Chapter 7 Artifacts

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

a. noise.

b. banding.

c. side lobes.

d. breathing.

c. side lobes.

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

a. brightness

b. duplication

c. shadowing

d. enhancement

c. shadowing

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

a. Shifting the baseline

Shadowing is reduced by using:

a. harmonics imaging.

b. pixel interpolation.

c. three-dimensional imaging.

d. spatial compounding.

d. spatial compounding.

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

a. complex

b. anechoic

c. echogenic

d. hypoechoic

b. anechoic

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.

b. mirror image.

Reverberation artifact displays structures that are:

a. not real.

b. misplaced.

c. improper in shape.

d. improper in brightness.

a. not real.

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

a. reverberation.

b. mirror image.

c. speckle tracking.

d. refraction.

a. reverberation.

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

b. Speckle

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

d. Range ambiguity

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

a. Noise

b. Aliasing

c. Mirror image

d. Range ambiguity

c. Mirror image

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.

a. Doppler gain.

Identify the artifact commonly seen with pulsed wave Doppler imaging.

a. Noise

b. Aliasing

c. Mirror image

d. Range ambiguity

b. Aliasing

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

a. Cyst

b. Air

c. Bone

d. Blood vessel

c. Bone

Insufficient sampling during a Doppler study that results in the improper representation of information is known as:

a. multiple reflection.

b. resonance.

c. aliasing.

d. enhancement.

c. aliasing.

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.

d. shadowing.

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.

d. diaphragm and liver.

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 increasing the depth of the sample gate

c. Shifting the baseline and increasing the pulse repetition frequency

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

b. Decreasing the transducer frequency

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

a. zones

b. intensity

c. banding

d. attenuation

c. banding

The width of the pulse determines ______________ resolution.

a. temporal

b. lateral

c. axial

d. contrast

b. lateral

Refraction can cause a reflector that is:

a. missing.

b. not real.

c. misplaced.

d. of improper brightness.

c. misplaced.

Lack of axial and lateral resolution result in:

a. echoes originating only from the center of the beam.

b. decrease in ultrasound pulse length and width in the scan plane.

c. Failure to resolve structures and detail loss.

d. beam width artifacts on the scan plane.

c. Failure to resolve structures and detail loss.

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

a. aliasing.

b. Nyquist limit.

c. shadowing.

d. speed error.

b. Nyquist limit.

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

a. aliasing.

b. multiple reflection.

c. resonance.

d. enhancement.

d. enhancement.