These B-mode images of the common carotid artery show a graphic overlay indicating the number of lines of sight used to acquire each frame. Which statement is true comparing image A to image B?

• A. Image A has a frame rate higher than image B
• B. Image A has better lateral resolution than image B
• C. Image A has better axial resolution than image B
• D. The temporal resolution is better in image A than in image B

Answer: (B)

Lateral resolution improves when you sample the image from more lines of sight. Collecting data from multiple angles and combining them narrows the effective beamwidth across the width of the image, giving crisper side-to-side detail and better separation of structures along the vessel’s width. If image A uses more lines of sight than image B, it will have better lateral resolution, which is why the statement about A having superior lateral resolution is the true one. Axial resolution depends on pulse length and frequency, not the number of viewing angles, and temporal (frame) rate typically decreases when more lines of sight are used, which is the trade-off you’d expect.