Which of the following contributes to improve the elevation resolution in a B-mode image?

• A. Increased bandwidth
• B. Increased transmit power
• C. Focusing with an acoustic lens
• D. Increased dynamic range

Answer: (C)

Elevation resolution depends on how thin the ultrasound beam is in the elevational (out-of-plane) direction. When you focus the beam with an acoustic lens, the beam narrows in that elevation dimension, producing a thinner focal region. A thinner beam means the system can distinguish structures that are closer together in elevation, so the image looks sharper in that direction.

Bandwidth mainly affects axial resolution, because shorter pulses (higher bandwidth) separate echoes that arrive at different times along the beam path. Increased transmit power improves signal strength and penetration (SNR), not the beam’s thickness. Increased dynamic range changes how many gray levels you can display, affecting contrast rather than geometric resolution.