Speed displacement artifact
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 that 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 location1. However, objects imaged by portions of the ultrasound beam slowed by tissue the beam traverses, will appear discontinuous and artificially deep. A commonly encountered scenario is speed displacement artifact due to slowing of the ultrasound beam by focal fat.