Generate Motion and Power Statistics#

class CPAC.generate_motion_statistics.ImageTo1D(**inputs)[source]#

input_spec#: alias of CPAC.generate_motion_statistics.generate_motion_statistics.ImageTo1DInputSpec

output_spec#: alias of CPAC.generate_motion_statistics.generate_motion_statistics.ImageTo1DOutputSpec

CPAC.generate_motion_statistics.calculate_DVARS(func_brain, mask)[source]#

Method to calculate DVARS as per power’s method

Parameters

func_brain (string (nifti file)) – path to motion correct functional data
mask (string (nifti file)) – path to brain only mask for functional data

Returns

out_file – path to file containing array of DVARS calculation for each voxel

Return type

string (numpy mat file)

CPAC.generate_motion_statistics.calculate_FD_J(in_file, motion_correct_tool='3dvolreg', center=None)[source]#

Method to calculate framewise displacement as per Jenkinson et al. 2002

Parameters

in_file (string) – matrix transformations from volume alignment file path if motion_correct_tool is ‘3dvolreg’, or FDRMS (*_rel.rms) output if motion_correct_tool is ‘mcflirt’.
motion_correct_tool (string) – motion correction tool used, ‘3dvolreg’ or ‘mcflirt’.
center (ndarray) – optional volume center for the calculation.

Returns

out_file – Frame-wise displacement file path

Return type

string

CPAC.generate_motion_statistics.calculate_FD_P(in_file)[source]#

Method to calculate Framewise Displacement (FD) as per Power et al., 2012

Parameters: in_file (string) – movement parameters vector file path
Returns: out_file – Frame-wise displacement mat file path
Return type: string

CPAC.generate_motion_statistics.gen_motion_parameters(subject_id, scan_id, movement_parameters, max_displacement, motion_correct_tool)[source]#

Method to calculate all the movement parameters

Parameters

subject_id (string) – subject name or id
scan_id (string) – scan name or id
max_displacement (string) – path of file with maximum displacement (in mm) for brain voxels in each volume
movement_parameters (string) – path of 1D file containing six movement/motion parameters(3 Translation, 3 Rotations) in different columns (roll pitch yaw dS dL dP)

Returns

out_file – path to csv file containing various motion parameters

Return type

string

CPAC.generate_motion_statistics.gen_power_parameters(subject_id, scan_id, fdp=None, fdj=None, dvars=None, motion_correct_tool='3dvolreg')[source]#

Method to generate Power parameters for scrubbing

Parameters

subject_id (string) – subject name or id
scan_id (string) – scan name or id
FDP_1D (string) – framewise displacement(FD as per power et al., 2012) file path
FDJ_1D (string) – framewise displacement(FD as per jenkinson et al., 2002) file path
threshold (float) – scrubbing threshold set in the configuration by default the value is set to 1.0
DVARS (string) – path to numpy file containing DVARS

Returns

out_file – path to csv file containing all the pow parameters

Return type

string (csv file)

CPAC.generate_motion_statistics.motion_power_statistics(name='motion_stats', motion_correct_tool='3dvolreg')[source]#

The main purpose of this workflow is to get various statistical measures: from the movement/motion parameters obtained in functional preprocessing.

:param : :type : param str name: Name of the workflow, defaults to ‘motion_stats’ :param : :type : return: Nuisance workflow. :param : :type : rtype: nipype.pipeline.engine.Workflow

Notes

Workflow Inputs:

inputspec.subject_id : string
    Subject name or id

inputspec.scan_id : string
    Functional Scan id or name

inputspec.motion_correct : string (func/rest file or a list of func/rest nifti file)
    Path to motion corrected functional data

inputspec.max_displacement : string (Mat file)
    maximum displacement (in mm) vector for brain voxels in each volume.
    This file is obtained in functional preprocessing step

inputspec.movement_parameters : string (Mat file)
    1D file containing six movement/motion parameters(3 Translation, 3 Rotations)
    in different columns (roll pitch yaw dS  dL  dP), obtained in functional preprocessing step

Workflow Outputs:

outputspec.FDP_1D : 1D file
    mean Framewise Displacement (FD)

outputspec.power_params : txt file
    Text file containing various power parameters for scrubbing

outputspec.motion_params : txt file
    Text file containing various movement parameters

Order of commands:

Calculate Framewise Displacement FD as per power et al., 2012

Differentiating head realignment parameters across frames yields a six dimensional timeseries that represents instantaneous head motion. Rotational displacements are converted from degrees to millimeters by calculating displacement on the surface of a sphere of radius 50 mm.[R5]
Calculate Framewise Displacement FD as per jenkinson et al., 2002
Calculate DVARS

DVARS (D temporal derivative of timecourses, VARS referring to RMS variance over voxels) indexes the rate of change of BOLD signal across the entire brain at each frame of data.To calculate DVARS, the volumetric timeseries is differentiated (by backwards differences) and RMS signal change is calculated over the whole brain.DVARS is thus a measure of how much the intensity of a brain image changes in comparison to the previous timepoint (as opposed to the global signal, which is the average value of a brain image at a timepoint).[R5]

Calculate Power parameters:

MeanFD : Mean (across time/frames) of the absolute values for Framewise Displacement (FD),
computed as described in Power et al., Neuroimage, 2012)

rootMeanSquareFD : Root mean square (RMS; across time/frames) of the absolute values for FD

rmsFD : Root mean square (RMS; across time/frames) of the absolute values for FD

FDquartile(top 1/4th FD) : Mean of the top 25% highest FD values

MeanDVARS : Mean of voxel DVARS

Calculate Motion Parameters

Following motion parameters are calculated:

Subject
Scan
Mean Relative RMS Displacement
Max Relative RMS Displacement
Movements > threshold
Mean Relative Mean Rotation
Mean Relative Maxdisp
Max Relative Maxdisp
Max Abs Maxdisp
Max Relative Roll
Max Relative Pitch
Max Relative Yaw
Max Relative dS-I
Max Relative dL-R
Max Relative dP-A
Mean Relative Roll
Mean Relative Pitch
Mean Relative Yaw
Mean Relative dS-I
Mean Relative dL-R
Mean Relative dP-A
Max Abs Roll
Max Abs Pitch
Max Abs Yaw
Max Abs dS-I
Max Abs dL-R
Max Abs dP-A
Mean Abs Roll
Mean Abs Pitch
Mean Abs Yaw
Mean Abs dS-I
Mean Abs dL-R
Mean Abs dP-A

High Level Workflow Graph:

Detailed Workflow Graph:

images/generated/motion_statistics_detailed.png

Examples

>>> from CPAC import generate_motion_statistics
>>> wf = generate_motion_statistics.motion_power_statistics("generate_statistics")
>>> wf.inputs.inputspec.movement_parameters = 'CPAC_outupts/sub01/func/movement_parameteres/rest_mc.1D'  
>>> wf.inputs.inputspec.max_displacement = 'CPAC_outputs/sub01/func/max_dispalcement/max_disp.1D'  
>>> wf.inputs.inputspec.motion_correct = 'CPAC_outputs/sub01/func/motion_correct/rest_mc.nii.gz'  
>>> wf.inputs.inputspec.mask = 'CPAC_outputs/sub01/func/func_mask/rest_mask.nii.gz'  
>>> wf.inputs.inputspec.transformations = 'CPAC_outputs/sub01/func/coordinate_transformation/rest_mc.aff12.1D'  
>>> wf.inputs.inputspec.subject_id = 'sub01'
>>> wf.inputs.inputspec.scan_id = 'rest_1'
>>> wf.base_dir = './working_dir'  
>>> wf.run()  

References

1: 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. doi:10.1016/j.neuroimage.2011.10.018
2: Power, J. D., Barnes, K. A., Snyder, A. Z., Schlaggar, B. L., & Petersen, S. E. (2012). Steps toward optimizing motion artifact removal in functional connectivity MRI; a reply to Carp. NeuroImage. doi:10.1016/j.neuroimage.2012.03.017
3: Jenkinson, M., Bannister, P., Brady, M., Smith, S., 2002. Improved optimization for the robust and accurate linear registration and motion correction of brain images. Neuroimage 17, 825-841.