Which resolution is defined along the ultrasound beam axis and affects the ability to distinguish two reflectors in that direction?

Which resolution is defined along the ultrasound beam axis and affects the ability to distinguish two reflectors in that direction?

• A. Axial
• B. Lateral
• C. Elevations
• D. Temporal

Answer: (A)

Axial resolution is the ability to distinguish two reflectors that lie along the path of the ultrasound beam. It depends on the spatial pulse length—the physical length of one pulse in tissue. Shorter pulses (higher frequency or fewer cycles) shorten the spatial pulse length and thus improve axial resolution, allowing two closely spaced reflectors to be shown as separate echoes. In practice, two reflectors must be separated by about half a spatial pulse length to be resolved along the beam axis. Lateral resolution, by contrast, concerns separation across the beam and is affected by beam width and focusing. Elevational (slice-thickness) resolution deals with the third dimension, the beam’s thickness in the elevational direction. Temporal resolution relates to how quickly frames are acquired and is about time, not spatial separation.

Axial resolution is the ability to distinguish two reflectors that lie along the path of the ultrasound beam. It depends on the spatial pulse length—the physical length of one pulse in tissue. Shorter pulses (higher frequency or fewer cycles) shorten the spatial pulse length and thus improve axial resolution, allowing two closely spaced reflectors to be shown as separate echoes. In practice, two reflectors must be separated by about half a spatial pulse length to be resolved along the beam axis.

Lateral resolution, by contrast, concerns separation across the beam and is affected by beam width and focusing. Elevational (slice-thickness) resolution deals with the third dimension, the beam’s thickness in the elevational direction. Temporal resolution relates to how quickly frames are acquired and is about time, not spatial separation.