What type of artifact can result from refraction?

Refraction artifacts occur when sound waves bend as they pass through different tissues at an interface, which can cause structures to appear displaced from their actual locations. The phenomenon of double images arises from this bending, giving the impression that a single object is represented in two different locations on the ultrasound image. This occurs because the ultrasound beam travels at varying speeds in tissues of different densities, causing the misplacement of echoes that are reflected back to the transducer, thereby presenting two seemingly separate images of the same structure.

In contrast, acoustic shadowing, reverberation, and edge enhancement represent different kinds of artifacts that do not stem from the bending of sound waves. Acoustic shadowing is the result of sound waves being absorbed or reflected by dense structures, which prevents echoes from reaching the transducer. Reverberation occurs when sound waves bounce back and forth between reflectors, creating multiple echoes. Edge enhancement refers to a technique used to improve the visibility of structures at the edges but does not relate to sound wave refraction. Hence, the correct choice reflecting the outcome of refraction is the double image.