A Perspective into Ultra High Field MRI RF Coils

Abstract

The advancement of MRI as a radiological instrument has been associated with a constant drive toward higher magnetic field strengths, resulting in higher operational frequencies. More powerful magnets bring the promise of enhanced signal to noise ratio resulting in exquisite resolution, and reduced scan times. At the same time, however, operating MRI at higher frequencies adds significant physical and engineering complexities to the MRI experiment, most notably in designing safe, versatile, and high-performance radiofrequency (RF) coils. This chapter provides RF coil studies that span frequencies ranging form 1.5 to approx. 12 T. The results and conclusions are based on experimental findings using 8 and 1.5T whole-body MRI systems, computational electromagnetics using the finite-difference time-domain method, and analytical derivations using electromagnetic theory. The outcome of these studies is then utilized to provide new avenues and techniques to improve the performance of RF head coils for human MRI at very high fields.