soft tissue at a constant rate of 1540m/s in tissue and that the distance to the reflector is proportional to the round trip travel time 13us/cm of depth |
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Term
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Definition
| The attenuation of sound in tissue is equal along the path all echoes come from most recent pulse |
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Term
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Definition
Violation of assumptions
operator error
equipment malfunction |
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Term
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Definition
Lateral resolution
Axial resolution |
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Term
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Definition
| The ability to clearly identify two structures that are very close together when the structures are side by side( or perpendicular to the sound beam). Lateral resolution is determined by the width of the sound beam. Narrower beams have better resolution. |
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Term
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Definition
Is its best at the focus where the beam is the narrowest.
Two structures that are next to each other ( perpendicular) to the sound beam. |
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Term
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Definition
| Describes the ability to display 2 structures that are very close together when they are parallel to the sound beam. It is the ability to clearly identify two reflectors when they are positioned one in front ( on top) of the other |
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Term
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Definition
Is determined by SPL
Spatial pulse length
Shorter pulse improved axial resolution. |
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Term
| Higher frequency transducers: |
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Definition
Improve both axial and lateral resolution.
Higher frequency produces shorter pulse Short SPL which gives us better axial resolution. Higher Frequency sound beams are narrower( diverge less) and therefore have better lateral resolution. |
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Term
| Better Lateral resolution: |
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Definition
Image side by side ( perpendicular)
High frequency beams Narrowest diverge less |
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Term
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Definition
Image one in front of the other ( parallel)
SPL
Higher frequency Shorter pulses
Shorter SPL |
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Definition
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Definition
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Term
Section Thickness artifact
AKA Partial Volume Artifact |
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Definition
Beam width perpendicular to the scan plane("Thickness" of the beam) may cause section thickness artifacts.
Echoes from the "thickness" of the beam are collapsed into a flat image.
Visualization of false debris in echo free areas. |
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Term
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Definition
It is caused by small amplitude sound waves interfering with each other( constructive and destructive interference of echoes returning simultaneously from many scatterers
Tissue appears "Grainy"
Salt and pepper |
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