FIG. 3.

Summary of the main physical coil dimensions, the geometrical sample matching via the relative filling factor η_R as well as the RF characteristics (Q_U, Q_L, and Q_R) of all the coils considered in this study. The measurement of the Q factor of each coil was assessed systematically several times both unloaded and loaded showing negligible variations (less than 0.5%). No loading effect was noticeable when inserting the sample in any of the resonator but in the smallest coil (3% between unloaded and loaded). The measured sensitivity of each resonator is reported relative to a commercial coil (here a mouse head coil from Doty Scientific, Inc.) used as a reference. Some of the characteristics for the commercial Bruker coils are not reported due to our inability to measure the corresponding parameters under the same conditions due to the electrical circuit setup (*) or to the open nature of the surface structure generating an inhomogeneous RF field (**).