Which term describes the thickness of the scanned tissue perpendicular to the scan plane, determined by the transducer?

• A. Slice thickness
• B. Lateral resolution
• C. Frame rate
• D. Temporal resolution

Answer: (A)

Slice thickness is the dimension of the imaging volume that lies perpendicular to the scan plane. It is determined by the transducer’s elevational beam pattern and focusing, so the echoes come from a finite thickness of tissue, not just a single plane. This can lead to partial-volume effects when small structures are partly within that thickness, affecting image accuracy.

Lateral resolution is about distinguishing structures side to side within the scan plane, dependent on beam width in the plane. Frame rate and temporal resolution relate to how many frames are acquired per second and how well motion is resolved over time, respectively, and are influenced by depth and line density, not the out-of-plane thickness.