The SNR is affected by such factors as the volume of the voxel, the bandwidth, and the number of signal averages (NSA).
What affects the signal-to-noise ratio?
The SNR, which is proportional to the square root of the NEX, improves as the NEX increases, but scan time also increases linearly with the NEX. Other parameters affecting the SNR are the sequence used, echo time (TE), repetition time (TR), and the flip angle.
What would increase SNR?
Increasing the FOV will increase the SNR. Increasing the FOV will increase the pixel size which will increase the amount of signals received by individual pixels. Large pixels will receive more signal and produce high SNR images. Increasing the FOV will however reduce the spatial resolution and produce blurry images.