Metamaterials for Clinical Magnetic Resonance Imaging

ABSTRACT Magnetic resonance imaging is an indispensable clinical modality, prized for its excellent soft‐tissue contrast and non‐ionizing nature. In general, its performance is fundamentally determined by the signal‐to‐noise ratio. For years, the improvement of the signal‐to‐noise ratio has historically been addressed through hardware‐centric approaches, such as increasing static magnetic field strength and employing advanced radiofrequency coils. As these solutions approach their physical and economic limits, engineered metamaterials have emerged as a fundamentally new and design‐driven paradigm. By enabling a powerful control over the radiofrequency magnetic field in a magnetic resonance imaging system, these metamaterials‐based devices can substantially enhance the imaging performance without requiring costly hardware modifications. In this review, we provide a unified framework for this burgeoning field, establishing a roadmap from physical principles to clinical translation. We first elucidate the foundational principles governing the manipulation of the radiofrequency magnetic field by metamaterials. We then systematically summarize the key design strategies for application‐specific imaging enhancement, ranging from the engineering of resonant unit cells to the functional arrays. Finally, we chart the expanding applications of these technologies. By identifying outstanding challenges, we provide an outlook on the future trajectory of metamaterials in clinical magnetic resonance imaging.