CAT (computational anatomy toolbox) is a free and open source software package used for the analysis of structural brain imaging data, in particular magnetic resonance imaging (MRI).

[1] Developed by Christian Gaser and Robert Dahnke of the Structural Brain Mapping Group at the University of Jena, CAT is an extension of the SPM software.

CAT provides tools for voxel-based morphometry (VBM),[2] cortical thickness,[3] folding,[4] and gyrification[5] analysis, as well as volume or surface estimates within predefined brain regions of interest.