Magnetic Resonance Imaging (MRI) systems rely on a complex interaction of different physical domains: electromagnetic fields trigger a response of nuclear spins inside the human body, while thermal heating of the body needs to be controlled. The quality of the resulting MR image depends both on the homogeneity of the underlying RF fields and on the sequence chosen to create the image. In this webinar we will present a co-simulation of CST MICROWAVE STUDIO (CST MWS) for the coil design and the Jülich Extensible MRI Simulator (JEMRIS – www.jemris.org) to show these joint effects. CST MWS is used to design and simulate the MRI RF coil. This is a challenging task, especially for modern high field systems. Typically the "coils" are based on multi-channel systems which require circuit based matching and tuning to obtain the desired homogeneous field overlay. The new CST MRI-toolbox helps to directly evaluate the essential quantities such as the B1+ and B1- fields, their statistical properties, but also safety relevant quantities such as general averaged SAR results, "worst case SAR" of multi-channel systems or "total SAR per material". Transient thermal heating based on the bioheat equation can also be monitored.JEMRIS is used to simulate the image generation based on the Bloch equations, with EM fields simulated in MWS and the selected MR sequence as inputs. The images obtained through simulation show potential artefacts due to non-ideal field distributions or the sequence properties. Additional outputs can be generated to obtain important quantities such as g-factors and the image signal to noise ratio.