Common Artifacts In OB/GYN Sonography

Question 1

Shadowing

Answer 1

Loss of sound distal to a strongly reflective or attenuating structure.

Question 2

Enhancement /increased through transmission

Answer 2

Increased echoes beyond a weakly attenuating structure

Question 3

Reverberation

Answer 3

Bands of echos between two strong parallel reflectors ( generally superficial in an anechoic structure)

Question 4

Comet tail

Answer 4

A type of reverberation ( metal surgical clips )

Question 5

Ring down

Answer 5

A type of reverb seen when fluid is trapped between air bubbles ( bowel gas )

Question 6

Mirror image

Answer 6

Duplication of a structure equidistant from strong reflector ( diagram , bowel gas)

Question 7

Edge effect shadowing

Answer 7

Thin shadowing from rounded structure; due to refocusing in refraction

Question 8

Speed propagation error

Answer 8

Seen beyond structures composed of fat ( ovarian, teratoma ) axial displacement along beam path

Question 9

Refraction

Answer 9

Duplication of a structure lateral to the real structure ( two sacs in signal IUP )

Caused by sound beam striking the rectus abdominus m obliquely

Corrected by changing the transducer location / angle

Question 10

Fill in due to:

Answer 10

Side lobes/ grating lobes / partial volume/averaging

Question 11

Doppler effect

Answer 11

Frequency shift

Question 12

Spectral Doppler

Answer 12

Waveform

Question 13

Color Doppler

Answer 13

Color Flow traveling toward or away from transducer

Question 14

Power Doppler

Answer 14

Amplitude of flow , non directional

Question 15

Harmonic frequency

Answer 15

Double the transmitted frequency

Question 16

Most important ALARA in OB

Answer 16

Keeping output power as low as reasonably achievable (until the end of the 10th week).