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Radiofrequency Field Calculations for High Field MRI

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Ultra High Field Magnetic Resonance Imaging

Part of the book series: Biological Magnetic Resonance ((BIMR,volume 26))

Abstract

In MRI, increasing radiofrequency magnetic (B 1) field frequency is a consequence of employing higher static magnetic (B 0) field strengths in the drive to improve signal-to-noise ratio (SNR). Due to the direct proportionality between B 0 field strength and B 1 field frequency in MRI, B 1 field distributions become more complex at higher B 0 fields due in part to shorter wavelengths and penetration depths. Consequently, it becomes both more difficult to calculate RF field behavior and more important to do so accurately for high-field MRI. In this chapter the basics of electromagnetic properties of tissue, the method of radiofrequency field calculation currently most prevalent in high-field MRI (the FDTD method), and methods for relating calculation results to MRI are covered briefly before results from calculations are used to discuss current challenges in high-field MRI including central brightening, SNR, power absorption by tissue, and image homogeneity.

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  1. Department of Radiology, Pennsylvania State University, NMR/MRI Building, H066 500 University Drive, Hershey, PA, 17033, USA

    Christopher M. Collins

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Collins, C.M. (2006). Radiofrequency Field Calculations for High Field MRI. In: Ultra High Field Magnetic Resonance Imaging. Biological Magnetic Resonance, vol 26. Springer, Boston, MA. https://doi.org/10.1007/978-0-387-49648-1_8

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