Which term describes the grainy appearance on a sonogram caused by interference of multiple echoes?

• A. Reflection angle
• B. Refraction
• C. Speckle
• D. Specular reflections

Answer: (C)

Speckle is the grainy texture you see on ultrasound images, caused by interference of echoes from many tiny scatterers within the ultrasound beam. When the pulse encounters numerous microstructures in tissue, the echoes return with different phases and amplitudes that combine coherently. The resulting constructive and destructive interference produces bright and dark spots, giving a granular or speckled appearance. This graininess isn’t about a single strong reflection or refraction at a boundary; it’s a property of how many scatterers within each resolution cell interact and how the imaging system sums those echoes. Specular reflections come from smooth surfaces and appear as distinct, strong echoes, not a general speckle pattern, and refraction is the bending of the wave at interfaces. Speckle can be reduced with averaging or advanced beamforming, but at the cost of spatial resolution.