• Abdeddaim, Redha
• Glybovski, Stanislav
• Enoch, Stefan
• Ciobanu, Luisa
• Voznyuk, Ivan
• Moussu, Marine A. C.

Abstract

Magnetic Resonance Microscopy (MRM) consists in imaging tiny samples by exploiting the MR signal of hydrogen atoms abundantly present in biological materials. The highest resolution attainable is limited, in practice, by the Signal-to-Noise Ratio defined as the ratio of the magnetic field amplitude in the sample over the noise generated by the probe, its feeding circuit and the sample itself. The reference volumetric detector for MRM is the solenoid, a cylindrical coil of copper wire, extensively studied in the work of Minard and Wind ([1], [2]). The SNR achieved with such a probe is intrinsically limited by metal-losses due to the winding, but also by the conservative electric field distribution within the sample that generates dielectric losses responsible for noise [3]. In this work, we study, from a theoretical point of view, an alternative type of probe for MRM, based on high-permittivity, low-loss ceramic resonators [4]. The first Transverse Electric eigenmode of such a dielectric ring resonator is excited to create a strong magnetic field within the sample with a low electric field distribution in this region [5]. By analytically describing analytically the field distribution of this resonant mode as well as the loss contributions of the probe [6], we theoretically demonstrate that such dielectric probes built with recently developed low-loss ceramics allow a SNR enhancement of more than two-fold for most biological samples. This was experimentally confirmed by comparing the SNR of the optimal solenoid coil with the SNR of a ceramic probe in the case of a rat spinal cord sample imaged at 17.2 T

Topics

• impedance spectroscopy
• Hydrogen
• copper
• ceramic
• biological material
• wire
• microscopy