Numerical simulation of volumetric metamaterial integration for loop RF coil SNR map homogenization in human head MRI

Loop radiofrequency (RF) coils are widely employed for imaging superficial anatomical structures due to their high sensitivity near the coil. However, their performance declines in deeper regions such as the brain, where reduced signal-to-noise ratio (SNR) compromises image quality. In contrast, volumetric coils such as birdcage and array coils are generally preferred for deep tissue, such as brain imaging, because of their ability to provide more uniform SNR distribution across the imaging volume. This study aims to improve the performance of loop coils for human brain applications by designing volumetric metamaterials and integrating them with the loop coils and creating the SNR map of volumetric coils. Geometric optimization of the proposed metamaterials was conducted using full-wave electromagnetic simulations in CST Studio Suite. Results demonstrate that when integrated with metamaterials, loop coils achieve SNR uniformity comparable to dedicated volumetric head coils. Furthermore, the resulting SNR map of metamaterials with loop coils surpasses the performance obtained when metamaterials are used with body or spine coils. Given the complexity and high cost associated with manufacturing brain volume coils, simulation results demonstrate the potential of the proposed metamaterial-integrated loop coils as a practical, cost-effective, and efficient alternative for achieving high-quality brain imaging performance.