Artifacts In Ultrasound

Slice Thickness Artifact

When height dimensions of a sound beam is thicker than the interface between two adjacent structures. It has a loss of lateral and axial resolution

Speckle

Combination of constructive and destructive interference of sound waves. New equipment can reduce this

Reverberation

The bouncing of sound waves between two strong interfaces. Has linear echoes

Mirror image

Caused by sound waves interacting with a large curved reflector (diaphragm)

Comet tail

Large difference between acoustic impedance and the reflector and surrounding tissue. Cause a series of short path reverberations. Small bands seen distal to reflector. Very echogenic bands

Resonance (ring down)

Occurs when sound strikes a gas bubble causing a vibration. No banding is seen. Distinguishes this from comet-tail

Refraction-misregistration

Distorted due to refraction of sound beam. Snell’s law

Refraction-defocusing

Narrow shadowing that extends off of a curved border

Ghost image refraction

Cause by scanning through the abdominal muscles. There are duplications of structures posterior to the abdominal muscles

Side lobes

Echoes from off-axis, low intensity side beam are incorrectly interpreted as coming from main central beam. Causes structures located outside the field of view to be displayed inside the field of view. Arise from a sound beam of individual elements

Grating lobes

Greater intensity than side lobes. Cumulative effect of multiple elements. Created by how elements are spaced in an array transducer

Propagation speed error

If it travels faster than assumed object is displayed more superficial

Propagation speed error

If the object is slower than assumed it will be seen deeper

range ambiguity artifact

Echoes are not received by transducer until after next pulse is transmitted. To fix decrease your PRF (maximum depth)

Sound tissue artifact (dirty shadow)

When sound beam hits a spot of bowel gas or air (shows snow grey shadow)

sharp shadow

When a sound waves hit a calcified object. Produces a black area posterior to the object.

Posterior enhancement

Poorly attenuating structures cause this

Noise

Gain is too high and causes this

Banding

A row in the image is too dark. This is from the TGCs not being properly placed

Motion artifact

This is caused by breathing