Which resolution is most directly affected by a wider ultrasound beam?

• A. Axial Resolution
• B. Temporal Resolution
• C. Lateral Resolution
• D. Contrast Resolution

Answer: (C)

Lateral resolution is determined by how wide the ultrasound beam is at a given depth. When the beam is wider, energy from structures that are side by side spreads over a larger area, making it harder to distinguish two objects that are next to each other across the image. In short, a wider beam blurs features laterally, so lateral resolution worsens as beam width increases. Axial resolution depends on how short the pulse is and on wavelength, not on beam width. Temporal resolution relates to frame rate, and contrast resolution depends on signal-to-noise and dynamic range, not the beam’s width.