artifacts
Duplicated structure appearing across a strong reflector at an equal distance
Mirror Image
bright tapering without spacing behind a structure resulting from two parallel strong reflectors
Comet tail
Frame rate calculation
PRF / lines per frame
Preprocessing occurs
Before storage
Persistance reduces
Well take temporal resolution and noise
What artifact is caused by the beam bending
Refraction
Identical Doppler signals above and below baseline
Cross talk
Narrow sector size effects temporal resolution how
Increases frame rate improves temporal resolution
this preprocessing function improves spatial resolution
Write magnification
Spatial compounding and persistence differ how
Persistance averages using the same view spatial compounding uses multiple angles
Which artifact violates ” sound travels in a straight line “
Refraction
Where will the artifact be placed if the sound is traveling slower than expected
Deeper than real structure
Best settings for fast moving structures ( sector size, density)
Narrow sector, low density
Fill in interpolation Improves which resolution
Spatial resolution
What is not reversible
Preprocessinb
False echoes inside a cyst that disappear with tissue harmonics turned on
Elevational resoltuion artifact
Motion based false Doppler signal
Flash artifact
Minimum frame rate to avoid flicker
15 Hz
Persistence is best used for slower or faster moving structures
Slower
Pixel is defined as
Smaller picture element
Energy outside the main beam causes
Side lobe artifact
A structure appears deeper due to a longer sound travel time
Multi path
Multi focusing improves which resolution and degrades which resolution
Improves spatial degrades femporal
4 bits equals how many grey shades
16
What are the two components of demodulation
Smoothing and rectification