MRIQC measures¶
Structural images (sMRI)¶
The IQMs computed are as follows:
Identifier | Reference | Description |
---|---|---|
cnr
|
cnr() |
|
efc
|
Entropy Focus Criterion | |
fber
|
Foreground to Background Energy Ratio | |
fwhm
|
Full-width half maximum smoothness of the voxels averaged across the three coordinate axes, and also for each axis | |
qi1
|
Artifact Detection | |
snr
|
Signal to Noise Ratio | |
bias_*
|
[Tustison2010] | Summary measures of the bias field component estimated by N4ITK |
rpve_*
|
Residual Partial Volumes (rPVEs) of CSF, GM and WM. | |
icvs_*
|
Intracranial volumes (ICVs) of CSF, GM and WM. | |
summary_mean_*
summary_stdv_*
summary_p05_*
summary_p95_*
|
Mean, standard deviation, 5% percentile and 95% percentile of the distribution of background, CSF, GM and WM |
Most of these IQMs are migrated or derivated from [QAP].
Functional images (fMRI)¶
The IQMs computed are as follows:
- efc Entropy Focus Criterion
- fber - Foreground to Background Energy Ratio
- fwhm - Full-width half maximum smoothness of the voxels averaged across the three coordinate axes, and also for each axis [x,y,x]
- ghost_x - Ghost to Signal Ratio
- snr - Signal to Noise Ratio
- dvars - Spatial standard deviation of the voxelwise temporal derivates
- gcor - Global Correlation
- mean_fd - Mean Fractional Displacement
- num_fd - Number of volumes with FD greater than 0.2mm
- perc_fd - Percent of volumes with FD greater than 0.2mm
- outlier - Mean fraction of outliers per fMRI volume
- quality - Median Distance Index
- summary_{mean, stdv, p05, p95}_* - Mean, standard deviation, 5% percentile and 95% percentile of the distribution of background and foreground.
References¶
[Tustison2010] Tustison NJ et al., N4ITK: improved N3 bias correction, IEEE Trans Med Imag, 29(6):1310-20, 2010. doi:10.1109/TMI.2010.2046908
[QAP] The Quality Assessment Protocols website: Taxonomy of QA Measures.