Which setting should you lower to improve sensitivity to slow flow?

Which setting should you lower to improve sensitivity to slow flow?

• A. Lower the packet size
• B. Lower the transmitted Doppler frequency
• C. Lower wall filter setting
• D. Raise the PRF

Answer: (C)

Sensitivity to slow flow comes from letting low-frequency Doppler signals pass through to the display. The wall filter acts as a high-pass filter on Doppler data, removing the slow components associated with tissue motion. Lowering the wall filter reduces this high-pass effect, so the slower Doppler shifts from slow-flowing blood become visible. This is why reducing the wall filter is the best way to improve sensitivity to slow flow. Just be aware that going too low can bring in clutter from tissue motion, so it’s a matter of balancing visibility with noise. Other options don’t target slow-flow detection in the same way. Packet size affects data transmission rather than velocity information. Lowering the transmitted Doppler frequency reduces the Doppler shift magnitude, making slow flow even harder to detect. Raising the PRF changes the velocity range and aliasing characteristics but doesn’t specifically enhance visibility of slow-flow signals.

Sensitivity to slow flow comes from letting low-frequency Doppler signals pass through to the display. The wall filter acts as a high-pass filter on Doppler data, removing the slow components associated with tissue motion. Lowering the wall filter reduces this high-pass effect, so the slower Doppler shifts from slow-flowing blood become visible. This is why reducing the wall filter is the best way to improve sensitivity to slow flow. Just be aware that going too low can bring in clutter from tissue motion, so it’s a matter of balancing visibility with noise.

Other options don’t target slow-flow detection in the same way. Packet size affects data transmission rather than velocity information. Lowering the transmitted Doppler frequency reduces the Doppler shift magnitude, making slow flow even harder to detect. Raising the PRF changes the velocity range and aliasing characteristics but doesn’t specifically enhance visibility of slow-flow signals.