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Comparison and Optimization of Parallel-Transmission RF Coil Elements for 3.0 T Body MRI  

Oh, Chang-Hyun (Dept. of Electronics and Information Engineering, Korea University)
Lee, Heung-K. (Dept. of Electrical Engineering, KAIST)
Ryu, Yeun-Chul (Dept. of Electronics and Information Engineering, Korea University)
Hyun, Jung-Ho (Dept. of Biomedical Engineering, Korea University)
Choi, Hyuk-Jin (Dept. of Electronics and Information Engineering, Korea University)
Publication Information
Journal of the Institute of Electronics Engineers of Korea SC / v.44, no.4, 2007 , pp. 55-60 More about this Journal
Abstract
In high field (> 3 T) MR imaging, the magnetic field inhomogeneity in the target object increases due to the nonuniform electro-magnetic characteristics of the relatively high RF frequency. Especially in the body imaging, the effect causes more serious problems resulting in locally high SAR(Specific Absorption Ratio). In this paper, we propose an optimized parallel-transmission RF coil and show the utility of the coil by FDTD simulations to overcome the unwanted effects. Three types of TX coil elements are tested to maximize the efficiency and their driving patterns(amplitude and phase) optimized to have adequate field homogeneity, proper SAR level, and sufficient field strength. For the proposed coil element of $25cm{\times}8cm$ loop structure with 12 channels for a 3.0 T body coil, the field non-uniformity of more than 70% without optimization was reduced to about 26 % after the optimization of driving patterns. The experimental as well as simulation results show that the proposed parallel driving scheme is clinically useful for (ultra) high field MRI.
Keywords
Transmission RF Coil; Parallel Transmission; SAR; Ultra High Field MRI;
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