2009 年 47 巻 6 号 p. 484-493
In this study, we fabricated micro planar coils as a receiver for a high sensitive MRI (Magnetic Resonance Imaging). According to the calculation of the scale effect, the sensitivity of the coil increases with decrease of the diameter of the coil under the condition of fixed inductance. The micro planar coils of 5 and 20 mm in diameter were fabricated by using MEMS technology. The resistance and inductance of the 20 mm coil were 1.4 Ω and 1.15 μH at 8.5 MHz, respectively. Those of the 5 mm coil were 2.0 Ω and 1.05 μH, respectively. The MRI signal receivers were made by attaching the micro coils to the tip of acrylic pipes. The SNRs (Signal to Noise Ratio) of MR images of phantom were measured by the micro planar coils and the medical MRI coil of 200 mm in diameter. The SNRs of MR images taken by the micro planar coils were about 8 times as high as the MR image taken by the medical coil. MR images of an okra (Abelmoschus esculentus) were acquired by fabricated MRI signal receivers with the voxel size of 2.0 × 2.0 × 2.0 mm3 and 0.5 × 0.5 × 1.0 mm3. Since the sensitivity of micro planar coils was high, we were able to clearly observe inner structure of the okra.