Hello SPM experts!
I am in desperate need of some help. If you have 3 different
cognitive scores that were
measured from 3 different cognitive tasks, can you then correlate
these scores with each pixel's FA value (DTI output) in the DTI
brain map? Could this be done using only SPM? If so, can someone
explain how?
Thank you!
Jessica, NY
"Voxel-based correlational analysis. For each slice position,
analysis of the DTI data produces mean diffusivity, FA, and T2-
weighted images, which are identical in anatomic position. The
first step in image processing involved stripping of the skull and
dura using an automated algorithm22 (Brain Extraction Tool; Oxford
Centre for Functional Magnetic Resonance Imaging of the
Brain; http://www.fmrib.ox.ac.uk/fsl/bet/index.html). For each
subject,
the T2-weighted images were then fitted to a symmetric
echo-planar MRI brain template using a 12-parameter, affine
normalization
algorithm from Statistical Parametric Mapping23 (SPM
99, Functional Imaging Laboratory, Institute of Neurology,
University
College London, UK; http//www.fil.ion.ucl.ac.uk/spm). A
symmetric echo-planar template was used. An identical transformation
was then applied to the mean diffusivity and FA images.
This was repeated for all subjects so that a full set of DT images
was produced, all fitted to an identical template. All of the
normalized
images were reviewed visually to ensure that there were
no obvious registration errors. The normalized images were then
smoothed using an isotropic Gaussian filter (full width half maximum
4 mm). This process reduces the impact of small errors in
registration by recalculating the intensity at each voxel based on a
weighted mean of intensity at that voxel and surrounding voxels."
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