What term describes the ability to distinguish two structures lying perpendicular to the sound beam?

• A. Lateral resolution
• B. Axial resolution
• C. Temporal resolution
• D. Contrast resolution

Answer: (A)

Lateral resolution describes the ability to distinguish two reflectors that are side-by-side across the ultrasound beam, perpendicular to the beam’s path. This resolution depends on how narrow the beam is in the lateral direction; a tighter beam width (better focusing, higher frequency, and advanced array techniques) makes it possible to separate structures that are close together side-to-side.

By contrast, axial resolution is about separation along the beam path (range direction) and is influenced by pulse length and bandwidth; temporal resolution relates to how quickly frames are acquired (frame rate); and contrast resolution concerns the ability to distinguish different echo intensities. Thus, the term for distinguishing structures perpendicular to the beam is lateral resolution.