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http://dx.doi.org/10.5515/KJKIEES.2012.23.1.096

B1+ Homogenizaion over Whole Field of View in High Field MRI  

Kim, Hong-Joon (Department of Electrical Engineering, IT College, Kyungpook National University)
Son, Hyeok-Woo (School of Electronics Engineering, IT College, Kyungpook National University)
Cho, Young-Ki (School of Electronics Engineering, IT College, Kyungpook National University)
Yoo, Hyoung-Suk (Department of Biomedical Engineering, School of Electrical Engineering, University of Ulsan)
Publication Information
The Journal of Korean Institute of Electromagnetic Engineering and Science / v.23, no.1, 2012 , pp. 96-100 More about this Journal
Abstract
In high static field magnetic resonance imaging(MRI) systems, $B_0$ fields of 7 T and 9.4 T, the impressed RF field shows larger inhomogeneity than in clinical MRI systems with B0 fields of 1.5 T and 3.0 T. In multi-channel RF coils, the magnitude and phase of the input to each coil element can be controlled independently to reduce the non-uniformity of the impressed RF $B_1^+$ field. The convex optimization technique has been used to obtain the optimum excitation parameters with iterative solutions for homogeneity in a selected ROI(Region of Interest). To demonstrate the technique, the multichannel transmission line coil was modeled together with a human head phantom at 400 MHz for the 9.4 T MRI system and $B_1^+$ fields are obtained. In this paper, all the optimized $B_1^+$ in each isolated ROIs are combined to achieve significantly improved homogeneity over the entire field of view. The simulation results for 9.4 T MRI systems are discussed in detail.
Keywords
Magnetic Resonance Imaging(MRI); Convex Optimization; Transmission Line Coil; RF $B_1^+$ Field; Parallel Excitation; High Field MRI;
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