The ‘data_gfa’ summarizes anisotropic properties of the Orientation Distribution Function (ODF) of the fibres using the generalized fractional anisotropy (GFA) metric, based on the GQI method.
The file ‘data.nii.gz’ is in gzipped NIfTI format. The R-package oro.nifti is required to read NIfTI files.
The file ‘data_gfa’ was produced by the function
gqi.odfvmf (using the default arguments) included in gdimap.
Functions for visualization of RGB maps and line-maps are included in gdimap.
The output files ‘data_V1.nii.gz’ and ‘data_gfa.nii.gz’ are compatible with the "FSL/fslview" tool for RGB map and line map visualization.
For reasons of limited CRAN storage space, the source data set contains just 4 coronal slices as indicated in
Ferreira da Silva, A. R. Computational Representation of White Matter Fiber Orientations, International Journal of Biomedical Imaging, Vol. 2013, Article ID 232143, Hindawi Publishing Corporation http://dx.doi.org/10.1155/2013/232143.
Ferreira da Silva, A. Facing the challenge of estimating human brain white matter pathways. In Proc. of NCTA 2012 - Int. Conf. on Neural Computation Theory and Applications (Oct. 2012), K. Madani, J. Kacprzyk, and J. Filipe, Eds., SciTePress.
Whitcher, B., Schmid, V. J., and Thornton, A. Working with the DICOM and NIfTI data standards in R. Journal of Statistical Software 44, 6 (2011), 1-28.
Jenkinson, M., Beckmann, C. F., Behrens, T. E., Woolrich, M. W., and Smith, S. M. Fsl. NeuroImage 62, 2 (2012), 782-790.