All geometrical characterization results that is visualized in Mist are also saved to files. Summarizing statistics (mean value, standard deviation etc.) and histograms are saved to xml-files, see this video. 3D data are saved to vtk-files. See the reference manual for details about the output from each geometry characterization method.
Loading a saved project loads all input files and results into Mist (File/Save project as and File/Load project). Note that this is the only way of loading previous results into Mist. vtk-files can also be opened in for instance the open-source software Paraview, see this video. For advanced post-processing of the 3D results in Matlab using this code, see the instructions in this video.