Range resolution is best described as the ability to distinguish echoes from two closely spaced depths along the same beam.

• A. It measures lateral resolution
• B. Distinguishes echoes from two closely spaced depths along the beam
• C. It describes axial resolution
• D. It indicates frame rate

Answer: (B)

Range resolution is the ability to separate echoes that come from objects located at different depths along the ultrasound beam. That’s exactly what the statement describes: distinguishing echoes from two closely spaced depths along the same beam, which is the essence of axial (range) resolution. Shorter spatial pulse length and higher frequency improve this type of resolution because they shorten the distance over which the pulse remains a single, indistinct echo, allowing two close reflectors to be resolved as separate.

In contrast, lateral resolution concerns distinguishing objects that are side by side across the beam, not along its path, and frame rate talks about how often images are updated per second. These are different aspects of image quality and not what range (axial) resolution measures.