Which statement best describes system sensitivity?

• A. Ability to detect weak echoes
• B. Ability to demonstrate highly reflective interfaces
• C. Ability to differentiate small amplitude differences
• D. Ability to resolve two structures parallel to the beam

Answer: (A)

Sensitivity is the system’s ability to pick up weak echoes. This determines whether faint reflections from deeper or less-echoic tissues can be detected above the noise floor, which is crucial for seeing subtle or distant structures. Factors like the receiver noise level, gain settings, and the overall signal-to-noise ratio shape this capability. The option about detecting weak echoes directly captures this idea. The other statements describe different aspects of image quality: brightness from highly reflective interfaces relates to reflectivity, differentiating small amplitude differences concerns gray-scale or contrast resolution, and resolving structures along the beam pertains to axial (along-beam) resolution rather than sensitivity.