Caused by a lower attenuation within the structure than in the surrounding tissue.

Caused by a lower attenuation within the structure than in the surrounding tissue.

• A. Enhancement
• B. Shadowing
• C. Refraction
• D. Diffraction

Answer: (A)

Enhancement occurs when a structure attenuates less than the surrounding tissue, allowing more ultrasound energy to pass through and reach deeper tissues. The result is stronger echoes and a brighter area behind the structure, known as posterior acoustic enhancement—typical of fluid-filled or cystic areas. Shadowing, by contrast, happens with highly attenuating structures and produces a dark region beyond them. Refraction and diffraction describe bending of waves at interfaces or around edges, not this posterior brightening.

Enhancement occurs when a structure attenuates less than the surrounding tissue, allowing more ultrasound energy to pass through and reach deeper tissues. The result is stronger echoes and a brighter area behind the structure, known as posterior acoustic enhancement—typical of fluid-filled or cystic areas. Shadowing, by contrast, happens with highly attenuating structures and produces a dark region beyond them. Refraction and diffraction describe bending of waves at interfaces or around edges, not this posterior brightening.