artifacts

AXIAL RESOLUTION

This is a type of resolution that is affected by SPL. It refers to the ability to accurately image structures that lie parallel to the main axis of the sound beam

LATERAL RESOLUTION

This type of resolution is affected by beam diameter. If the beam is wider than the distance
between the two reflectors that are side by side, it may read them as one

SLICE THICKNESS ARTIFACT

This type of artifact refers to the thickness of the imaging plane. This artifact may fill in small anechoic cystic spaces with echoes. It is also called partial volume artifact

FOCUSING

This improves lateral resolution

REVERBERATION

This type of artifact is a general term used for multiple equally spaced echoes that appear on the image when the sound beam bounces between 2 strong reflectors

COMET TAIL ARTIFACT

This is a type of reverberation artifact that occurs behind a structure that has a very high propagation speed such as surgical clips, metal or bone

RING DOWN ARTIFACT

This is a type of reverberation artifact that occurs posterior to gas bubbles

MIRRORED IMAGE ARTIFACT

This is a reverberation artifact that occurs when the sound beam reflects off a strong reflector and duplicates the structure deeper on the image. It commonly occurs at the diaphragm

SHADOWING

An artifact that appears hypoechoic or anechoic posterior to a strongly attenuating structure:

EDGE SHADOW or SHADOW BY REFRACTION

A special type of shadowing that occurs along the edge of a curved reflector that lies within an area with a different propagation speed

ENHANCEMENT

This artifact lies posterior to a weakly attenuating structure (such as a cystic lesion) and is seen as a hyperechoic region

FOCAL BANDING or FOCAL ENHANCEMENT

This artifact appears on the image as a horizontal hyperechoic region that is the result of the increased intensity at the area of the focal point

CROSSTALK

This artifact refers to a mirrored image in a spectral display. It may be caused by high Doppler gain setting or the incident angle at or near 90 degrees

REFRACTION AND SIDE LOBES

Two types of artifacts that degrade lateral resolution

SPEED ERROR ARTIFACT

What type of artifact would displace structures axially on the image

ANNULAR ARRAYS AND 1 ½ DIMENSIONAL ARRAYS

What type of transducers have the best elevational resolution

DECREASE DEPTH, INCREASE PRF, DECREASE NUMBER OF FOCAL ZONES, DECREASE FOV

What would improve temporal resolution

INCREASE DEPTH, DECREASE PRF, USE MULTIFOCAL ZONES INCREASE FOV

What would slow down the frame rate

HIGH LINE DENSITY

What would improve spatial resolution

REDUCES NOISE, IMPROVES SIGNAL TO NOISE RATIO

What does harmonic imaging do to the image

HARMONICS

What imaging technique would reduce noise

TOO SHALLOW

If the speed of an object is greater than 1.54 mm/us where would the system place the object on the image

PLACES THE STRUCTURE DEEPER ON THE IMAGE

If the speed of an object is less than the average speed of sound in soft tissue, where would the system place the object on the image

SIDE LOBES

What is the term used to describe weaker beams that are off axis from the main beam that are created by a single element transducer:

GRATING LOBES

Lobes that are created by array transducers are called

SUBDICING

in order to reduce grating lobes the element must be split up into smaller elements. THIS IS CALLED

APODIZATION

Varying the voltages (stronger in center and weaker on the outside) to an element to reduce grating lobes is called

STRONGLY ATTENUATING

Shadowing artifact occurs behind what kind of structure:

WEAKLY ATTENUATING

Enhancement occurs posterior to what kind of structure

DOES NOT ALIAS

Name one advantage of using CWD

CWD

What type of transducer does not alias because it has a crystal that sends and one that receives

USE CWD

Increasing the PRF, dropping the baseline would reduce aliasing. What method would you use to eliminate aliasing altogether

DEAD ZONE

The region on the image where information is inaccurate. It is the result of transducer ringing and taking time to switch to the receive mode

STAND OFF PAD

What would you use to move the superficial mass you are imaging out of the dead zone

GALLBLADDER

Name a structure in the abdomen where edge shadow may occur

DIAPHRAGM

Name a region in the body where grayscale mirrored image may occur

RINGDOWN TIME

This term refers to the time it takes for a transducer to stop ringing

ROUND TRIP TRAVEL TIME

This term refers to the 13 microsecond rule

13 us/cm of depth

The ultrasound instrument is calibrated to the average speed of sound in soft tissue. What is the go return time for every cm of depth

FALSE DEBRIS IN AN ECHO FREE AREA

What effect on your image would the section thickness artifact cause

ALIASING

What is the most common artifact encountered in Doppler ultrasound

INCREASE THE PRF

A good way of reducing aliasing is to increase the velocity scale. Another way of stating this is

DECREASE THE SPL

What would improve axial resolution

UNDER SAMPLING OF THE DOPPLER SHIFTS

What causes aliasing

RANGE AMBIGUITY

Using CWD may be a good way to eliminate aliasing, but its primary disadvantage is

CAUSED BY HIGH PRF

In spectral Doppler range ambiguity is caused by

INCREASE WALL FILTER

What would decrease clutter

GHOSTING

What is the term used for noise from tissue motion in color Doppler

TISSUE MOTION

What causes clutter in Doppler

TWINKLING ARTIFACT

In color Doppler, noise caused by scattering is called

ATTENUATION ARTIFACTS (ATTENUATION GROUP)

What types of artifacts are shadowing and enhancement:

NYQUIST LIMIT

The highest Doppler velocity that can be measured without aliasing is called

PRF/2

The mathematical representation of the NYQUIST LIMIT

SPLIT OR CUT IMAGE

What image distortion is created by propagation speed artifacts

THE 3RD DIMENSION PERPENDICULAR TO THE SCAN PLANE

What part of the image is affected by the section thickness artifact:

NOISE

Low frequency echoes that may result from electrical interference

SPECKLE

A type of noise that arises from small amplitude sound waves interfering with each other causing graininess

CLUTTER

A type of noise associated with Doppler

HIGH LINE DENSITY

A way to increase spatial resolution

TEMPORAL RESOLUTION

The resolution that can accurately follow a moving structure such as RBCs

ANISOTROPY

The name of the artifact that is often seen while scanning the rotator cuff. It appears as a darkened area at the region that is not perpendicular to the sound beam

REFRACTION

may cause duplication of structure, lateral spreading, and poor lateral resolution.
Bending of the transmitted beam caused by different propagation speeds and oblique incident angle.

SPL/2

formula for axial resolution

TWINKLING ARTIFACT

Color fill in of a shadow