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Flashcards in Chapter 6 Deck (14)
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1
Q

Aliasing

A

Improper Doppler shift info from a pulsed spectral Doppler or color Doppler instrument when the true Doppler shift exceeds one half the PRF

2
Q

Anechoic

A

Echo free

3
Q

Comet tail

A

a series of closely spaced reverberation echoes

4
Q

Cross talk

A

leakage of strong signals in one direction channel of a Doppler receiver into the other channels; can produce the spectral Doppler mirror image artifact

5
Q

Enhancement

A

Increase in echo amplitude from reflectors that lie behind a weakly attenuating structure

6
Q

Hypoechoic

A

having relatively weak echoes. opposite of hyperechoic

7
Q

Mirror image

A

an artifactual gray scale, color flow, or Doppler signal appearing on the opposite side of a strong reflector

8
Q

Nyquist limit

A

the Doppler shift freq above which aliasing occurs; one half of the PRF

9
Q

Range ambiguity

A

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

10
Q

Reverberation

A

multiply reflections

11
Q

Shadowing

A

reduction in echo amplitude from reflectors that lie behind a strongly reflecting or attenuating structure

12
Q

Slice thickness

A

thickness of the scanned tissue volume perpendicular to the scan plane; also called section thickness

13
Q

Speckle

A

the granular appearance of images and spectral displays that is caused by the interference of echoes from the distribution of scatters in tissue

14
Q

Speed error

A

propagation speed that is different from the assumed value