Propagation speed error results in which sonographic appearance?

Propagation speed error results in which sonographic appearance?

• A. Improper lateral position of an echo
• B. Shadowing behind an echo
• C. Enhancement behind an echo
• D. Improper axial position of an echo

Answer: (D)

Propagation speed error changes how time is converted to depth, so the echoes are placed at the wrong axial position. The system assumes a specific speed of sound to translate round-trip time into depth; if the actual speed is different, the calculated depth shifts. If the actual speed is slower than assumed, echoes appear deeper than they really are; if faster, they appear shallower. This causes an improper axial position of echoes. Lateral placement and features like shadowing or enhancement relate to geometry or attenuation, not to propagation speed, so they don’t reflect this timing-based depth error.

Propagation speed error changes how time is converted to depth, so the echoes are placed at the wrong axial position. The system assumes a specific speed of sound to translate round-trip time into depth; if the actual speed is different, the calculated depth shifts. If the actual speed is slower than assumed, echoes appear deeper than they really are; if faster, they appear shallower. This causes an improper axial position of echoes. Lateral placement and features like shadowing or enhancement relate to geometry or attenuation, not to propagation speed, so they don’t reflect this timing-based depth error.