You are observing a sonographic artifact based on the interference patterns of scattered echoes. What artifact are you imaging?

• A. Mirror
• B. Grating lobes
• C. Acoustic speckle
• D. Refraction

Answer: (C)

Acoustic speckle comes from interference of echoes scattered by many small structures within the tissue. As those scattered waves combine, they create a granular, grainy texture on the image that is not a real object but a pattern produced by constructive and destructive interference. This speckle pattern is influenced by scan angle and frequency and can be reduced with techniques like spatial compounding, though some clinical value can remain in texture analysis. Other artifacts arise from different physical causes—mirror artifacts are ghost images from strong reflectors, grating lobes are off-axis echoes from array design, and refraction is the bending of waves at boundaries with different speeds—so the characteristic speckled appearance specifically points to acoustic speckle.