compute_framewise_displacement

bidsaid.qc.compute_framewise_displacement(input_data, has_header=True, rotation_units='radians', radius=50, verbose=False)[source]

Computes the framewise displacement using the Power (2012) formula:

FDi=|Δxi|+|Δyi|+|Δzi|+|Δαi|+|Δβi|+|Δγi|

  • where i is the timepoint/volume

  • x, y and z are the three translation parameters

  • α, β and γ are the three rotational parameters

  • Δxi=xi−1−xi

Parameters

input_datastr, Path, pandas.DataFrame, or NDArray

Input data containing values to threshold. Can be a path to a text file (where delimiter is whitespace, tabs, or commas), a DataFrame.

Important

  • If has_header is False, then the first six columns will be assumed to be the three translations and three rotations.

  • Assumes first three columns are translation parameters in mm and last three columns are rotation parameters in radians or degrees.

has_headerbool, default=True

Whether the input file has a header row. Only used when input_data is a file path.

rotation_unitsLiteral["radians", "degrees"], default=”radians”

The units of the rotation parameters.

radiusint or float, default=50

The radius of the head in mm.

verbosebool, default=False

Logs “INFO” level information if True.

Returns

NDArray

A numpy array of the computed framewise displacements. Note that the first value will always be 0.

References

Power, J. D., Barnes, K. A., Snyder, A. Z., Schlaggar, B. L., & Petersen, S. E. (2012). Spurious but systematic correlations in functional connectivity MRI networks arise from subject motion. NeuroImage, 59(3), 2142–2154. https://doi.org/10.1016/j.neuroimage.2011.10.018

Mejia, A., Muschelli, J., & Pham, D. fMRIscrub: fMRI scrubbing (R package). https://neuroconductor.org/help/fMRIscrub/reference/FD.html