Ch 6 artifact is scanning

Question 1

Axial and lateral resolutions are artifactual because:

a. Echoes originate only from the center of the beam.
b. Ultrasound pulse has a definite length and width in the scan plane.
c. Failure to resolve means a loss of detail.
d. Beam width is parallel to the scan plane.

Answer 1

C

Failure to resolve means a loss of detail, and two adjacent structures may be visualized as one.

Question 2

Multiple reflection can occur between the transducer and a strong reflector. This is an example of:

a. Reverberation
b. Mirror image
c. Speckle tracking

Answer 2

Multiple reflection can occur between the transducer and a strong reflector. This is an example of:

a. Reverberation
b. Mirror image
c. Speckle tracking

Question 3

The artifact that shows structures that exist on one side of a strong reflector as being present on the other side as well is known as:

a. Range ambiguity
b. Mirror image
c. Refraction
d. Speed error

Answer 3

B
Mirror-image artifacts are common around the diaphragm and pleura because of the total reflection from an air-filled lung.

Question 4

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

a. Enhancement
b. Resonance
c. Comet tail
d. Shadowing

Answer 4

D
A strongly attenuating or reflecting structure weakens the sound distal to it, causing echoes from the distal region to be weak and thus to appear dark.

Question 5

The strengthening of echoes from reflectors that lie behind a weak attenuating structure is:

a. Aliasing
b. Multiple reflection
c. Resonance
d. Enhancement

Answer 5

D

Enhancement results in reflectors being placed on the image with amplitudes that are too high.

Question 6

The improper representation of information that has been insufficiently sampled is known as:

a. Multiple reflection
b. Resonance
c. Aliasing
d. Enhancement

Answer 6

: C

Aliasing in its technical use indicates improper representation of information that has been insufficiently sampled

Question 7

The upper limit to the Doppler shift that can be properly detected by pulsed instruments is called:

a. Aliasing
b. Nyquist limit
c. Shadowing
d. Speed error

Answer 7

B
The upper limit to the Doppler shift that can be properly detected by pulsed instruments is called the Nyquist limit. Aliasing occurs when the Doppler shift frequency exceeds one half of the pulse repetition frequency (PRF

Question 8

Artifacts caused by sonographic technique include all of the following except:

a. Noise
b. Banding
c. Side lobes
d. Breathing

Answer 8

C
Side lobes are equipment artifacts caused by secondary (weaker) beams of sound traveling out from a single element in different directions of the primary (main) beam.

Question 9

The best example of a mirror image artifact is seen with the:

a. Gallbladder and cystic duct
b. Pancreas and duodenum
c. Uterus and fallopian tube
d. Diaphragm and liver

Answer 9

D
Mirror imaging occurs if a structure has a curved surface. Structures that exist on one side of a strong reflector are present on the other side as well.

Question 10

Which one of the following will reduce or eliminate aliasing?

a. Decreasing the Doppler angle
b. Decreasing the transducer frequency
c. Increasing the depth of the sample volume
d. Decreasing the pulse repetition frequency.

Answer 10

B
Methods of reducing or eliminating aliasing include increasing the pulse repetition frequency, Doppler angle, and depth of the sample volume. Decreasing the transducer frequency is another method.

Question 11

Refraction can cause a reflector that is:

a. Missing
b. Not real
c. Misplaced
d. Of improper brightness

Answer 11

C

Refraction can cause a reflector to be positioned improperly (lateral) on a sonographic display.

Question 12

Which one of the following artifacts results from constructive and destructive interference of the returning echoes?

a. Noise
b. Speckle
c. Speed error
d. Range ambiguity

Answer 12

: B
Speckle is the interference pattern resulting from constructive and destructive interference of echoes returning simultaneously from many scatterers within the propagating ultrasound pulse at any instant.

Question 13

Echoes resulting from grating lobes may be imaged if they fall within a(n) _________ region.

a. Complex
b. Anechoic
c. Echogenic
d. Hypoechoic

Answer 13

B
If grating lobes encounter a strong reflector (e.g., air), their echoes may well be imaged, particularly if they fall within an anechoic region.

Question 14

Which one of the following structures is most likely to demonstrate strong posterior shadowing?

a. Cyst
b. Air
c. Bone
d. Blood vessel

Answer 14

C
Calcified plaque, bone, and stones are examples of structures that demonstrate strong posterior shadowing. Air demonstrates a “dirty” shadow posteriorly.

Question 15

Increased intensity in the focal region of the sound beam is called focal ___________________.

a. Zones
b. Intensity
c. Banding
d. Intensity

Answer 15

C

Increased intensity in the focal region of the sound beam is called focal banding or focal enhancement

Question 16

. Shadowing is reduced with using:

a. Harmonics imaging
b. Pixel interpolation
c. Three-dimensional imaging
d. Spatial compounding

Answer 16

D
Shadowing is reduced with spatial compounding because several approaches to each anatomic site are used, allowing the beam to “get under” the attenuating structure.

Question 17

Which artifact is most commonly encountered in Doppler ultrasound?

a. Noise
b. Aliasing
c. Mirror image
d. Range ambiguity

Answer 17

B

Aliasing is the most common artifact encountered in Doppler ultrasound.

Question 18

Which one of the following eliminates aliasing using the “cut and paste” technique?

a. Shifting the baseline
b. Decreasing the Doppler angle
c. Increasing the transducer frequency
d. Increasing the pulse repetition frequency

Answer 18

A
Baseline shift is an electronic “cut and paste” technique that moves the misplaced aliasing peaks over their proper location.

Question 19

. Which of the following solutions are common and convenient to aliasing?

a. Shifting the baseline and decreasing the pulse repetition frequency
b. Decreasing the pulse repetition frequency and increasing the depth of the sample gate
c. Shifting the baseline and increasing the pulse repetition frequency
d. Increasing the pulse repetition frequency and decreasing the depth of the sample gate

Answer 19

C

Shifting the baseline and increasing the pulse repetition frequency are common and convenient solutions to aliasing.

Question 20

To decrease internally generated electronic noise in the Doppler signal, the sonographer should decrease the:

a. Doppler gain
b. Overall gain
c. Imaging depth
d. Transducer frequency

Answer 20

A

Internally generated electronic noise appears if the Doppler gain is set too high.

Question 21

Reverberation artifact displays structures that are:

a. Not real
b. Misplaced
c. Improper in shape
d. Improper in brightness

Answer 21

A

Reverberation (multiple reflections) results in the display of additional reflectors that are not real.

Question 22

Increasing the pulse repetition frequency increases the chances of displaying which one of the following artifacts?

a. Speckle
b. Aliasing
c. Mirror image
d. Range ambiguity

Answer 22

D
Higher pulse repetition frequencies (PRF) permit higher Doppler shifts to be detected but also increase the chance of the range ambiguity artifact occurring.

Question 23

Cross-talk can produce which one of the following artifacts?

a. Noise
b. Aliasing
c. Mirror image

Answer 23

C

Cross-talk can produce a Doppler mirror image artifact

Question 24

Refraction of the sound beam at a boundary may result in false sonographic ________________.

a. Brightness
b. Duplication
c. Shadowing
d. Enhancement

Answer 24

C

Refraction of the sound beam at a boundary may result in false sonographic shadowing (edge shadowing).

Question 25

The width of the pulse determines ______________ resolution.

a. Temporal
b. Lateral
c. Axial
d. Contrast

Answer 25

B

The width of the pulse determines lateral resolution