strongly echogenic surface results in a dark acoustic shadow distal to the probe; US is reflected and absorbed. colonic fecal material, bone, cystic calculi

dirty shadowing, reverberation

occurs because of reflection of US between a strong reflector and the probe; results in additional reflectors that are not real. equally spaced and get weaker.

type of reverberation artifact; origiantes between two anatomic reflecting surfaces with a large difference in acoustic impedence. series of closely spaced, discrete echoes that weaken with increasing depth

similar to comet tail; but no discrete echoes, extends to the bottom of the image without fading. caused by reflection of bubbles in the tissue

mirror image artifact

duplicate structure placed deep to a highly reflective surface. Distal Accoustic Enhancement: increased echogenicity of tissue deep to a fluid-filled structure. caused by decreased US attentuation

slice thickness artifact

the beam partially contacts the surface or wall of an organ, giving the false impression that there is sludge in the organ

what are side/grating lobes?

beams that propagate from a single element (side lobes) or several element (grating lobes), in directions different from the primary beam

occurs as the US beam enters a circular region of higher propogation speed, is refracted, and is then refracted again as it leaves the region

weak echoes due to spreading of the beam and are misplaced deep to the circular structure.

urinary bladder pseudolesion

you can usually tell it's an artifact by moving the probe and evaluating from a different location, and also because the bladder looks otherwise full and normal

results in deviation of the beam and an increase in distance traveled before it is reflected by the cartilage-bone interface. this results in an apparent increase in cartilage thickness

propagation speed error

occurs when the assumed value for propagation speed is incorrect. structures are displaced axially

flow velocity exceeds the computers ability to correctly measure it; spectral - wring side of baseline color flow - wrong color

observed at strongly reflecting scattering surfaces with rough or irregular surfaces. quickly fluctuating mixture of doppler signals with an associated characteristic spectrum of noise. add'l sonographic feature of urinary stones.

echo amplitude is highly dependent on angle of insonation; highest amplitude echoes occur when us beam is 90 to the reflector

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ultrasound-artifacts

Question	Answer
clean shadowing	strongly echogenic surface results in a dark acoustic shadow distal to the probe; US is reflected and absorbed. colonic fecal material, bone, cystic calculi
dirty shadowing, reverberation	occurs because of reflection of US between a strong reflector and the probe; results in additional reflectors that are not real. equally spaced and get weaker.
comet tail	type of reverberation artifact; origiantes between two anatomic reflecting surfaces with a large difference in acoustic impedence. series of closely spaced, discrete echoes that weaken with increasing depth
ring down artifact	similar to comet tail; but no discrete echoes, extends to the bottom of the image without fading. caused by reflection of bubbles in the tissue
mirror image artifact	duplicate structure placed deep to a highly reflective surface. Distal Accoustic Enhancement: increased echogenicity of tissue deep to a fluid-filled structure. caused by decreased US attentuation
slice thickness artifact	the beam partially contacts the surface or wall of an organ, giving the false impression that there is sludge in the organ
what are side/grating lobes?	beams that propagate from a single element (side lobes) or several element (grating lobes), in directions different from the primary beam
edge shadowing	occurs as the US beam enters a circular region of higher propogation speed, is refracted, and is then refracted again as it leaves the region
edge shadowing 2	weak echoes due to spreading of the beam and are misplaced deep to the circular structure.
urinary bladder pseudolesion	you can usually tell it's an artifact by moving the probe and evaluating from a different location, and also because the bladder looks otherwise full and normal
refraction artifact	results in deviation of the beam and an increase in distance traveled before it is reflected by the cartilage-bone interface. this results in an apparent increase in cartilage thickness
propagation speed error	occurs when the assumed value for propagation speed is incorrect. structures are displaced axially
doppler aliasing	flow velocity exceeds the computers ability to correctly measure it; spectral - wring side of baseline color flow - wrong color
twinkling artifact	observed at strongly reflecting scattering surfaces with rough or irregular surfaces. quickly fluctuating mixture of doppler signals with an associated characteristic spectrum of noise. add'l sonographic feature of urinary stones.
anisotropism	echo amplitude is highly dependent on angle of insonation; highest amplitude echoes occur when us beam is 90 to the reflector
electronic noise artifact	should know it when you see it
loss of contact	dark shadow from top of image

Created by: kontakte

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