Radiofrequency field enhancement with high dielectric constant (HDC) pads in a receive array coil at 3.0T

Abstract

Purpose To investigate the use of a new high-dielectric constant (HDC) material for improving SNR and transmission efficiency for clinical MRI applications at 3T with cervical spine imaging. Materials and Methods Human subjects were imaged using a commercial cervical spine receive array coil on a clinical system with and without pads containing Barium Titanate beads in deuterium water placed around the neck. Numerical electromagnetic field simulations of the same configuration were also performed. Results Experimental and simulated maps of transmit and receive fields showed greater efficiency for imaging the cervical spine when the pads were present. Experimental measurements showed a significant improvement in SNR with the pads present and an average input power reduction of 46%. Conclusion Use of HDC material can enhance SNR and transmission efficiency for clinical imaging of the cervical spine at 3.0 T.

Simple modification of arm position improves B1+ and signal homogeneity in the thoracolumbar spine at 3T

“…RF shimming is sometimes not optimal, as it might be difficult to completely and increase CNR in breast, cervical spine, and abdominal imaging in 3T. [21][22][23] These methods may provide a simple, effective, and low-cost approach for improving image quality. According to Brink et al, a high permittivity pad was more effective than dual-channel RF shimming.…”

A Novel Method to Decrease Electric Field and SAR Using an External High Dielectric Sleeve at 3T Head MRI: Numerical and Experimental Results

“…Compared to previous study, where HDC materials were proposed in the coil-to-sample space, this novel application presents several advantages, including: 1) It does not affect the maximum available sample size, which is limited by the ID of the RF coil, whereas in previous study [2]- [5] the size of the sample was limited by the ID of the HDC material. 2) This design allows more flexibility in optimizing the thickness and the position of the HDC material compared to a coil-to-sample design because usually much more space is available outside the RF coil rather than inside.…”

“…The study showed an improvement in the SNR of about 24%, obtained by manipulating the circulation of electric field within the coil with the HDC material. Other experimental and numerical studies have been performed for high field MRI and MR spectroscopy [8] with several different HDC materials, including distilled water [4], D 2 O [6], calcium titanate (CaTiO 3 ) [10] and barium titanate (BaTiO 3 ) [2], [7]. The electrical permittivity of these materials ranges between 78 [6] and 515 [7], the latter being much higher compared to biological tissues.…”

Improvement of Electromagnetic Field Distributions Using High Dielectric Constant (HDC) Materials for CTL-Spine MRI: Numerical Simulations and Experiments

“…Foo et al have used HDC materials placed within the “coil-to-shield” space [5] to alter EM field. Yang et al used HDC materials placed within the “coil-to-sample” space to decrease energy absorption while increasing SNR during head imaging at high field [6]–[8]. Luo et al used HDC materials to improve SNR and receiver sensitivity at 3.0 T. Calcium titanate (CaTiO 3 ) powder and barium titanate (BaTiO 3 ) beads and powder were used in this study [10].…”