Which transducer type will best mitigate the volume averaging artifact?

• A. Linear array
• B. Phased array
• C. Mechanical 3D
• D. 1.5D or multi-row array

Answer: (D)

Volume averaging occurs when tissue signals within a single imaging voxel from different depths or small structures get averaged together, hiding fine details and blurring edges. The fix is better elevational (slice) resolution, so the beam is focused more narrowly in the direction perpendicular to the image plane. Using a transducer with enhanced elevational control—such as a 1.5D or multi-row array—provides electronic focusing across multiple rows of elements, producing thinner slices and sharper separation of structures in the elevational direction. This directly reduces the volume averaging that blurs small features.

In contrast, a linear or phased array mainly optimize in-plane resolution and steering but have more limited elevational control, so their slice thickness isn’t as thin. Mechanical 3D transducers can sweep volumes, but their elevational resolution is typically constrained by the physical aperture and slice thickness, leading to more pronounced volume averaging than the multi-row approach. Therefore, the 1.5D or multi-row array best mitigates the artifact by delivering finer elevational resolution.