Читать книгу Magnetic Resonance Microscopy - Группа авторов - Страница 33

Take-home message: It is possible to model the first TE mode of cylindrical dielectric resonators, at the cost of manually writing the mode’s field expression and numerically solving a set of equations.

Conventional MR coils, like the solenoid, have been extensively studied from a theoretical point of view and several design tools are now readily available to optimize their performance. So far, theoretical approaches have been proposed to describe the resonant modes of dielectric resonators, but rarely in the context of their use in MRI. This implies that the noise contributions of the ceramic coil need to be identified and quantified in order to estimate the achievable SNR. Provided that transmit power is enough to reach a desired flip angle (as in the case of MRM), the SNR can be evaluated as for other transceiver probes. In this section, we describe an approximate method to calculate the magnetic and electric fields of the first TE mode (TE_01δ) of a cylindrical resonator sketched in Figure 2.1; however, the methodology used to study this particular mode can be applied to any higher-order or different mode type.

Figure 2.1 TE_01δ mode of a cylindrical resonator: field-line schematic and notations.