LEC 8 - UTZ ARTIFACTS

Question 1

A structure in an image which does not directly correlate with actual tissue being scanned.

Answer 1

ULTRASOUND ARTIFACTS

Question 2

Any part of an image does not accurately represent the anatomic structures present within the subject being evaluated

Answer 2

ULTRASOUND ARTIFACTS

Question 3

Artifacts assume different forms, including:

Answer 3

a. Structures in the image that are not actually present.
b. Objects that should be represented but are missing from the image.
c. Structures which are misregistered on the image.

Question 4

Commonly occurring artifacts:

Answer 4

a. Reverberation
b. Acoustic shadowing
c. Acoustic enhancement
d. Edge shadowing
e. Side lobe artifact
f. Mirror image artifact

Question 5

• The production of spurious (false) echoes due to repeated reflections between two interfaces with a high acoustic impedance mismatch.

Answer 5

1. REVERBERATION ARTIFACT

Question 6

Are a form of reverberation artifact that appear as a dense tapering V-shaped trail of echoes beyond strong reflectors.

Answer 6

Comet tail artifacts

Question 7

Short-range rapid reverberations, which can occur between the walls of a hollow structure or metallic object, produce _.

Answer 7

Comet tail artifacts

Question 8

Are reverberation echoes similar to comet tail artifacts except that the bright artifactual echoes are displayed in a much longer stream.

Answer 8

Ring-down artifacts

Question 9

A line of bright continuous echoes is seen deep to a strong reflector.

Answer 9

Ring-down artifacts

Question 10

To help eliminate reverberation artifact, it may be useful to:

Answer 10

a) Increase the amount of gel used.
b) Use a stand-off pad (such as a commercially produced gel pad or a bag of saline)
c) Reduce the gain.
d) Move the position of the transducer.

Question 11

• This area appears an area of low amplitude echoes (hypoechoic or anechoic) behind an area of strongly attenuating tissue.

Answer 11

2. ACOUSTIC SHADOWING

Question 12

Some interfaces causing such effects are:

Answer 12

 Soft tissue/gas (bowel, lung)
 Soft tissue/bone, calcium (ribs, calculi)
 Normal tissue/fibrous tissue (scars, ligaments)

Question 13

Shadows from calcium and bone are usually are echo free

Answer 13

clean

Question 14

Shadows from gas are often partially filled with reverberations

Answer 14

dirty

Question 15

This artifact appears as localized area of increased echo amplitude behind an area of low attenuation.

Answer 15

3. ACOUSTIC ENHANCEMENT

Question 16

On a scan it will appear as an area of increased brightness, and can commonly seen distal to the fluid filled structures such as urinary bladder, the gallbladder or a cyst.

Answer 16

3. ACOUSTIC ENHANCEMENT

Question 17

A combination of refraction and reflection occurring at the edges of rounded structures and when the speed of sound is different from that in surrounding tissue will result in an edge shadowing artifact.

Answer 17

4. EDGE SHADOWING

Question 18

This artifact is caused by low energy “side lobes” of the main ultrasound beam.

Answer 18

5. SIDE LOBE ARTIFACT

Question 19

Are usually seen in hypoechoic or echo-free structures and appear as bright and rounded line.

Answer 19

5. SIDE LOBE ARTIFACT

Question 20

These artifacts result in a mirror image of a structure occurring in an ultrasound display. They arise due to specular reflection of the beam at a large smooth interface.

Answer 20

6. MIRROR IMAGE ARTIFACT

Question 21

• Structures displayed twice, with one being a mirror of the other. An area close to a specular reflector will be imaged twice, once by the original ultrasound beam and once by the beam after it has reflected off the specular reflectors.

Answer 21

6. MIRROR IMAGE ARTIFACT

Question 22

• Echoes return along the same path from the reflecting surface, back to the transducer. Because the equipment assumes all echoes arise from a straight beam, the reflected echoes are displayed in a line as if originating from below the specular reflecting surface.

Answer 22

6. MIRROR IMAGE ARTIFACT

Question 23

Example of these are (mirror image artifact):

Answer 23

a) Diaphragm/Lung interface

b) Bladder/Rectum interface, when the rectum is gas filled.