The ratio of meaningful signal to noise in an ultrasound image is:

• A. Signal to Noise Ratio
• B. Spatial Compounding
• C. Specular
• D. A-Mode

Answer: (A)

At its heart, this ratio measures how much of what you see in the image comes from true tissue echoes versus random background variation. In ultrasound, the meaningful signal comes from interfaces that reflect sound, while noise comes from electronic noise, artifacts, and speckle. A higher signal-to-noise ratio means the tissue information stands out clearly, producing a crisper image and making it easier to resolve structures. A lower ratio results in a grainier image where small details may be obscured.

Spatial compounding is a technique used to improve image quality by combining information from different angles, which can reduce speckle and enhance visibility. Specular describes a mirror-like reflection direction, not a ratio. A-Mode is a one-dimensional depth display, not a measure of signal quality.