Which imaging artifact is much worse on the left phantom image compared to the right phantom image?

• A. Reverberation
• B. Range ambiguity
• C. Volume averaging
• D. Multipath

Answer: (C)

Volume averaging is the imaging artifact at play here. It happens when the ultrasound system uses a thicker elevational (slice) thickness, so echoes from multiple structures at slightly different depths within the imaging plane are averaged together into one image pixel. That averaging blurs edges and reduces contrast, making features look smeared or less distinct.

If the left phantom was scanned with a thicker slice, more structures within that plane contribute to each pixel, producing the noticeable blur and loss of detail you see there. The right phantom, with a thinner slice, limits accumulation to a narrower depth range, so its features appear crisper and less averaged.

Reverberation, range ambiguity, and multipath produce different patterns (repeating lines, depth misplacements, or echoes from multiple paths) that don’t explain the pronounced left–right difference tied to slice thickness in the same way volume averaging does.