A high-performance ceramic volume coil for preclinical MRI

A novel volume radio-frequency (RF) coil built around a cylindrical ceramic dielectric (relative permittivity ε_r = 270) was developed for high-field small-animal magnetic resonance imaging (MRI). Finite element simulations were used to optimize the resonator geometry, resulting in an inner diameter of 30 mm, an outer diameter of 47 mm and a length of 43 mm, which is tuned to approximately 400 MHz resonance frequency. The coil is tuned and matched solely by two inductively coupled loops, eliminating the need for lumped-element tuning and matching capacitors. In the loaded state the coil exhibits a quality factor of 105 and very uniform transmit fields, with a B₁ homogeneity of 98.2% in the unloaded condition. Phantom experiments show 97% signal uniformity across 0.7 mm slices and a signal-to-noise ratio (SNR) ranging from 55 to 220 along the coil axis. B₁ mapping confirms accurate excitation (mean actual-to-nominal flip-angle ratio = 1.05) with a coefficient of variation of 1.9%. High-resolution mouse images demonstrate that the ceramic resonator provides excellent anatomical detail, confirming its utility for preclinical MRI. This dielectric-resonator design delivers B₁ homogeneity comparable to or better than conventional coils while simplifying hardware, improving tuning stability and reducing RF losses, establishing it as a cost-effective and robust solution for quantitative high-field preclinical MRI.