Modular Metamaterials for Adaptable MRI Signal Control: Combining Dipole Array With a New Hexagon-Based Artificial Dielectrics.

Emerging concepts of metamaterials for MRI offer improved image quality through enhanced RF field control. However, current designs are often limited by bulky configurations, dielectric losses, and limited adaptability. Patient-specific optimization-essential for improving field homogeneity, boosting local SNR, and addressing anatomical variability-requires redesigning each setup. To overcome these limitations, we introduce a hexagonally-packed artificial dielectric, free of any lumped-elements, capable of achieving a wide range of high relative permittivities (εr ≈ 30-1400) suitable for clinical and ultra-high-field MRI. We identify multilayered and in-plane-shifted hexagonal configurations that support compact, modular layouts. Furthermore, we combine these artificial dielectrics with passive-dipole array to create a modular system for adaptable signal enhancement, tuned via electric and magnetic dipole modes by adjusting the length of conductive strips. In vivo 7T MRI results demonstrate enhanced field control and high-resolution imaging. This lightweight, flexible, and modular platform enables patient-specific RF field shaping, thus opening up new avenues for personalized and adaptable MRI technology.