Two forms of reflection created in soft tissue are which?

• A. Specular and Diffuse
• B. Specular and Diffuse-like
• C. Specular and Backscatter
• D. Diffuse and Backscatter

Answer: (A)

The concept tested is how ultrasound energy reflects off tissue interfaces. There are two main forms: specular reflection and diffuse reflection. Specular reflection behaves like a mirror—when the interface is smooth relative to the wavelength, the sound reflects in a single direction, producing a strong echo only if the angle is favorable. Diffuse reflection occurs at rough, irregular interfaces, scattering energy in many directions; most of this scattered energy returns to the transducer as backscatter, which contributes to the speckled brightness seen in soft-tissue images. In soft tissue, a multitude of microstructures cause diffuse reflections, while smoother boundaries create specular echoes. The other options mix nonstandard terminology or treat backscatter as a separate form, but backscatter is best understood as a type of diffuse reflection.