Article on EM simulation model for a 7 T 8ch transmit coil

Purpose

The purpose of this study is to create an EM simulation model for the NOVA 8Tx/32Rx RF head coil to further develop its applications in research and clinical use. The developed EM model has been made publicly available.

Methods

The coil was modeled as a combination of microstrips in Ansys HFSS. The currents on these microstrips were optimized to match the manufacturer-provided complex magnetic fields inside the coil. The accuracy with which this match can predict the  magnitudes for a phantom with different permittivity and shape was verified using experimental data from a 7 T scanner.

Results

Accurate predictions of both and SAR were obtained using the proposed simulation model, where the structural similarity index for the manufacturer-provided data was greater than 98% for different RF shim patterns. The experimental validation of the model yielded a  structural similarity of over 90% and the average RMS error for random RF excitation scenarios was found as 0.3 µT/.

Conclusion

In this study, we designed an EM simulation model of the NOVA RF transmit head coil. We confirmed the reliability of the model by comparing its predictions with experimental data and validated that the model can estimate distributions in different phantoms for a variety of excitation patterns.

Related data is available in our github page: https://github.com/UMRAM-Bilkent/EM-Simulation-Model-of-A-Clinically-Used-RF-Head-Coil-at-7-T

Full text is available at the Wiley web page https://doi.org/10.1002/mrm.70244