A Numerical Postprocessing Procedure for Analyzing Radio Frequency MRI Coils

The design and construction of radio frequency (RF) coils for application-specific magnetic resonance imaging purposes are generally extensive, iterative engineering endeavors that involve multiple electromagnetic simulations followed by tuning and matching on the bench. Computational models of RF coil structures typically take into account the conductor topology; however, they do not address the deployment of lumped circuit elements for tuning, matching, and decoupling. As a result, the design engineer must frequently resort to exhaustive trial-and-error attempts to ensure that the coil, or coil array, is functional at the target resonance frequency. Because coil losses are often not easily predictable in simulations, the final result can be an inferior prototype construction. In this article, a general numerical procedure is outlined that enables the effective simulation and performance comparison of RF coils. The procedure relies on an integrated modeling approach, which combines full-wave electromagnetic simulations with a scattering parameter network representation of all relevant tuning, matching, and decoupling elements. With this combined distributed-lumped simulation approach, detailed comparative studies can be conducted on the basis of a figure of merit parameter that is proportional to the signal-to-noise ratio. Furthermore, major loss mechanisms affecting coil performance can readily be identified and quantified. (C) 2011 Wiley Periodicals, Inc. Concepts Magn Reson Part A 38: 133-147, 2011.