A systematic procedure for the design of printed filters aimed at decoupling Magnetic Resonance Imaging (MRI) loops is presented. The filter (distributed magnetic trap) consists of spiral resonators, it is passive and conformal to the geometry of the antennas to be decoupled. The proposed design method begins from the estimation of the analytical mutual coupling between the MRI loops under the magneto-static approximation. From such analysis, a criterion for optimizing the distributed magnetic trap in terms of number of spiral resonators is proposed and applied at higher frequency. A Dual Tuned coil is employed as test case.