VOI Tool Utility was developed in PET Lab Institute intended to analyze Volumes of Interest (VOIs). This application has set of predefined anatomical VOIs that corresponds to all Talairach Atlas Labels but can save any VOI as SPM compatible image used for masking. Statisticians may also use the saved signal intensity data extracted from a set of VOIs as plain ASCII text file, but saving and extracting signal intensity data as plain ASCII text file are only limited to PET/SPECT models. This software is developed by Microsoft under Windows 98 operating system and only tested with MATLAB 6.0 Release 12. It can be used in any MATLAB supported platform and uses only features incorporated in MATLAB 5.3. VOI Tool utility can be installed by unzipping the file and adding installation folder to MATLAB's search path and should contain one subfolder "AnatomicalVoi", set of .m files and one .mat ihb_VoiDfl.mat file.