An Artificial Shield for MRI Birdcage Coil with Constructive Interference

In this contribution, an artificial shield for an MRI birdcage coil based on a cylindrical miniaturized corrugated structure is proposed. The presence of a conventional metallic shield around the birdcage resonator leads to a destructive interference of the primary magnetic field of the coil and the reflected field inside the coil (in the region of an investigated sample). At the same time, the fields constructively interfere in the region between the coil and the shield. As a result, the efficiency of the coil may be limited. The proposed artificial shield has a miniaturized corrugated structure, which demonstrates the property of a constructive interference inside the coil. It has been shown that the proposed structure placed around the birdcage coil can increase the efficiency at its resonance similarly to an ideal cylindrical magnetic wall of the same diameter.