Investigations on micro-displacement based techniques for resonance frequency control of miniature monolithic resonators dedicated to Magnetic Resonance Imaging

The use of miniature monolithic Multi-turn Transmission Line resonator (MTLR) in Magnetic Resonance Imaging (MRI) allows achieving very high spatial resolution images but calls to dedicated techniques to finely control the resonance frequency of the resonator. This paper presents preliminary investigations on micro-displacement based frequency control techniques dedicated to MTLR. In particular, a tuning technique, based on a dielectric coupling, to tune the coil to the Larmor frequency of the observed protons and a decoupling technique based on short-circuit of the coil winding are studied. Results obtained with both experimental measurements and numerical simulations are presented and micro-devices that could perform automatic and precise frequency shift are proposed.