Which phenomenon results in increased brightness below a cyst or fluid-filled structure due to reduced attenuation?

• A. Edge Effect
• B. Through Transmission Enhancement
• C. Anisotropy
• D. Acoustic Shadowing

Answer: (B)

Posterior acoustic enhancement is the idea here. Fluid-filled structures attenuate less than surrounding tissue, so the ultrasound beam loses less energy as it passes through the cyst. More sound energy reaches deeper tissues beyond the cyst and the returning echoes are stronger, making the area below the cyst appear brighter on the image. This helps distinguish cystic from solid lesions, since solid areas don’t produce this same enhancement. Edge effects involve bright lines at boundaries, anisotropy is about angle-dependent brightness, and shadowing is a dark region behind an object that heavily attenuates sound.