Artifacts in Ultrasound

With various causes, artifacts are nearly constant, both in B-mode and in Doppler. These phenomena of artificial origin are readily recognizable, although sometimes difficult to detect. Knowing how to recognize them is important to avoid diagnostic errors. They can sometimes be a diagnostic help, but more often it is useful to know how to minimize them. We first review the artifacts in B-mode. The different artifacts are classified, described and illustrated according to whether they are related to (1) the physics of ultrasound and acoustics: reverberation echoes, comet tail/dirty shadowing, mirror image, posterior (acoustic) enhancement, acoustic shadowing, edge shadow (oblique reflection, refraction), velocity artifacts (Baum bump), scattering artifacts - dispersion (speckle); (2) the ultrasound technique and sensors: side-lobe artifacts and partial volume artifacts; (3) ultrasound and sensor malfunctions and environmental artifacts; and (4) complex artifacts (intraocular gas). Then artifacts encountered in Doppler are studied, in relation to unsuitable velocity scale settings (absence of flow if pulse repetition frequency is too high, aliasing if pulse repetition frequency is too low), spectrum broadening (turbulence), and color coding outside of vessels (perivascular blooming artifact, twinkling artifact, and artifacts related to movements).