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The field dependence of NMR imaging. I. Laboratory assessment of signal‐to‐noise ratio and power deposition
Author(s) -
Chen CN.,
Sank V. J.,
Cohen S. M.,
Hoult D. I.
Publication year - 1986
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.1910030508
Subject(s) - electromagnetic coil , nuclear magnetic resonance , signal (programming language) , signal to noise ratio (imaging) , noise (video) , reciprocity (cultural anthropology) , sensitivity (control systems) , noise power , scanner , radiofrequency coil , field (mathematics) , magnetic field , acoustics , optics , power (physics) , physics , computer science , electronic engineering , mathematics , engineering , artificial intelligence , psychology , social psychology , quantum mechanics , pure mathematics , image (mathematics) , programming language
Abstract A method is proposed for measuring on the bench the NMR signal‐to‐noise ratio of rf probes, (over the range 1–100 MHz) and also the power deposited in patients during the imaging experiment. The technique is based on the principle of reciprocity, in that a direct relationship exists between the magnetic field generated (upon transmission) by a matched probe coil and the signal‐to‐noise ration delivered by the same coil when used as a receiver. The construction and use of a calibrated sense coil for measuring the field is described, and the precautions and theory necessary for accurate measurement and understanding are outlined. Finally, the method is verified by comparison with a direct spectral measure of sensitivity obtained from a small doped water sample placed in NMR imaging equipment. © 1986 Academic Press, Inc.