1. A method of aligning a Positron Emission Tomography (PET) Field of View (FoV) with a Magnetic Resonance Imaging (MR) FoV, the method comprising: providing a phantom, wherein the phantom comprises at least one rod containing line sources; imaging the phantom with MR to provide an MR image; imaging the phantom with PET to provide a PET image; applying voids detected in the MR image to align the PET FoV with the MR FoV, wherein the voids originate from the at least one rod when imaging the phantom with MR and the at least one rod provides a PET image using the line sources when imaging the phantom with PET.