The calculation of the hemispheric laterality is a method that has increased its use by health professionals and research groups related to the field of functional brain activity. The implementation of this is done through technology guided to design and obtain the Regions of Interest (ROIs) for the subsequent calculation of the Laterality Index. In pursuit of knowing many tools that allows the development of this technique, was tested the free access software ImageJ to calculate the laterality index defining the ROI in the same application. The software tests were performed with functional magnetic resonance images(fRMI) images of NITRC for the frames, with binary images for the functional test performing the end-To-end calculation and, subsequently, to test its performance in the field, 7 fMRI from the ADNI database were used, the study allowed us to determine the quantification of the ROIs, drawing manually and the error that maybe has. All the test results showed a good overview of the software in the research and hospital applications having a small error in the quantification of the ROIs largely caused for human mistakes. Finally, these results allow to validate the correct operation of the application.