If you increase the pulse repetition frequency and leave all other controls unchanged, what will happen?

If you increase the pulse repetition frequency and leave all other controls unchanged, what will happen?

• A. Lateral resolution will improve
• B. Frame rate will increase
• C. Frame rate will decrease
• D. Axial resolution will improve

Answer: (B)

Raising the pulse repetition frequency means more ultrasound pulses are emitted each second. If imaging depth and the number of lines per frame stay the same, sending pulses more frequently allows more frames to be formed every second, so the frame rate increases. Lateral resolution depends on beam width and focusing, not on how often pulses are sent, so it stays the same. Axial resolution depends on spatial pulse length (the pulse duration and the number of cycles in the pulse), which is not altered by changing the repetition frequency, so that also remains unchanged. The result is that frame rate goes up.

Raising the pulse repetition frequency means more ultrasound pulses are emitted each second. If imaging depth and the number of lines per frame stay the same, sending pulses more frequently allows more frames to be formed every second, so the frame rate increases. Lateral resolution depends on beam width and focusing, not on how often pulses are sent, so it stays the same. Axial resolution depends on spatial pulse length (the pulse duration and the number of cycles in the pulse), which is not altered by changing the repetition frequency, so that also remains unchanged. The result is that frame rate goes up.