Which disadvantage is associated with a tightly curved array as depth increases?

• A. Axial resolution degrades with depth
• B. Field of view is compromised
• C. Temporal resolution is compromised
• D. Lateral resolution degrades with depth

Answer: (D)

Lateral resolution is determined by how narrow the ultrasound beam is at a given depth. A tightly curved (curvilinear) array focuses the beam to achieve the best lateral detail near its focal zone. As depth increases away from that focus, diffraction causes the beam to widen. A broader beam can’t distinguish two closely spaced objects as well, so the ability to separate signals side by side deteriorates with depth. That’s why depth-related degradation is seen in lateral, rather than axial, resolution for a curved array.

Axial resolution, set by pulse length and frequency, stays essentially constant with depth (though signal strength and noise do change). Field of view and temporal resolution depend on other factors like transducer geometry and scan strategy, not primarily on depth in the same way lateral focusing does.