Improvements in magnetic field intensity and uniformity for small‐animal MRI through a high‐permittivity material attachment

The ultra‐high field (UHF) small‐animal MRI ( sa ‐MRI) device provides a powerful platform for translational imaging. To achieve a high signal‐to‐noise ratio, as well as sufficient signal homogeneity in abdominal imaging, the RF coil has to be precisely tuned. A novel geometry for a high‐permittivity material (HPM) was designed and integrated into an enlarged (90 mm) birdcage (BC) RF coil. The geometrical design of the HPM attachment was based on a computational calculation, and was compared with the commonly used 72 mm bandpass filter BC coil without any HPM attachments. The resulting RF transmission (| B 1 + |) map clearly shows that the increased coil diameter led to a decreased | B 1 + | intensity. However, this loss in field intensity was mitigated by optimally integrating the HPM attachment with the coil. As a result of this attachment, the proposed design exhibits superior | B 1 + | intensity and uniformity along the main magnetic field z ‐direction.