Which factor primarily influences the lateral resolution in ultrasound?

Lateral resolution in ultrasound refers to the ability to distinguish two structures that are positioned side by side at the same depth. This capability is primarily influenced by the beam width of the ultrasound wave.

As the beam width decreases, lateral resolution improves because a narrower beam can more accurately separate closely spaced reflectors laterally. In practical terms, this means that two objects positioned closely together can be identified as distinct entities instead of appearing as a single object.

While other factors like frequency and pulse duration contribute to other aspects of ultrasound imaging quality—frequency primarily affects axial resolution and pulse duration relates to temporal resolution—they do not directly affect lateral resolution in the same way that beam width does. Propagation speed impacts the overall speed of sound through tissues and the timing of image formation, but it does not have a direct role in the resolution of structures side by side.

Understanding how beam width impacts lateral resolution is fundamental for optimizing image quality and ensuring accurate diagnostics in clinical practice.