in color doppler when does gain mimic the absence of flow (little to no flow seen in vessel)
when the gain settings are too low
when effect does gain being set too high have on a vessel?
color will appear outside the vessel and will bleed over other vessels
what will improve an image if the flow is a little patchy?
increasing the persistence
when do you want to increase wall filter?
when color is up to the vessel wall and a little out of the wall
when you see low level doppler shifts or clutter
when do you want to increase your scale or PRF?
when color is abruptly changing, showing signs of aliasing you want to increase you scale or PRF
because aliasing is showing signs that scale is too low and flow is exceeding nyquist limit
when do you want to decrease your scale or PRF?
when you see little to no flow , although high color scale can eliminate aliasing, too high can make it seem as if there is no flow
what is the relationship of PRF and depth?
inversely related
what can be reasons that a vessel is missing flow?
scale, nyquist limit, wall filter, or PRF are too high
what does increasing color gain or persistence help with
can help fill a vessel that isn’t completely filled
what is persistence or temporal average/compounding?
the machine remembers recent frames and blends them together
what does persistence helps with?
reducing noise
smoothes image
improves apparent contrast resolution
what does it mean when you see mirroring artifact?
it means that your gain is too high
how do you fix mirroring artifact?
change your view or change your angle
what often creates twinkle artifact/color comit tail?
very bright reflectors (e.g. stones or gas)
detected with color and spectral doppler
how do you fix twinkle artifact or color comit tail?
take a different view
what does ghosting artifact refer to?
color display outside the vessel within the tissue
how do you fix ghosting artifact?
increase wall filter
what is ghosting artifact occasionally described as?
a flash artifact secondary to motion
if tissue vibration is a result from tissue motion what does it mean?
that it is not truly an artifact and may provide diagnostic clues
ex: in a dialysis graft, tissue vibration is normal
in normal laminar flow what kind of window would you like to see in spectral doppler?
clear spectral windows
what does it mean once you began to see no spectral window?
the spectral window is being filled with a wider range of frequencies = spectral broaden
how do you fix spectral broadening?
decrease your sample volume
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Doppler44
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Optimizing doppler images22
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Imaging processing & display53
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Doppler shift*15
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Inspiration vs Expiration venous blood flow6
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Apply doppler48
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Lateral resolution*11
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Coded excitation*5
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Wall filter8
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Ergonomics6
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Dynamic range8
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Temporal resolution*16
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Artifacts25
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Mock 466
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Mock 363
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Mock 236
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Pulse repetition frequency*15
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Duty factor *7
