Abstract #1212

Subwavelength dielectric waveguide for human head travelling-wave MRI at 7T

Yang Gao^1,2,3, Tong Liu¹, Tao Hong^1,2, Wen Jiang^1,2, and Xiaotong Zhang^3,4,5,6

¹Hangzhou Institute of Technology, Xidian University, Hangzhou, China, ²National Key Laboratory of Antennas and Microwave Technology, School of Electronic Engineering, Xidian University, Xian, China, ³College of Electrical Engineering, Zhejiang University, Hangzhou, China, ⁴Second Affiliated Hospital of Zhejiang University School of Medicine, Zhejiang University, Hangzhou, China, ⁵MOE Frontier Science Center for Brain Science and Brain-machine Integration, Zhejiang University, Hangzhou, China, ⁶Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Zhejiang University, Hangzhou, China

Synopsis

Keywords: Non-Array RF Coils, Antennas & Waveguides, Non-Array RF Coils, Antennas & Waveguides

Motivation: Radiative excitation (e.g., travelling-wave, TW) has strength in large coverage and low SAR. It’s well compatibility with single-channel (clinical-mode) makes it promising as whole-body excitation solution at UHF. But it has apparent weakness in efficiency.

Goal(s): Improve excitation efficiency as well as homogeneity of TW MRI under clinical-mode.

Approach: Subwavelength dielectric waveguide was designed to enhance excitation efficiency as well as homogeneity through mode conversion, power-focusing, wave-impedance-matching and phase-velocity-matching.

Results: The excitation efficiency was improved by 114% over brain compared to classic TW . SAR efficiency was 10.8% higher than birdcage. The B₁⁺ RMSE in brain was reduced by 21.9% compared to birdcage.

Impact: Our results offered insights into the design of new generation TW MRI excitation systems at UHF. The improved TW MRI systems operated under single channel may hold promises to whole-body imaging at UHF in clinical scenarios.

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