I am trying to see how "good" our signal is by computing the Signal-to-Noise ratio (SNR), but so far I have only read from a book on DSP that SNR is defined only as the mean divided by the standard deviation of the signal. Also the book defines Coefficient of variation (CV) as the standard deviation divided by the mean, multiplied by 100.
Computing the Signal-to-Noise-Ratio (SNR) of DW images is still an open question, as SNR depends on the white matter structure of interest as well as the gradient direction corresponding to each DWI. In classical MRI, SNR can be defined as the ratio of the mean of the signal divided by the standard deviation of the underlying Gaussian noise ...