Offset-tuned Bilateral-side Inductively Coupled RF Coils for Preclinical MRI at 15.2 T

Abstract

A small coverage of magnetic flux density (B₁) and its inhomogeneity are intrinsic problems of conventional surface coils. Therefore, offset-tuned bilateral-side inductively coupled radiofrequency (RF) coils have been specifically designed to overcome these problems. Herein, we proposed bilateral-sided wireless coils for improving the B1-field uniformity by simultaneously adding a supplemental secondary coil (s-coil) to the primary coil (pcoil) in the orthogonal direction. The offset-tuned frequency of the s-coil was evaluated and compared from 0 to +60 MHz with a +10 MHz interval at the Larmor frequency of the p-coil. Using mathematical EM modeling, we optimized the +60-MHz offset-tuned s-coil at 15.2 T. Thus, a combined coil configuration with p-coil of 655 MHz and two s-coils of 710 MHz was obtained. This combined coil configuration can overcome the B₁-field inhomogeneity of p-coils in 15.2 T small animal magnetic resonance scanner and can be extended to overcome the volume coil array inhomogeneity.