A hybrid gradient coil design method generating ultra-high gradient magnetic field for micro-MRI utilization

Ultra-high gradient strength is crucial for achieving high spatial resolution in advanced magnetic resonance imaging (MRI) applications. However, it is challenging to design gradient coils to generate ultra-high gradient strengths with superior coil operational efficiency in a limited space. In this work, we propose an innovative hybrid gradient coil design approach that synergistically integrates the discrete wire scheme with the current density technique. The primary coils are configured using a discrete wire technique that achieves a compact and high-density winding structure, generating exceptional gradient field intensity. Concurrently, the shielding layer utilizes the current density method and stream function to effectively constrain stray magnetic fields and eddy current effects. Comparative analysis with conventional gradient coils demonstrates that the hybrid design approach achieves a doubling of gradient strength (e.g., 2450 vs 1000 mT/m) and a quadrupling of efficiency (e.g., 49 vs 12 mT/m/A). Furthermore, the mechanical design is also analyzed to ensure structural integrity and manufacturability. This novel design method provides new insights into overcoming the trade-offs among gradient performance metrics, establishing a promising approach for developing new-generation high-resolution MRI systems.