Efficiency evaluation of a ¹³C Magnetic Resonance birdcage coil: Theory and comparison of four methods

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• 作者：Giulio Giovannetti^a ; ^b ; ^{giovannetti@ifc.cnr.it} ; Francesca Frijia^b ; Valentina Hartwig^a ; ^b ; Luca Menichetti^a ; ^b ; Jan Henrik Ardenkjaer-Larsen^c ; ^d ; Daniele De Marchi^b ; Vincenzo Positano^b ; Luigi Landini^e ; ^b ; Massimo Lombardi^b ; Maria Filomena Santarelli^a ; ^b
• 关键词：Magnetic Resonance ; Radiofrequency coils ; Coil efficiency
• 刊名：Measurement
• 出版年：2013
• 出版时间：August, 2013
• 年：2013
• 卷：46
• 期：7
• 页码：2201-2205
• 全文大小：633 K

文摘

Radiofrequency coils in Magnetic Resonance systems are used to produce a homogeneous B₁ field for exciting the nuclei and to pick up the signals emitted by the nuclei with high signal-to-noise ratio. Accordingly, coil performance affects strongly the quality of the obtained data and images.

Coil efficiency, defined as the B₁ magnetic field induced at a given point on the square root of supplied power P, is an important parameter that characterizes coil performance, since by maximizing efficiency will also maximize the signal-to-noise ratio.

This work describes and compares four methods for coil efficiency estimation, based on different theoretical approaches. Three methods allow efficiency measurement by using ¡°probe techniques¡± (perturbing loop, perturbing sphere and pick-up coil), which can be used both on the bench and inside the scanner, while an ¡°NMR technique¡± has been employed for comparison purpose.

Methods were tested on a ¹³C birdcage coil tuned at 32.13 MHz.