Abstract
Magnetic Resonance Imaging (MRI) of the wrist is difficult because the wrist has a complicated structure and the limitations of the conventional rigid radiofrequency (RF) coils. This research investigates the design and electromagnetic performance of a 4-channel flexible RF coil array intended to improve high-field (7T) wrist MRI imaging. The primary aim is to evaluate whether a flexible, dielectric-loaded configuration offers superior tuning stability, field uniformity, and safety compared to rigid coil structures. The coil was designed and tested in ANSYS HFSS using a realistic straight and bent wrist model, both with and without dielectric loading. The most important performance metrics were S parameter matching, the distribution of the electric field (E-field) and the magnetic field (H-field), and the Specific Absorption Rate (SAR). Across all configurations, the flexible coil demonstrated more stable impedance matching, with resonance frequencies near the expected 299 MHz i.e., resonance frequency. Field simulations show that the flexible RF coil array produced smoother and more uniform E-field and H-field distributions, while rigid coils exhibited pronounced hotspots caused by coil–tissue distance. SAR analysis showed that the flexible coil reduced high intensity localized absorption and achieved even power deposition. Overall, the results show that flexible RF coils are better than rigid coils because of the conformity, have a higher B₁⁺ field efficiency, and safer, even power deposition compared with rigid coils. These findings indicate strong potential for the flexible 4-channel design to enhance image quality, patient comfort, and safety in next-generation 7T wrist MRI systems.