A novel method for coil efficiency estimation: Validation with a 13C birdcage

Giulio Giovannetti, Francesca Frijia, Valentina Hartwig, Luca Menichetti, Daniele De Marchi, Vincenzo Positano, Luigi Landini, Massimo Lombardi, Maria Filomena Santarelli, Jan Henrik Ardenkjær-Larsen

Research output: Contribution to journalJournal articleResearchpeer-review


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 both the transmit and receive performance of the radiofrequency (RF) coil. Maximizing coil efficiency will maximize also the signal-to-noise ratio. In this work, we propose a novel method for RF coil efficiency estimation based on the use of a perturbing loop. The proposed method consists of loading the coil with a known resistor by inductive coupling and measuring the quality factor with and without the load. We tested the method by measuring the efficiency of a 13C birdcage coil tuned at 32.13 MHz and verified its accuracy by comparing the results with the nuclear magnetic resonance nutation experiment. The method allows coil performance characterization in a short time and with great accuracy, and it can be used both on the bench and inside the scanner. (c) 2012 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 41B: 139143, 2012
Original languageEnglish
JournalConcepts in Magnetic Resonance. Part B: Magnetic Resonance Engineering (Online)
Issue number4
Pages (from-to)139-143
Publication statusPublished - 2012


  • B1 calibration
  • radiofrequency coils
  • coil efficiency
  • dual-loop probe

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