Which ultrasound artifact is described as an edge shadow?

• A. Edge shadow
• B. Acoustic enhancement
• C. Posterior shadowing
• D. Ringing

Answer: (A)

Edge shadowing is the shadow artifact that appears along the edge of a curved or rounded structure. It happens because the ultrasound beam interacts with the curved boundary in a way that reduces echo returns at and just beyond the edge, so you see a darker line tracing the rim of the lesion. This differs from posterior shadowing, which lies behind the structure due to attenuation, and from acoustic enhancement, which brightens the area behind a fluid-filled lesion, and from ringing, which shows as multiple parallel reverberations. Edge shadowing is characteristic of the edge of a curved interface, such as the rim of a cyst or rounded mass.