A method in which the sound beam is steered in multiple directions by employing time delays.

• A. Persistence
• B. Panoramic imaging
• C. Time gain compensation
• D. Spatial compounding

Answer: (D)

Beam steering by time delays across the transducer elements is the key idea. In a phased-array probe, applying specific time delays to each element tilts the emitted beam so it travels in a chosen direction. Spatial compounding uses this by steering the beam to multiple angles for separate acquisitions, then combining those views into one image. This multi-angle data gathering helps cancel out speckle and artifacts, and it enhances edge definition and contrast because true structures appear consistently across angles while random noise and angle-specific artifacts are averaged out. The other options don’t describe steering the beam through several directions: persistence is temporal frame averaging for noise reduction, panoramic imaging expands the field of view by stitching images, and time gain compensation adjusts brightness with depth rather than changing the imaging angles.