Active split-ring metamaterial slabs for magnetic resonance imaging

TL;DR

This paper introduces active split-ring metamaterial slabs with switchable permeability designed to enhance magnetic resonance imaging by improving local signal-to-noise ratio through dynamic magnetic field confinement.

Contribution

It presents a novel design of active split-ring metamaterial slabs with switchable permeability for MRI applications, combining fabrication and experimental validation.

Findings

Slabs can switch permeability automatically using diodes.

Enhanced local signal-to-noise ratio demonstrated.

Effective magnetic field confinement in MRI context.

Abstract

In this work, it is analyzed the ability of split-ring metamaterial slabs with zero/high permeability to reject/confine the radiofrequency magnetic field in magnetic resonance imaging systems. Using an homogenization procedure, split-ring slabs have been designed and fabricated to work in a 1.5T system. Active elements consisting of pairs of crossed diodes are inserted in the split-rings. With these elements, the permeability of the slabs can be automatically switched between a unity value when interacting with the strong excitation field of the transmitting body coil, and zero or high values when interacting with the weak field produced by protons in tissue. Experiments are shown for different configurations where these slabs can help to locally increase the signal-to-noise-ratio.