Displaying TSA results

Outputs of the statistical analysis

The TSA statistical analysis can be run using two scripts: tsa_stats (from earlier versions of DTI-TK) or tsa_stats_glm. These two scripts generate vtk outputs with different attributes. In fact, they rely on the meshcluster and the meshglm functions of cmrep, respectively.

1. outputs obtained with tsa_stats. For each of the tracts, there are two outputs: [file_name].med.[type].vtk and [file_name].med.[type].clusters.ttst.[threshold]_pos.[feature].vtk (or [file_name].med.[type].clusters.ttst.[threshold]_neg.[feature].vtk)
2. outputs obtained with group_tsa_stats: Two main outputs will result from the analysis: [file_name].med.[type].vtk and [file_name]_edges.med.[type].clusters.[feature]_[threshold].vtk

where:

• [type] is mean or maxFA (see Sampling values over all the subjects)
• [threshold] is the p-value threshold use in the statistical analysis
• [feature] is the feature analyzed (FA, ADC, for example)

These results can be simply visualized with paraview, as it is the case below:

Difference in FA between men and women in the right corticospinal tract. T-values are displayed showing increased FA values in the inferior part of the CST. The significant region is represented in black (result obtained with meshcluster, left) and outlined in black (results obtained with meshglm, right)

Displaying all the tracts

Another way of displaying the tract is to use these two scripts:

1. picstmap_v2.py
2. tsafig.bash

which are combined here make_sshots.sh

To do so, Imagemagick, vtk and python must be installed on your computer.