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The ceramic probe designed in [30] was experimentally compared to the reference probe, which is a solenoid coil optimally designed for the same required field of view.

The measured field patterns in Figure 2.14 confirm that the designed ceramic probe has the same region of homogeneity as the solenoid immersed in Fluorinert™ (the Fluorinert is used to improve both B₁ and B₀ homogeneity of the solenoid [31]), and induces higher transmit field intensity using less input power. Quantitatively speaking, for the same input power, the ceramic probe equivalently provides a field level 2.1 times higher than the solenoid immersed in Fluorinert.

Figure 2.14 Measured transmit field pattern in a homogeneous liquid phantom for the reference optimal solenoid probe with Fluorinert (top) and for the designed ceramic (bottom), at 17.2 T. Data from [30].

The experimental SNR, measured in a tissue-mimicking liquid phantom, was also investigated for both probes in Figure 2.15 (left panel). With the same effective flip angle, the SNR was 2.2 times higher with the ceramic probe than with the solenoid immersed in Fluorinert. This has to be compared to the theoretical prediction: from Figure 2.7, for the designed ceramic probe (indicated as “proposed ceramics”), the semi-analytical method presented in Section 2.3 predicts an SNR gain of 2.5.

Figure 2.15 Experimental comparison of the designed ceramic probe and the reference optimal solenoid at 17 T. (Left) signal and noise maps measured in a homogeneous tissue-mimicking liquid phantom. (Right) microscopy images obtained with both probes; (first line) Ilex aquifolium fruit; (second line) chemically fixed rat spinal cord; (third line) 3D rendering and image slice of a plant petiole (obtained with the ceramic probe). With permission from [30].

Better performance of the ceramic probe can be observed in Figure 2.15 (right panel): microscopy images obtained with this probe demonstrate improved quality compared with those obtained using the reference probe, since more structural details can be distinguished.