Читать книгу Magnetic Resonance Microscopy - Группа авторов - Страница 39

The accuracy of this SNR estimation model and its constitutive steps was studied for ring resonators with dimensions fitting microscopic samples, and dielectric materials with permittivity adequate for the range of frequencies of MRM. For example, the normalized power loss term in Equation 2.8 has been evaluated from the field distribution calculated in numerical simulations and with the semi-analytical method for varying electromagnetic properties of a sample for a given probe. As can be seen in Figure 2.8, the relative error between the two approaches never exceeds 5.1%. The SNR values predicted by numerical simulations and those obtained with the semi-analytical method are compared in Figure 2.9. The maximum relative error between the two approaches is 8% in the worst-case scenario.

Figure 2.8 Relative error between the numerical simulations (CST Studio, Eigenmode Solver) and the semi-analytical model on the prediction of the normalized power losses term The error is plotted as a function of the sample conductivity and for three different sample permittivities. The ring resonator has the same properties as in [30]. The relative error is always below 5.1%. Figure reproduced with permission from [21].

Figure 2.9 Comparison of the SNR predictions obtained with numerical simulations and with the developed semi-analytical model (SAM). The maximum relative error between the two approaches is 8%. The ring resonator has the same properties as in [30]. Data reproduced with permission from [21].