In this thesis the problem of optimization of a permanent magnetic structure for low-field imaging applications is addressed, with particular attention to the homogeneity of the 𝐵𝑧 field within a spherical region of interest defined as FOV (Field of View). The whole work is based on the use of a numerical code in MATLAB environment, based on a Coulomb model for magnetic field calculation. In the initial phase, the code was subjected to an accurate validation by comparison with established software for magnetostatic analysis commonly used in academic and industrial environments. The good agreement between the results confirmed the reliability of the numerical approach adopted.