A micro planar coil for local high resolution magnetic resonance imaging

This paper reports on a flexible micro planar coil for an MR (Magnetic Resonance) catheter. High resolution images can be obtained by using the MR catheter. Two types of coils of 5 mm and 20 mm in diameter were fabricated. Both of the coils were designed to have inductance of 1.0 muH at 8.5 MHz. The proto-type MR catheters were made by attaching the micro coils to the tip of acrylic pipes. In order to evaluate the MR catheters, the sensitive area and SNR (Signal to Noise Ratio) were measured. SNRs of the MR catheters were about three to eight times higher than that of a standard medical coil. Furthermore, we demonstrated that high resolution MR images can be achieved by using the MR catheters. MR images of a gumbo (Abelmoschus esculentus) were acquired with 0.5 x 0.5 x 1.0 mm³ resolution. While clear MR images were not able to be taken by the standard medical coil due to its low SNR, we were able to observe the gumbo and distinguished its seeds one by one in the MR images taken by the MR catheters.