The research activity of this thesis project has led to the development of a Computer Aided Diagnosis (CAD) system for the analysis of breast cancer lesions using Mammary Magnetic Resonance images. The main objective of this system is the tumor lesions segmentation and their characterization. The process consists of five main parts: image pre-processing, regions of interest contouring, lesions segmentations, heuristic analysis of the results and parametric characterization of the selected regions.A MATLAB algorithm was therefore created for:1. Image pre-processing, images loaded are processed to highlight lesions.2. Breast segmentation, the breasts are identified to prevent false positives (FP) due to structures such as heart and vessels that are not of clinical interest in this application.3.