Optimisation of a Magnetic Resonance Imaging RF probe through time reversal with TLM

Abstract

The feasibility of optimising a loaded Magnetic Resonance Imaging RF probe using time reversal analysis and a time domain electromagnetic solver is demonstrated in this paper. It is shown that the geometry of a Magnetic Resonance Imaging RF probe can be refined to improve the field distribution within a sample. In this novel technique the longitudinal electric field is used as the error term for the field within a biological sample and also as the source function for a time reversal simulation. The output of the time reversal simulation will then indicate how the original probe can be adjusted or supplemented to improve the original field distribution. Two examples are given to demonstrate the utility of this approach. The first is the design of a saddle probe and the second is the design of a microstrip RF coil. Although this approach is limited to lossless structures, the results can still provide a valuable insight for structures and biological loads with significant loss. This is a fast and efficient optimisation method which can lead to novel RF structures.