Comparison of Electric and B1+ Fields for Heterogeneous and Homogeneous Anthropomorphic Phantoms and Anatomical Models: Numerical Simulations and Experimental Findings

While numerical phantoms and detailed human tissue models have been available for some time in MR^1-5, the development of experimental phantoms has yet to fully evolve. The growth of rapid prototyping and mimicry of tissues through tissue engineering is making it more possible for realistic electromagnetic phantoms that mimic human anatomy to be available to MR researchers and their collaborators. Wood et al. ⁶ fabricated a realistic head model (shown in Figure 1A) that can be used for a wide-variety of MR purposes and builds on the work of Gradel et al.⁷. However, the argument can still be made as to how beneficial it is to have a heterogeneous anthropomorphic phantom in place of a homogeneous anthropomorphic phantom. We hypothesize that the differences will be greatest in the electric field intensities and distribution as opposed to the B1+ field. In this work, we perform numerical studies and experimental 7T measurements that highlight the differences in the electric field and magnetic field of an anthropomorphic phantom (computer model as well as 3D printed) filled with homogeneous and heterogeneous media in comparison to a 10-tissue segmented head model. The phantom uses a resin plastic material that approximates the electromagnetic constitutive properties of a combination fat, bone and skin.