Chapter 6 Flashcards
Aliasing
Improper doppler shift info from a pulsed spectral doppler or color doppler instrument when the true color doppler shift exceeds one half the PRF
Anechoic
Echo free
Comet Tail
A series of closely spaced reverberation echoes
Enhancement
Increase in echo amplitude
Hypoechoic
Having relatively weak echoes
Mirror Image
An artifactual gray scale, color flow, or doppler signal appearing on the opposite side
Nyquist Limit
The doppler shift frequency above which aliasing occurs
Range Ambiguity
An artifact produced when echoes are placed too close to the transducer because a second pulse was emitted before they were received from the first pulse
Shadowing
Reduction in echo amplitude from reflectors that lie behind a strongly reflecting or attenuating surface
Slice Thickness
Thickness of the scanned tissue volume perpendicular to the scan plane
Speckle
The granular appearence of images and spectral displays that is caused by the interference of echoes from the distribution of scatterers in the tissue
Speed Error
Prop speed that is different from the assumed value
