Artifacts

Question 1

Multiple equally spaced echoes caused by the bouncing of the sound wave between two strong reflectors positioned parallel to us beam

Answer 1

Reverberation

Question 2

Reverberation resembles a

Answer 2

Ladder

Question 3

Solid hyperechoic line directed downward. Created when closely spaced reverberations merge.

Answer 3

Comet tail

Question 4

Appears when a sound wave bounces back and forth between two verily closely spaced objects

Answer 4

Comet tail

Question 5

Hypoechoic or anechoic region appears when attenuation is higher

Answer 5

Shadow

Question 6

Shadowing is unrelated to ___ in a medium

Answer 6

Speed of sound

Question 7

Hypoechoic region extending down from the edge of a curved reflector caused by a decrease in intensity

Answer 7

Edge shadowing / shadowing by refraction

Question 8

Hyperechoic beneath tissues with low attenuation

Answer 8

Enhancement

Question 9

Special form of enhancement, in which a side to side region of an image appears brighter than tissues, that other depths

Answer 9

Focal enhancement / focal banding

Question 10

Focal enhancement results from ____ at the focus

Answer 10

Increased intensity

Question 11

This artifact is located deeper than the real structure. Sound reflects off a strong reflector and is redirected toward a second structure.

Answer 11

Mirror image

Question 12

6 assumptions of imaging systems

Answer 12

1) sound travels in a straight line
2) sound travels directly to reflector
3) sounds travels at 1540 m/s
4) imaging plane is very thin
5) reflections arise only from structures positioned in the beams main axis
6)the strength of the reflection is related to characteristics of the tissue creating the reflection

Question 13

Useful artifacts

Answer 13

shadowing and enhancement

Question 14

Mirror image artifact that appears on a spectral doppler display

Answer 14

crosstalk

Question 15

Appears as a step off and created when a sound wave propogates through a medium at a speed other than 1.54 mm/us

Answer 15

Speed error

Question 16

There a correct number of reflectors but has an improper debth

Answer 16

speed error

Question 17

When sound energy is transmitted in a direction other than along the beams main axis

Answer 17

lobe artifact

Question 18

lobe artifact degrades

Answer 18

temporal resolution

Question 19

Lobes created by a single crystal transducer such as a mechanical probe

Answer 19

side lobes

Question 20

lobes created by array transducers are

Answer 20

grating lobes

Question 21

Reducing lobe artifacts in 2 ways

Answer 21

subdicing and apodization

Question 22

dividing each pzt element into small pieces

Answer 22

subdicing

Question 23

Process of differential excitation.
exiting the subdiced elements with a different voltage

Answer 23

apodization

Question 24

Created when a sound pulse changes direction during transmission and occurs when a sound wave strikes a boundary obliquely

Answer 24

Refraction

Question 25

Refraction degrades

Answer 25

lateral resolution

Question 26

side by side or same depth of the true reflector

Answer 26

Refraction

Question 27

Slice thickness is also called

Answer 27

section thickness artifact / partial volume artifact

Question 28

Related to the dimension of the beam that is perpendicular to the imaging plane

Answer 28

Slice thickness artifact

Question 29

Determined by the thickness of the imaging plane

Answer 29

Elevation resolution

Question 30

Anatomic reflectors absent on an image

Answer 30

shadowing, lateral resolution, axial resolution

Question 31

Artifact positioned deeper than true anatomy

Answer 31

comet tail, ring down, reverberation, mirror image

Question 32

Artifacts displayed to the side of true anatomy

Answer 32

refraction, side lobe, grating lobe

Question 33

Anatomic structures appear at incorrect depth

Answer 33

Speed errors, range ambiguity artifact

Question 34

Which artifact is unrelated to the dimensions of an us pulse

Answer 34

refraction

Question 35

It is common to visualize artifacts when the dimension of the sound beam is ____ than the reflectors dimension

Answer 35

Larger

Question 36

Which artifact produced an image with an incorrect number or reflectors

Answer 36

Side lobes

Question 37

What determines spatial resolution of a digital display

Answer 37

pixel density

Question 38

What determines spatial resolution of a display

Answer 38

Number of lines on the display

Question 39

Lateral resolution can be approved by

Answer 39

focusing because it narrows the beam width

Question 41

Low line density degrades

Answer 41

spatial resolution

Question 42

What alters low velocity flows while leaving high velocity flow unchanged

Answer 42

Wall filter

Question 43

Alter low velocity flows while leaving high velocity flow unchanged

Answer 43

Wall filter

Question 44

What determines the spatial resolution in a digital display

Answer 44

Pixel density

Question 45

This artifact produces an image with an incorrect number of reflectors

Answer 45

Side lobes

Question 46

What happens to the position of all echoes produced from reflectors shallower than the mass

Answer 46

They are placed at the correct depth

Question 47

What happens to the position of echoes from reflectors deeper than the mass

Answer 47

They are placed in too deep a location on the image

Question 48

What type of artifact causes a reflection to be placed at an incorrect depth

Answer 48

Range ambiguity

Question 49

Acoustic energy radiating in a direction other than the beams main axis causes

Answer 49

Side lobe artifact

Question 50

Grating loves are most common with what transducers

Answer 50

Linear array

Question 51

Technique to eliminate grating lobe artifact

Answer 51

Subdicing

Question 52

How does slice thickness express itself

Answer 52

Fill in cystic structures

Question 53

With depth resolution there are ___ reflectors on the image

Answer 53

Too few

Question 54

What is a comet tail artifacts fundamental mechanism of formation

Answer 54

Reflection

Question 55

What haze the higher value / axial or lateral

Answer 55

Lateral

Question 56

When do artifacts appear

Answer 56

When the dimensions of a sound beam area is larger than the dimensions of the reflectors in the body