The Shepp-Logan phantom was created as a standard for computerized tomography (CT) image reconstruction simulations of the head. The phantom is also used frequently for magnetic resonance image (MRI) reconstruction and k̃space simulations. However, while the CT version incorporated the radiation attenuation properties of the head and brain, the MRI version of the phantom was neither adapted to MR physics nor defined as a viable standard. As a result, it is not currently possible to compare and validate MR simulations from different research studies. In this paper, we present 2D and 3D Shepp-Logan MRI phantom standards and their analytic k̃space representations based on existing CT standards after modification for MR physics. The standard includes T1 and T2 relaxation times for different fields strengths based on current literature.