What effect is observed in SNR when the field of view (FOV) is increased?

When the field of view (FOV) is increased, the signal-to-noise ratio (SNR) typically increases. This happens because a larger FOV encompasses a larger volume of tissue, which results in collecting more signal from the region being imaged. The additional signal contributes to a higher SNR, as SNR is calculated by comparing the strength of the desired signal to the level of background noise.

The fundamental relationship here involves the fact that as the volume being imaged increases, the contributions of noise (which can be considered relatively constant across the FOV) are averaged out over a larger area. Thus, while the noise level remains similar, the increased signal strength from a broader area enhances the overall SNR.

In terms of imaging practice, increasing the FOV might be necessary to include more anatomical structures, which in turn improves the quality of the image produced. This principle is essential for ensuring that images produced for diagnosis are clearer and contain less relative interference from noise.