The grainy image texture due to interference of scattered waves is called:

• A. Shading
• B. Speckle
• C. Reverberation
• D. Shadow

Answer: (B)

Speckle is the grainy texture you see in ultrasound images, caused by the interference of echoes from many tiny scatterers inside the tissue. Each microstructure reflects sound in different directions, and when those echoes return to the transducer their waves combine with varying phases. Some spots become brighter through constructive interference, others darker through destructive interference, creating a random, grainy pattern. This speckle is inherent to coherent imaging and can blur fine detail, though it also contains information about tissue texture that can be used in specialized analyses. Other artifacts have different causes—shading refers to gradual brightness changes from beam profile and attenuation, reverberation comes from multiple reflections producing repeated bands, and shadow is a dark region behind an opaque or highly attenuating object.