User's Manual

Vave Personal Ultrasound • USER MANUAL
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6.8.2 Acoustic Artifacts
Image artifacts are common in clinical sonography (ultrasound) and may be a source of confusion. Some artifacts
may be avoidable, caused by improper scanning techniques. Other artifacts are generated by physical limitations.
Ultrasound artifacts can be understood by considering the physical properties of the ultrasound beam, the
propagation of sound in matter, and assumptions of image processing.
Recognition of these artifacts is important because they may indicate tissue composition and inform a diagnosis.
The ability to recognize and remedy ultrasound artifacts is critical for producing quality images and providing
optimal patient care (M.K. Feldman MD et al, 2009).
Acoustic Shadowing is characterized by a signal void behind structures that strongly absorb or reflect
ultrasound waves.
Acoustic Enhancement also called posterior enhancement or enhanced through transmission. Refers to the
increased echoes deep to structures that transmit sound exceptionally well, such as a fluid filled cyst.
Beam Width Artifact occurs when a reflective object located beyond the widened ultrasound beam, after the focal
zone, creates false detectable echoes that are displayed as overlapping the structure of interest. It is possible to
avoid this artifact by adjusting the focal zone to the depth level of interest and by placing the transducer at the
center of the object being studied.
Comet-Tail Artifact is a grey-scale ultrasound finding seen when small calcific/crystalline/highly reflective objects
are interrogated and is believed to be a special form of reverberation artifact.
Mirror Image Artifact is a type of beam path artifact when the interrogating ultrasound beam hits an angled, highly
reflective surface, such as soft tissue/gas interface. It is reflected o into surrounding soft tissue (angle of incidence =
angle of reflection).
Reverberation Artifact occurs when an ultrasound beam encounters two, strong parallel reflectors. When the
ultrasound beam reflects back and forth between the reflectors (“reverberates”), the ultrasound transducer interprets
the sound waves returning from the reverberation as deeper structures, since it took longer for the wave to return to
the transducer. Reverberation artifacts can be improved by changing the angle of insonation so that reverberation
between strong parallel reflectors cannot occur.
Ring Down Artifact is a special type of resonance artifact. Its appearance is similar to the ladder-like reverberation
of comet-tail artifacts, but it is produced by a completely dierent mechanism (gas bubbles).
Refraction Artifact can occur when a transmitted ultrasound pulse strikes an interface at a non-perpendicular angle.
The dierence in propagation speeds between the two tissues can cause refraction to occur. Should the refracted
incident sound wave strike a reflector and cause an echo to return to the transducer, this may be displayed at an
incorrect location as the transducer assumes all echoes have traveled along a direct path. Refraction artifact should
resolve if the transducer is moved such that the incident pulse if perpendicular to the interface.
Speckle Artifact is caused by the scattering of waves from the surface of small structures within a certain tissue and
produces a textured appearance.
Speed Displacement Artifact is a gray scale ultrasound finding that can be identified as an area of focal
discontinuity and displacement of an echo deeper than its actual position in an imaged structure. The artifact is
due to the image processor’s assumption that the velocity of the ultrasound beam within the imaged anatomy is
uniform and that distance of the structure from the transducer is the sole factor determining that structure’s location.
A commonly encountered scenario is a speed displacement artifact due to slowing of the ultrasound beam by local
fat.
Side Lobe Artifacts occur where side lobes reflect sound from a strong reflector that is outside of the central beam.
The echoes display as if they originated from within the central beam. Side lobe artifacts are echogenic, linear or
curvilinear artifacts. Strong reflectors include bowel gas adjacent to the gallbladder or urinary bladder.
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