I would like to calculate the SNR by dividing the mean intensity of the signal of interest by the SD of the noise. To do this, I would like to create a small circular ROI and place it within the region of interest and a larger circular ROI and place it within the 'background' region that is parcelled to each subject in apas+head.mgz (ID=130).
Do you know what functions I can use to create these ROIs and place them within the regions I want?
Do you know a better method to calculate the SNR?
Thank you in advance.
Best regards,
Marina