What does BNR stand for in ultrasound?

• A. Baseline neural ratio
• B. Beam nonuniformity ratio
• C. Beam noise ratio
• D. BNR is unrelated to transducer

Answer: (B)

Beam Nonuniformity Ratio describes how uniform the emitted ultrasound beam is. It’s the ratio of the strongest beam intensity to the average intensity across the beam, so a lower value means a more even, consistent image brightness. A beam with low BNR produces clearer, more reliable images with fewer hot spots or dark patches, while a high BNR shows uneven illumination and potential artifacts. This property comes from the transducer’s design and construction, and modern probes aim for a low BNR (more uniform beam).