Numerical Study of the SNR and SAR of MRI Coil Arrays

Coil arrays have become a very popular coil configuration for magnetic resonance imaging. This due to that, an image of a larger area can be obtained with uniform sensitivity and higher SNR as compared to standard MR volume coil. Ultra-fast procedures like parallel imaging and phased-array can take advantage of these properties. It is very important to understand the performance of this type of devices to take full advantage of these imaging schemes. Although, the study of the single and coil arrays pose a great challenge because of the mathematical theory involved, a simulation approach can be adopted to study various coil array configuration. The principal objective of this paper is to propose a simple method to study the performance of coil array. This method numerically simulates the electric field, magnetic field, signal-to-noise ratio and specific absorption rate of MRI coil arrays. A strip of squared-shaped coil array is proposed with three different configurations. To numerically compute the electric and magnetic fields, a commercial software tool based on the Finite-Element Method was used to solve the Maxwell´s equations. Matrices were formed with the image entries of the electric and magnetic fields, and used to compute the signal-to-noise ratio and specific absorption rate of the coil array configurations. Results showed a good agreement with those reported in the literature. The visualization of the electromagnetic fields allows us to study the behavior of a particular coil array configuration. This also facilitates the search for an optimal configuration as a function of the application.