How does changing the receiver bandwidth (rBw) affect SNR according to MRI principles?

• A. Increasing rBw increases SNR
• B. Decreasing rBw increases SNR
• C. rBw does not affect SNR
• D. Changing rBw has unpredictable effects

Answer: (B)

Changing the receiver bandwidth (rBw) has a significant impact on the signal-to-noise ratio (SNR) in magnetic resonance imaging (MRI). When the rBw is decreased, the SNR increases. This occurs because a lower rBw allows for a narrower frequency range to be sampled, thereby reducing the amount of noise collected. Noise in MRI is distributed across a broad frequency spectrum, and by focusing only on a narrower range of frequencies, you can isolate the desired signal from the background noise.

In practical terms, this means that when you reduce the rBw, the system is more selective about which signals it accepts, which enhances the clarity and quality of the images obtained. However, a lower rBw also leads to longer acquisition times, which can complicate patient management and imaging workflows. Therefore, while decreasing the receiver bandwidth increases SNR, it is crucial for MRI technologists to balance this with other imaging parameters to optimize both image quality and patient comfort.