At present, the numerical simulation of the mechanical behavior of human tissues in the field of medicine is a field of study that has aroused great interest in the scientific community. The study of the behavior of these tissues entails a great difficulty, partly attributed to the fact that the behavior of these tissues changes from patient to patient and in many occasions it is not possible to perform direct experiments on the tissue to determine its elastic properties. For this purpose, the present work proposes a method to find these properties assuming a constitutive model of Mooney-Rivlin. This method is based on the information provided by medical images in two situations of organ deformation and, through a process of optimization based on the gradient, the elastic properties of the constitutive model are obtained with precision. The numerical experiments performed demonstrate the validity of the method for the example used.