Pectus excavatum is often corrected by the Nuss procedure, in which a metal bar (usually made of stainless steel) is inserted horizontally into the chest cavity. MRI examination is important to assess the cardiac function with a focus on the right heart. The metal bar causes susceptibility artifacts in cine MRI. We explore the feasibility to improve the B0 field homogeneity using a field correction device to be placed on the surface of the chest utilizing permanent magnets. A device was constructed based on computer simulations. The device generates magnetic multipole fields and effectively improved B0 homogeneity in a phantom.