Design of a Halbach Magnet Gradient Coil for High-Resolution Portable MRI

Creating an effective gradient coil is essential for enabling portable, high-quality magnetic resonance imaging (MRI). This study introduces a method that incorporates a power consumption optimization function into spherical harmonic analysis to design an efficient gradient coil for a portable Halbach magnet with a low height-to-diameter ratio. The new design approach resulted in significant improvements over traditional methods, with the Y-direction gradient coil achieving an efficiency of 38.1 mT/m/A, reducing inductance and resistance by 43.09% and 24.77%, respectively. The Z-direction gradient coil also showed enhanced efficiency at 18.1 mT/m/A, a 45.97% improvement. Using this gradient coil design, a portable MRI device was constructed by integrating it with a homemade portable Halbach magnet, radio frequency probe, and electronic components from the laboratory. Imaging tests on a water phantom demonstrated the device’s ability to resolve small structures below 1 mm, achieving an image resolution of $62.5\times 62.5~\mu $ m. Overall, the gradient coil design method presented in this study successfully meets the requirements for portable, high-resolution MRI on-site.