fmri_snri

Description

FMRI_SNRI Image-domain signal-to-noise ratio (SNR-i) for each fMRI scan. Computes the image SNR for each time point as the ratio of the mean signal across all brain voxels to its standard deviation: SNR-i = mean(S_t) / std(S_t) A high SNR-i indicates that signal variation across voxels within a scan is small relative to the mean, suggesting low inter-voxel noise.

Usage

SNR = fmri_snri(v)

Inputs

V: fMRI data, vectorized (228453 x T) or volume (91 x 109 x 91 x T).

Outputs

SNR: Image SNR per time point (T x 1).

Examples

snr = fmri_snri(data);
plot(snr); xlabel('Scan'); ylabel('SNR-i')