When you increase the scan line density in the B- mode image, you improve:

• A. A temporal resolution
• B. B contrast resolution
• C. C slice thickness
• D. D lateral resolution

Answer: (D)

Increasing scan line density means you sample the image across the width more finely. That finer lateral sampling lets two structures that are side by side be represented by more separate data points, so closely spaced echoes can be distinguished more clearly in the lateral direction. In other words, lateral resolution improves because you have more samples across the width to resolve side-by-side features.

But there’s a trade-off: adding more scan lines takes more time to acquire each frame, so the frame rate drops and temporal resolution worsens. Also, axial resolution, slice thickness, and contrast resolution aren’t directly improved by changing line density—they depend more on pulse length and bandwidth, beam geometry, and image processing settings.