Chapter 21 Artificats

Question 1

When creating an ultrasound image, all of the following assumptions are made except?
A: Sound travels in a straight line
b: Sound travels att 1.54 km/s
C: The sound beam is extremely thin
D: All structure create reflectors of equal magnitude

Answer 1

D- All structure create reflectors of equal magnitude

Question 2

Which statement regarding axial resolution is incorrect?
A: Axial resolution artifact is related to beam diameter
B: Higher quality images are associated with similar numbers
C: Axial resolution may be reported in units of meters
D: Numerically, axial resolution equals one-half the pulse length
E: Too few reflectors appear on the image

Answer 2

A: Axial resolution is not related to beam diameter.

Question 3

An ultrasound pulse has a width of 4mm, a length of 2 mm, and is produced by a transducer 3,000 times per second. What is the best estimate of the systems axial resolution?
A: 4mm
B: 2mm
C: 1mm
D: 1,500 Hz

Answer 3

C: 1 mm

Question 4

Which of the following statements is true about lateral resolution?
A: It is also called angular, transverse and depth resolution
B: It is reported in units of time
C: It is the same at all depths
D: It can be improved by focusing

Answer 4

D: It can be improved by focusing

Question 5

All of the following artificats result in the placement of too many echoes on the image except;
A: shadowing
B: reverberation
C: mirror image
D: grating lobes

Answer 5

A: Shadowing

Question 6

Which of the following determines the spatial resolution of a display?
A: number of pixels
B: number of lines on the display
C: number of bits per pixel
D: spatial pulse length

Answer 6

B: number of lines on thee display

Question 7

Which of the following determines the spatial resolution of a digital display?
A: pixel density
B: number of lines on the display
C: number of bits per pixel
D: Spatial pulse length

Answer 7

A: pixel density

Question 8

Which artifact produces an image with an incorrect number of reflectors ?
A: propagation speed error
B: multipath
C: enhancement
D: side lobes

Answer 8

D: side lobes. (Artifacts places a second echo on an image from a single structure)

Question 9

True or false. Mirror image artifacts always appear deeper than the true anatomy

Answer 9

True

Question 10

Which artifact is unrelated to the dimensions of an ultrasound pulse?
A: lateral resolution
B: depth resolution
C: slice thickness
D: refraction

Answer 10

D: Refraction

Question 11

True or false. It is common to visualize artifacts when the dimension of the sound beam is larger than the reflector’s dimension.

Answer 11

True.

Question 12

Propagation artifacts occur when

Answer 12

Bending (refraction), redirection (reflection0 or reverberation of the sound wave

Question 13

Two distinct reflections are observed on an image, but they actually arise from a single anatomical structure. The artifact is positioned deeper than the correct reflection. What is the most likel cause of this artifact.
A: grating lobe
B: side lobe
C: refraction
D: mirror image

Answer 13

D: mirror image

Question 14

Which one of these artifacts does not result from multiple reflections?
A: comet tail
B: reverberations
C: ring down
D: enhancement

Answer 14

D: enhancement

Question 15

What is an artifact ?

Answer 15

An error in imaging

Question 16

Causes of Artifacts

Answer 16

Violation of assumptions
Equipment malfunction or poor design
The physics of ultrasound
Operator error

Question 17

Six assumptions of Imaging systems

Answer 17

Sound travels in a straight line
Sound travels directly to a reflector and back
Sound travels in soft tissue at exactly 1,540 nm/s
Reflections arise only from structures positioned in the beams main axis
Imaging plane is very thin
Strength of a reflection is related to the characteristics of the tissue creating the reflection

Question 18

Artifacts are seen in what two planes?

Answer 18

Transverse and Sagittal

Question 19

Reverberation appear on the display as?

Answer 19

Multiple, equally, spaced echoes

Question 20

When is reverberation are created when?

Answer 20

Sound wave. Bounces back and forth between

Question 21

Characteristics of reverberation

Answer 21

Appear in multiples
Appear equally spaced
Are located parallel to the sound beam main axis
Located at ever- increasing depths

Question 22

Reverberations resemble ?

Answer 22

Ladder or Venetian blind

Question 23

Comet tail is also known as ?

Answer 23

Reverberation and can be ring down artifact

Question 24

Comet tail appears as

Answer 24

Solid hyper echo if line directed downward.

Question 25

Shadowing appears when ?

Answer 25

Shadowing appears when attenuation is higher in the tissue above the shadow

Question 26

What are the characteristics of shadowing ?

Answer 26

Hypo- anechoic
Result of too much ttenuation
Located beneath the structure with abnormally high attenuation
Pr3vents visualization of true anatomy on the scan

Question 27

Shadows may provide valuable diagnostic information that helps to characterize tissue (no card to flip )

Question 28

Shadowing is entirely unrelated to the speed of sound in a medium (no card to flip)

Question 29

What is the other name for edge shadow?

Answer 29

Refraction shadowing

Question 30

Enhancement is the opposite of shadowing (Page 361 HINT)

Question 31

Enhancement artifacts can be clinically useful. It may provide valuable diagnostic information that helps to characterize tissue. (Page 361 HINT)

Question 32

Enhancement artifact is entirely unrelated to the speed at which sound travels in a medium (page 361 HINT)

Question 33

Edge shadowing appears as ?

Answer 33

Edge shadowing appears as a hyperechoic region