Table 4.

Description of selected quality control metrics for T1- and T2-weighted images from MRIQC and selected metrics for diffusion-weighted images from FSL eddy.

Image Type	Metric	Description
T1-, T2-, and Diffusion-weighted	Signal-to-noise ratio (snr)	A measurement of quality of signal within the brain tissue. Higher values are better.
T1- and Diffusion-weighted	Contrast-to-noise ratio (cnr)	A measurement of noise indicating separation of grey and white matter tissue distributions. Higher values are better.
T1- and T2-weighted	Entropy-focus criterion (efc)	A measurement of ghosting and blurring caused by head motion. Lower values are better.
T1-weighted	Coefficient of joint variation (cjv)	A measurement of noise indicating head motion and intensity non-uniformity (INU) artifacts. Lower values are better.
T2-weighted	Mean framewise displacement (fd_mean)	A measurement of head movement across data acquisition calculated by realignment. Lower values are better.
T2-weighted	Median temporal signal-to-noise ratio (tsnr)	A measurement of quality of signal calculated as median signal over temporal standard deviation. Higher values are better.
Diffusion-weighted	Mean of absolute RMS movement (rms_abs)	A measurement of total movement in each volume as compared to the reference volume. Lower values are better.
Diffusion-weighted	Percentage of outlier slices (outlier_pct)	A measurement of data quality calculated as the percentage of outlier slices in a run. Lower values are better.