Ch. 21 Artifacts

appears in mulitples

reverberation

appears equally spaced

reverberation

located parallel to sound beam’s main axis

reverberation, comet tail

located at ever-increasing depths

reverberation

appears as a single long hyperechoic echo

comet tail

hypo- or anechoic (background color)

shadowing; edge shadow

result of too much attenuation

shadowing

located beneath the structure with abnormally high attenuation

shadowing

prevents visualization of true anatomy on the scan

shadowing; edge shadow

results when the beam spreads after striking a curved reflector

edge shadow

extends downward from the curved reflector’s edge, parallel to beam

edge shadow

hyperechoic (appears the same as the foreground color)

enhancement

result of too little attenuation

enhancement

located beneath a structure with abnormally low attenuation

enhancement

hyperechoic side to side region (appears the same as the foreground color)

focal enhancement

results from increased intensity at the focus

focal enhancement

second copy of true reflector

mirror image; lobes

artifact appears deeper than the true reflector

mirror image

bright reflector lies on a straight line between the artifact and the transducer

mirror image

true reflector and artifact are equal distances from each other

mirror image

sound travels slower than the US system expects

speed error (medium’s speed is too slow)

pulses return from their trip in the body slow

speed error (medium’s speed is too slow)

go return time is too long

speed error (medium’s speed is too slow)

system assumes reflectors are far from transducer

speed error (medium’s speed is too slow)

reflectors places too deep on image

speed error (medium’s speed is too slow)

distances are overestimated (reporter number is too large)

speed error (medium’s speed is too slow)

sound travels faster than the US system expects

speed error (medium’s speed is too fast)

pulses return from their trip in the body fast

speed error (medium’s speed is too fast)

go return time is too short

speed error (medium’s speed is too fast)

system assumes reflectors are close to transducer

speed error (medium’s speed is too fast)

reflectors are located too shallow on image

speed error (medium’s speed is too fast)

distances are underestimated (reported number is too small)

speed error (medium’s speed is too fast)

the artifact and the true reflector are located side by side at the same depth

lobes

a second copy of the reflector

refraction

the copy is side by side or at the same depth as the true reflector

refraction